Electric Charge & Properties |1 MARKS QUESTION | physics

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Electric Charge & Properties

 

1. What is electric charge?

Answer: Electric charge is a basic property of matter responsible for electric forces.

Explanation: It causes attraction or repulsion between objects.

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2. What are the two types of electric charges?

Answer: Positive charge and Negative charge.

Explanation: Like charges repel and unlike charges attract.

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3. What is the SI unit of electric charge?

Answer: Coulomb (C).

Explanation: It is the standard unit used to measure charge.

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4. What is the charge of an electron?

Answer:

$-1.6 \times 10^{-19} \, C$

Explanation: Electron carries negative charge.

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5. What is the charge of a proton?

Answer:

$+1.6 \times 10^{-19} \, C$

Explanation: Proton carries equal but opposite charge to electron.

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6. What is meant by conservation of charge?

Answer: Charge cannot be created or destroyed.

Explanation: It only transfers from one body to another.

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7. What is quantization of charge?

Answer: Charge exists in discrete amounts.

Explanation: It is always a multiple of elementary charge.

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8. What is the formula for charge quantization?

Answer:

$q = ne$

Explanation: Where 

$n$$e$

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9. What is electrostatic force?

Answer: Force between two charged bodies.

Explanation: It can be attractive or repulsive.

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10. State Coulomb’s Law.

Answer: Force is directly proportional to product of charges and inversely proportional to square of distance.

Explanation: It explains interaction between charges.

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11. Write the formula of Coulomb’s Law.

Answer:

$F = k \frac{q_1 q_2}{r^2}$

$q_1$

$q_2$

$r$

$F = k\frac{q_1 q_2}{r^2} \approx -5.06$

Explanation:

$k$$r$

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12. What is a conductor?

Answer: A material that allows flow of charge.

Explanation: Example: Metals like copper.

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13. What is an insulator?

Answer: A material that does not allow charge flow.

Explanation: Example: Rubber, glass.

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14. What is charging by friction?

Answer: Transfer of charge by rubbing two objects.

Explanation: Electrons move from one body to another.

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15. What is charging by conduction?

Answer: Charging by direct contact.

Explanation: Charge flows from one body to another.

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16. What is charging by induction?

Answer: Charging without direct contact.

Explanation: Redistribution of charges occurs.

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17. What is earthing?

Answer: Transfer of excess charge to the Earth.

Explanation: It neutralizes charged objects.

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18. What is electric field?

Answer: Region around a charge where it exerts force.

Explanation: Other charges experience force in this region.

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19. What is electric field intensity?

Answer: Force per unit charge.

Explanation:

$$E = \frac{F}{q}$$

E=qF​

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20. What happens when like charges are brought close?

Answer: They repel each other.

Explanation: Due to electrostatic repulsion.

21. What is the value of elementary charge (e)?

Answer:

$1.6 \times 10^{-19} \, C$

Explanation: It is the smallest unit of charge carried by electron/proton.

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22. What is the nature of charge on an electron?

Answer: Negative

Explanation: Electrons always carry negative charge.

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23. What happens when opposite charges are brought together?

Answer: They attract each other.

Explanation: Due to electrostatic attraction.

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24. Define electrostatic force qualitatively.

Answer: Force between stationary charges.

Explanation: It acts without physical contact.

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25. What is the dimension of electric charge?

Answer:

$[IT]$

Explanation: Charge = current × time.

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26. What is meant by neutral body?

Answer: A body with equal positive and negative charges.

Explanation: Net charge becomes zero.

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27. Can a body have fractional charge?

Answer: No

Explanation: Charge is always in integral multiples of 

$e$

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28. What is the role of distance in Coulomb’s law?

Answer: Force decreases with square of distance.

Explanation:

$F \propto \frac{1}{r^2}$

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29. What happens to force if distance doubles?

Answer: It becomes one-fourth.

Explanation: Inverse square relationship.

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30. What is electrostatic induction?

Answer: Charge separation without contact.

Explanation: Caused by nearby charged body.

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31. What is a test charge?

Answer: A small positive charge used to detect electric field.

Explanation: It should not disturb the field.

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32. What is electric field direction?

Answer: Direction of force on a positive test charge.

Explanation: Field lines show this direction.

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33. What is the SI unit of electric field?

Answer: N/C

Explanation: Newton per Coulomb.

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34. What is permittivity of free space?

Answer:

$\varepsilon_0$

Explanation: It is a constant used in Coulomb’s law.

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35. What is the value of Coulomb constant (k)?

Answer:

$9 \times 10^9 \, Nm^2/C^2$

Explanation: It depends on medium.

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36. What type of force is electrostatic force?

Answer: Non-contact force

Explanation: Acts without touching.

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37. What is the effect of medium on force?

Answer: Force decreases in a medium.

Explanation: Depends on permittivity.

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38. What are field lines?

Answer: Imaginary lines representing electric field.

Explanation: Show direction and strength.

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39. Do electric field lines intersect?

Answer: No

Explanation: Two directions at one point are not possible.

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40. What is electrostatic shielding?

Answer: Protection from external electric field.

Explanation: Achieved using conductors.

41. What is electrostatic potential?

Answer: Work done per unit charge.
Explanation: It measures energy required to bring a charge.

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42. What is the SI unit of electric potential?

Answer: Volt (V)
Explanation: 1 Volt = 1 Joule/Coulomb.

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43. What is potential difference?

Answer: Difference in potential between two points.
Explanation: It causes flow of charge.

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44. What is equipotential surface?

Answer: Surface with same potential at all points.
Explanation: No work is done moving charge on it.

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45. What is the work done in moving charge on equipotential surface?

Answer: Zero
Explanation: Because potential difference is zero.

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46. What is electric dipole?

Answer: Pair of equal and opposite charges separated by distance.
Explanation: Example: two charges +q and –q.

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47. What is dipole moment?

Answer: Product of charge and separation distance.
Explanation: It is a vector quantity.

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48. Write formula of dipole moment.

Answer:
$p = q \times d$
Explanation: $q$ = charge, $d$ = separation.

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49. What is direction of dipole moment?

Answer: From negative to positive charge.
Explanation: Opposite to electric field direction.

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50. What is torque on a dipole?

Answer: Turning effect in electric field.
Explanation: It aligns dipole along field.

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51. What is the formula of torque on dipole?

Answer:
$\tau = pE \sin\theta$
Explanation: Depends on angle with field.

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52. When is torque maximum on dipole?

Answer: At $90^\circ$
Explanation: Because $\sin 90^\circ = 1$

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53. When is torque zero on dipole?

Answer: At $0^\circ$ or $180^\circ$
Explanation: Dipole is aligned with field.

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54. What is electric flux?

Answer: Measure of electric field passing through a surface.
Explanation: Depends on field and area.

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55. What is SI unit of electric flux?

Answer: Nm²/C
Explanation: Derived from electric field.

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56. State Gauss’s Law.

Answer: Total flux equals charge enclosed divided by permittivity.
Explanation: Fundamental law of electrostatics.

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57. Write formula of Gauss’s Law.

Answer:
$\Phi = \frac{Q}{\varepsilon_0}$
Explanation: $Q$ = enclosed charge.

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58. What is Gaussian surface?

Answer: Imaginary closed surface.
Explanation: Used to apply Gauss’s law.

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59. What happens to electric field inside conductor?

Answer: It is zero.
Explanation: Charges redistribute to cancel field.

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60. Where does excess charge reside in conductor?

Answer: On the surface.
Explanation: Due to repulsion between charges.

61. What is electric field due to a point charge?

Answer: Field around a charged particle.
Explanation: It decreases with distance.

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62. Write formula for electric field due to point charge.

Answer:

$E = k \frac{q}{r^2}$

$q_1$

$q_2$

$r$

$F = k\frac{q_1 q_2}{r^2} \approx -5.06$

Explanation: $q$ = charge, $r$ = distance.

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63. What is direction of electric field for positive charge?

Answer: Away from the charge.
Explanation: Field lines radiate outward.

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64. What is direction of electric field for negative charge?

Answer: Towards the charge.
Explanation: Field lines point inward.

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65. What is superposition principle?

Answer: Net field is sum of individual fields.
Explanation: Fields add vectorially.

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66. What is electric potential due to point charge?

Answer: Potential at a distance from charge.
Explanation: Depends on distance.

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67. Write formula for electric potential.

Answer:
$V = k \frac{q}{r}$
Explanation: Inversely proportional to distance.

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68. What is relation between electric field and potential?

Answer: Field is negative gradient of potential.
Explanation: $E = -\frac{dV}{dr}$

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69. What is potential at infinity?

Answer: Zero
Explanation: Reference point is taken at infinity.

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70. What is electric potential energy?

Answer: Energy stored due to position of charge.
Explanation: Work done in assembling charges.

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71. Write formula for potential energy of two charges.

Answer:
$U = k \frac{q_1 q_2}{r}$
Explanation: Depends on distance and charges.

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72. What is capacitance?

Answer: Ability to store charge.
Explanation: Depends on conductor size and medium.

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73. Write formula for capacitance.

Answer:
$C = \frac{Q}{V}$
Explanation: Ratio of charge to potential.

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74. What is SI unit of capacitance?

Answer: Farad (F)
Explanation: Named after Faraday.

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75. What is a capacitor?

Answer: Device to store charge.
Explanation: Consists of two conductors.

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76. What is dielectric?

Answer: Insulating material placed between plates.
Explanation: Increases capacitance.

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77. What happens to capacitance with dielectric?

Answer: It increases.
Explanation: Due to reduced electric field.

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78. What is energy stored in capacitor?

Answer: Electrical energy stored.
Explanation: Depends on charge and voltage.

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79. Write formula for energy stored.

Answer:
$U = \frac{1}{2}CV^2$
Explanation: Standard energy formula.

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80. What is breakdown of dielectric?

Answer: Loss of insulating property.
Explanation: Occurs at high voltage.

81. What is capacitance of parallel plate capacitor?

Answer:
$C = \frac{\varepsilon_0 A}{d}$
Explanation: Depends on plate area $A$ and separation $d$.

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82. What happens to capacitance if plate area increases?

Answer: It increases.
Explanation: $C \propto A$

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83. What happens to capacitance if distance increases?

Answer: It decreases.
Explanation: $C \propto \frac{1}{d}$

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84. What is dielectric constant?

Answer: Ratio of permittivity of medium to free space.
Explanation: $K = \frac{\varepsilon}{\varepsilon_0}$

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85. What is effect of dielectric constant on capacitance?

Answer: Capacitance increases.
Explanation: $C = K C_0$

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86. What is electric polarization?

Answer: Alignment of dipoles in dielectric.
Explanation: Occurs under electric field.

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87. What is surface charge density?

Answer: Charge per unit area.
Explanation:

$$\sigma = \frac{Q}{A}$$

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88. What is volume charge density?

Answer: Charge per unit volume.
Explanation:

$$\rho = \frac{Q}{V}$$

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89. What is linear charge density?

Answer: Charge per unit length.
Explanation:

$$\lambda = \frac{Q}{L}$$

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90. What is electric field inside hollow conductor?

Answer: Zero
Explanation: Due to shielding effect.

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91. What is potential inside hollow conductor?

Answer: Constant
Explanation: Same at all points inside.

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92. What is relation between force and electric field?

Answer:
$F = qE$
Explanation: Force depends on charge and field.

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93. What is potential gradient?

Answer: Rate of change of potential.
Explanation: It gives electric field.

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94. What is unit of dipole moment?

Answer: Coulomb-meter (C·m)
Explanation: Product of charge and distance.

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95. What is direction of electric field lines between plates?

Answer: From positive to negative plate.
Explanation: Uniform field is formed.

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96. What is uniform electric field?

Answer: Field with constant magnitude and direction.
Explanation: Example: between parallel plates.

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97. What is non-uniform electric field?

Answer: Field that varies with position.
Explanation: Example: near point charge.

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98. What is electric field at center of dipole?

Answer: Zero
Explanation: Fields cancel each other.

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99. What is SI unit of permittivity?

Answer: F/m
Explanation: Farad per meter.

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100. What is electrostatics?

Answer: Study of charges at rest.
Explanation: Deals with static electric forces.

101. What is Coulomb force in vector form?

Answer:

$\vec{F}=k\frac{q_1{q}_2}{r^2}\widehat{r}$

$q_1$

$q_2$

$r$

$F=k\frac{q_1{q}_2}{r^2}\approx -5.06$

Charge and distance sliders update Coulomb force magnitude and direction.

Explanation: Direction is along the line joining charges.

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102. What is unit vector $\widehat{r}$?

Answer: A vector of magnitude 1.
Explanation: It gives direction only.

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103. What is superposition principle for force?

Answer: Net force is vector sum of all forces.
Explanation: Applies to multiple charges.

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104. What is electric field at a point due to many charges?

Answer: Vector sum of fields due to each charge.
Explanation: Based on superposition.

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105. What is relation between electric field and force?

Answer:
$E=\frac{F}{q}$
Explanation: Field is force per unit charge.

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106. What is electric potential due to multiple charges?

Answer: Algebraic sum of potentials.
Explanation: Scalar addition.

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107. What is zero potential point?

Answer: Point where net potential is zero.
Explanation: Due to cancellation.

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108. What is electric dipole axis?

Answer: Line joining two charges.
Explanation: Dipole lies along this axis.

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109. What is equatorial line of dipole?

Answer: Perpendicular bisector of dipole.
Explanation: Passes through midpoint.

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110. What is electric field on axial line of dipole?

Answer: Stronger than equatorial line.
Explanation: Depends on position.

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111. What is electric field on equatorial line?

Answer: Weaker than axial line.
Explanation: Opposite contributions reduce field.

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112. What is nature of field lines near dipole?

Answer: Curved lines.
Explanation: Show combined effect of charges.

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113. What is potential due to dipole at far point?

Answer: Decreases with distance.
Explanation: $V\propto \frac{1}{r^2}$

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114. What is torque direction on dipole?

Answer: Perpendicular to plane of dipole and field.
Explanation: Given by right-hand rule.

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115. What is stable equilibrium of dipole?

Answer: When aligned with field.
Explanation: Minimum potential energy.

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116. What is unstable equilibrium of dipole?

Answer: Opposite to field direction.
Explanation: Maximum potential energy.

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117. What is electric field intensity inside dielectric?

Answer: Reduced
Explanation: Due to polarization.

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118. What is relative permittivity?

Answer: Ratio $\epsilon \mathrm{/}{\epsilon }_0$
Explanation: Also called dielectric constant.

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119. What is effect of dielectric on electric field?

Answer: It decreases electric field.
Explanation: Due to induced charges.

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120. What is capacitance of isolated conductor?

Answer: Ability to store charge.
Explanation: Depends on size and shape.

121. What is electric field due to an infinite line charge?

Answer:
$E=\frac{\lambda }{2\pi {\epsilon }_{0}r}$
Explanation: Depends on linear charge density $\lambda$.

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122. What is electric field due to an infinite plane sheet?

Answer:
$E=\frac{\sigma }{2{\epsilon }_0}$
Explanation: Independent of distance.

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123. What is electric field between two oppositely charged plates?

Answer:
$E=\frac{\sigma }{{\epsilon }_0}$
Explanation: Uniform field is produced.

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124. What is surface charge density symbol?

Answer: $\sigma$
Explanation: Represents charge per unit area.

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125. What is linear charge density symbol?

Answer: $\lambda$
Explanation: Charge per unit length.

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126. What is volume charge density symbol?

Answer: $\rho$
Explanation: Charge per unit volume.

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127. What is Gauss’s law in integral form?

Answer:
$\oint \vec{E}\cdot d\vec{A}=\frac{Q}{{\epsilon }_0}$
Explanation: Total flux through closed surface.

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128. What is electric flux symbol?

Answer: $\mathrm{\Phi }$
Explanation: Represents total field lines.

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129. What is unit of electric flux?

Answer: Nm²/C
Explanation: Derived unit.

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130. What is significance of Gauss’s law?

Answer: Relates charge with electric field.
Explanation: Simplifies calculations.

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131. What is electric field due to charged conductor surface?

Answer:

$$E=\frac{\sigma }{{\epsilon }_0}$$

Explanation: Just outside the surface.

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132. What is field inside cavity of conductor?

Answer: Zero
Explanation: Due to electrostatic shielding.

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133. What is charge distribution in conductor at equilibrium?

Answer: On surface only.
Explanation: Charges repel outward.

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134. What is electrostatic equilibrium?

Answer: State where charges are at rest.
Explanation: No net force acts.

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135. What is electric potential of conductor?

Answer: Same everywhere.
Explanation: Equipotential body.

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136. What is potential difference between two points on conductor?

Answer: Zero
Explanation: No work needed.

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137. What is electric field just inside conductor?

Answer: Zero
Explanation: Internal field cancels.

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138. What is electric field just outside conductor?

Answer: Non-zero
Explanation: Depends on surface charge.

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139. What is relation between field and surface charge?

Answer:

$$E\propto \sigma$$

Explanation: Higher charge → stronger field.

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140. What is electrostatic force nature?

Answer: Conservative force
Explanation: Work done is path independent.

141. What is relation between electric field and potential difference?

Answer:
$E=-\frac{dV}{dx}$
Explanation: Field is rate of change of potential.

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142. What is potential difference in uniform field?

Answer:
$V=Ed$
Explanation: $d$ = separation distance.

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143. What is work done in moving charge in electric field?

Answer:
$W=qV$
Explanation: Depends on charge and potential.

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144. What is electric potential energy of charge in field?

Answer:

$$U=qV$$

Explanation: Energy stored due to position.

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145. What is unit of electric potential energy?

Answer: Joule (J)
Explanation: Same as energy unit.

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146. What is nature of electrostatic force?

Answer: Conservative
Explanation: Work depends only on initial and final positions.

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147. What is potential energy at infinite separation?

Answer: Zero
Explanation: Reference level.

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148. What is potential due to dipole on equatorial line?

Answer: Zero
Explanation: Contributions cancel.

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149. What is electric field at equatorial line of dipole direction?

Answer: Opposite to dipole moment
Explanation: Due to vector nature.

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150. What is electric field at axial line direction?

Answer: Along dipole moment
Explanation: Fields add in same direction.

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151. What is capacitance of isolated sphere?

Answer:
$C=4\pi {\epsilon }_{0}R$
Explanation: Depends on radius $R$.

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152. What is energy density in electric field?

Answer: Energy per unit volume.
Explanation: Stored in field.

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153. Write formula for energy density.

Answer:
$u=\frac{1}{2}{\epsilon }_0{E}^2$
Explanation: Depends on electric field.

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154. What is potential inside charged sphere?

Answer: Constant
Explanation: Same everywhere inside conductor.

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155. What is electric field inside charged sphere?

Answer: Zero
Explanation: Charges reside on surface.

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156. What is electric field outside sphere?

Answer: Same as point charge.
Explanation: Acts as if charge at center.

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157. What is capacitance of parallel plate with dielectric?

Answer:
$C=K\frac{{\epsilon }_{0}A}{d}$
Explanation: $K$ = dielectric constant.

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158. What is breakdown voltage?

Answer: Voltage at which dielectric fails.
Explanation: Causes conduction.

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159. What is electric field at sharp points of conductor?

Answer: Very high
Explanation: Due to high charge concentration.

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160. Why lightning rods are pointed?

Answer: To concentrate charge and discharge safely.
Explanation: Sharp points increase electric field.

161. What is relation between capacitance and potential?

Answer:
$C=\frac{Q}{V}$
Explanation: Capacitance depends on charge stored per unit potential.

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162. What is effect of increasing voltage on capacitance?

Answer: No effect
Explanation: Capacitance depends on geometry, not voltage.

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163. What is electric field in terms of potential difference and distance?

Answer:
$E=\frac{V}{d}$
Explanation: For uniform electric field.

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164. What is work done moving charge between two points?

Answer:
$W=q(V_1-V_2)$
Explanation: Depends on potential difference.

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165. What is energy stored per unit charge?

Answer: Electric potential
Explanation: Defined as $V=\frac{W}{q}$

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166. What is potential at center of ring?

Answer: Maximum
Explanation: All charges contribute equally.

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167. What is electric field at center of ring?

Answer: Zero
Explanation: Symmetry cancels field.

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168. What is electric field at center of charged shell?

Answer: Zero
Explanation: Due to symmetry and Gauss law.

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169. What is potential inside charged shell?

Answer: Constant
Explanation: Same as surface potential.

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170. What is effect of increasing dielectric constant?

Answer: Capacitance increases
Explanation: Electric field reduces.

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171. What is polarization direction in dielectric?

Answer: Along electric field
Explanation: Dipoles align with field.

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172. What is induced charge?

Answer: Charge developed due to external field.
Explanation: Happens without contact.

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173. What is relation between polarization and field?

Answer: Directly proportional
Explanation: Stronger field → more alignment.

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174. What is electric susceptibility?

Answer: Measure of polarization.
Explanation: Depends on material.

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175. What is relation between dielectric constant and susceptibility?

Answer:
$K=1+\chi$
Explanation: $\chi$ = susceptibility.

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176. What is electric displacement vector?

Answer: Total electric effect in medium.
Explanation: Includes free and bound charges.

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177. Write formula for electric displacement.

Answer:
$D={\epsilon }_{0}E+P$
Explanation: $P$ = polarization.

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178. What is unit of electric displacement?

Answer: C/m²
Explanation: Same as surface charge density.

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179. What is boundary condition for electric field?

Answer: Normal component changes.
Explanation: Depends on surface charge.

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180. What is tangential component of electric field at boundary?

Answer: Continuous
Explanation: Does not change across boundary.

181. What is electric field due to spherical shell (outside)?

Answer:

$E=k\frac{q}{r^2}$

$q_1$

$q_2$

$r$

$F=k\frac{q_1{q}_2}{r^2}\approx -5.06$

Charge and distance sliders update Coulomb force magnitude and direction.

Explanation: Acts like a point charge at center.

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182. What is electric field inside spherical shell?

Answer: Zero
Explanation: Due to symmetry and Gauss law.

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183. What is potential outside spherical shell?

Answer:
$V=k\frac{q}{r}$
Explanation: Same as point charge.

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184. What is potential inside spherical shell?

Answer: Constant
Explanation: Equal to surface potential.

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185. What is relation between electric field and charge density?

Answer: Directly proportional
Explanation: More charge → stronger field.

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186. What is Gauss law useful for?

Answer: Finding electric field easily.
Explanation: Works for symmetric systems.

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187. What is electric field due to infinite wire dependence?

Answer: Inversely proportional to distance.
Explanation: $E\propto \frac{1}{r}$

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188. What is electric field due to plane sheet dependence?

Answer: Independent of distance.
Explanation: Remains constant.

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189. What is direction of electric field at surface of conductor?

Answer: Perpendicular
Explanation: No tangential component exists.

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190. What happens if tangential field exists on conductor?

Answer: Charges move
Explanation: Violates electrostatic equilibrium.

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191. What is work done in closed path in electrostatics?

Answer: Zero
Explanation: Conservative field.

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192. What is curl of electrostatic field?

Answer: Zero
Explanation: Irrotational field.

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193. What is divergence of electric field?

Answer: Proportional to charge density
Explanation: From Gauss law.

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194. What is relation for divergence?

Answer:
$\mathrm{\nabla }\cdot E=\frac{\rho }{{\epsilon }_0}$
Explanation: Fundamental equation.

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195. What is potential gradient direction?

Answer: Opposite to electric field
Explanation: Negative sign relation.

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196. What is electric field between capacitor plates?

Answer: Uniform
Explanation: Same everywhere between plates.

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197. What is capacitance when plates are closer?

Answer: Increases
Explanation: $C\propto \frac{1}{d}$

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198. What is capacitance when area increases?

Answer: Increases
Explanation: $C\propto A$

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199. What is energy stored in capacitor dependence?

Answer: On capacitance and voltage
Explanation: $U\propto C{V}^2$

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200. What is importance of electrostatics?

Answer: Basis of many electrical devices.
Explanation: Used in capacitors, printers, etc.