☀️ Sources of Energy
Solar Energy and Solar Cooker | Class 10 Science | CBSE + Foundation + Competitive
☀️ Sources of Energy | Solar Energy and Solar Cooker
1. Introduction | परिचय
Solar energy is the energy received from the Sun in the form of electromagnetic radiation. It is the ultimate source of energy for most natural processes on Earth.
हिंदी: सौर ऊर्जा सूर्य से प्राप्त होने वाली ऊर्जा है। यह विद्युतचुंबकीय विकिरण के रूप में पृथ्वी तक पहुँचती है और पृथ्वी पर होने वाली अनेक प्राकृतिक प्रक्रियाओं के लिए ऊर्जा का प्रमुख स्रोत है।
Solar energy is a major renewable source of energy because sunlight is continuously supplied on a human timescale.
हिंदी: सौर ऊर्जा सूर्य से प्राप्त होने वाली ऊर्जा है। यह विद्युतचुंबकीय विकिरण के रूप में पृथ्वी तक पहुँचती है और पृथ्वी पर होने वाली अनेक प्राकृतिक प्रक्रियाओं के लिए ऊर्जा का प्रमुख स्रोत है।
Solar energy is a major renewable source of energy because sunlight is continuously supplied on a human timescale.
Exam Point: The Sun is the primary source of energy for most life and many energy resources on Earth.
2. What is Solar Energy?
Solar energy is the radiant energy emitted by the Sun.
It reaches Earth mainly as electromagnetic radiation, including visible light and infrared radiation.
Solar energy can be used directly or converted into other useful forms of energy.
Examples:
✔ Solar cooker
✔ Solar water heater
✔ Solar cell / photovoltaic panel
✔ Solar dryer
✔ Solar thermal power systems
Examples:
✔ Solar cooker
✔ Solar water heater
✔ Solar cell / photovoltaic panel
✔ Solar dryer
✔ Solar thermal power systems
3. Why is the Sun Important as an Energy Source?
The Sun provides the energy required for:
🌱 Photosynthesis in green plants
🌡️ Heating of the atmosphere and Earth's surface
💧 Water cycle
🌬️ Winds and atmospheric circulation
🌊 Ocean and weather processes
⚡ Generation of electricity through solar technologies
🌱 Photosynthesis in green plants
🌡️ Heating of the atmosphere and Earth's surface
💧 Water cycle
🌬️ Winds and atmospheric circulation
🌊 Ocean and weather processes
⚡ Generation of electricity through solar technologies
4. Solar Energy – Animated Diagram
5. Advantages of Solar Energy
| Advantage | Explanation |
|---|---|
| Renewable | Sunlight is continuously available on a human timescale. |
| Clean during operation | Solar devices generally produce no direct air pollution while operating. |
| Abundant | The Sun provides a huge amount of energy to Earth. |
| Useful in remote areas | Solar technologies can be useful where grid electricity is unavailable or limited. |
| Low operating emissions | Solar electricity has no fuel combustion during normal operation. |
6. Limitations of Solar Energy
Solar energy also has limitations:
❌ It depends on sunlight.
❌ Energy availability decreases during cloudy weather.
❌ No direct sunlight is available at night.
❌ Large collection areas may be required for significant energy output.
❌ Solar devices can have relatively high initial costs.
❌ Energy storage may be needed when sunlight is unavailable.
❌ It depends on sunlight.
❌ Energy availability decreases during cloudy weather.
❌ No direct sunlight is available at night.
❌ Large collection areas may be required for significant energy output.
❌ Solar devices can have relatively high initial costs.
❌ Energy storage may be needed when sunlight is unavailable.
7. Solar Cooker – Introduction
A solar cooker is a device that uses solar energy to heat and cook food.
It converts radiant energy from sunlight into thermal energy.
Solar cookers are especially useful in areas receiving strong sunlight.
हिंदी: सौर कुकर एक ऐसा उपकरण है जो सूर्य की ऊर्जा का उपयोग भोजन को गर्म करने और पकाने के लिए करता है।
हिंदी: सौर कुकर एक ऐसा उपकरण है जो सूर्य की ऊर्जा का उपयोग भोजन को गर्म करने और पकाने के लिए करता है।
8. Principle of Solar Cooker
A box-type solar cooker mainly works by:
1. Absorption of solar radiation
A black surface absorbs a large fraction of incident solar radiation.
2. Greenhouse effect
A transparent glass cover allows much of the incoming short-wave solar radiation to enter while reducing convective heat loss and helping retain thermal energy inside the box.
3. Reflection
A plane mirror or reflective surface may direct additional sunlight into the cooker.
1. Absorption of solar radiation
A black surface absorbs a large fraction of incident solar radiation.
2. Greenhouse effect
A transparent glass cover allows much of the incoming short-wave solar radiation to enter while reducing convective heat loss and helping retain thermal energy inside the box.
3. Reflection
A plane mirror or reflective surface may direct additional sunlight into the cooker.
Solar Radiation → Absorption → Heat → Cooking
9. Why is the Inside of a Solar Cooker Painted Black?
Question: Why are the inner surfaces of a solar cooker generally painted black?
Black surfaces are good absorbers of radiant energy. They absorb a large fraction of the incident solar radiation and convert it into thermal energy, increasing the temperature inside the cooker.
10. Why is a Glass Cover Used?
The transparent glass cover serves several purposes:
✔ Allows solar radiation to enter.
✔ Reduces heat loss by convection.
✔ Helps retain warm air inside the box.
✔ Contributes to the greenhouse effect.
✔ Protects the cooking chamber from wind and dust.
✔ Allows solar radiation to enter.
✔ Reduces heat loss by convection.
✔ Helps retain warm air inside the box.
✔ Contributes to the greenhouse effect.
✔ Protects the cooking chamber from wind and dust.
The glass cover does not simply “trap all radiation”. Its important role is to admit incoming sunlight and reduce heat loss, especially convective loss.
11. Why is a Plane Mirror Used?
A plane mirror can reflect additional sunlight into the cooking box.
Thus, the mirror increases the amount of solar radiation reaching the absorbing surface.
Key idea: Reflection helps redirect sunlight toward the cooker.
Key idea: Reflection helps redirect sunlight toward the cooker.
12. Solar Cooker – Labelled Diagram
13. How Does a Box-Type Solar Cooker Work?
Step 1: Solar radiation falls on the cooker.
Step 2: Sunlight enters through the transparent glass cover.
Step 3: The black inner surface absorbs solar radiation.
Step 4: The absorbed radiation is converted into thermal energy.
Step 5: The temperature inside the box rises.
Step 6: Food placed in the vessel absorbs heat and cooks.
Step 2: Sunlight enters through the transparent glass cover.
Step 3: The black inner surface absorbs solar radiation.
Step 4: The absorbed radiation is converted into thermal energy.
Step 5: The temperature inside the box rises.
Step 6: Food placed in the vessel absorbs heat and cooks.
Sunlight → Glass Cover → Black Surface → Heat → Food
14. Greenhouse Effect in a Solar Cooker
In a box-type solar cooker, the glass cover allows incoming solar radiation to enter and helps reduce heat loss from the hot interior.
This causes the temperature inside the cooker to rise above the surrounding temperature.
This is commonly explained using the greenhouse effect.
15. Why is a Solar Cooker Not Usually Used at Night?
Answer:
A solar cooker depends directly on solar radiation. At night there is no direct sunlight available to provide the required heating energy.
Therefore, without stored heat or another energy source, ordinary solar cookers cannot cook food effectively at night.
16. Why Does a Solar Cooker Work Better on a Sunny Day?
A sunny day provides stronger and more continuous solar radiation.
Therefore:
More solar radiation → More absorbed energy → Higher temperature → Faster cooking
More solar radiation → More absorbed energy → Higher temperature → Faster cooking
17. Why is a Solar Cooker Less Effective on a Cloudy Day?
Clouds reduce the intensity of direct solar radiation reaching the cooker.
Therefore the cooker receives less radiant energy and generally reaches a lower temperature.
18. Important Features of a Box-Type Solar Cooker
| Part | Function |
|---|---|
| Glass cover | Allows sunlight to enter and reduces heat loss, especially by convection. |
| Black inner surface | Absorbs solar radiation and converts it into heat. |
| Cooking vessel | Contains the food to be cooked. |
| Insulation | Reduces heat loss from the cooker walls. |
| Plane mirror | Reflects additional sunlight toward the cooker. |
19. Solar Cooker vs Solar Cell
| Solar Cooker | Solar Cell |
|---|---|
| Converts solar radiation mainly into heat. | Converts solar radiation directly into electrical energy. |
| Used for cooking/heating. | Used for generating electricity. |
| Works through absorption and thermal processes. | Works through the photovoltaic effect. |
20. Solar Thermal Energy vs Solar Photovoltaic Energy
| Solar Thermal | Solar Photovoltaic |
|---|---|
| Solar energy is converted into thermal energy. | Solar energy is converted directly into electrical energy. |
| Example: Solar cooker. | Example: Solar cell/panel. |
| Useful for heating and cooking. | Useful for electricity generation. |
21. Environmental Benefits
✔ Reduces dependence on conventional fuels for suitable applications.
✔ Solar cooker does not require combustion of wood, coal or LPG during operation.
✔ Helps reduce direct emissions associated with fuel combustion.
✔ Uses a renewable source of energy.
✔ Can help conserve conventional fuels when appropriately used.
✔ Solar cooker does not require combustion of wood, coal or LPG during operation.
✔ Helps reduce direct emissions associated with fuel combustion.
✔ Uses a renewable source of energy.
✔ Can help conserve conventional fuels when appropriately used.
22. Limitations of a Solar Cooker
❌ Depends on sunlight.
❌ Cannot normally be used effectively at night without another heat source.
❌ Cloudy or rainy weather reduces performance.
❌ Cooking may take longer than conventional high-power heating methods.
❌ Some foods and cooking methods are less suitable.
❌ Requires proper positioning toward the Sun.
❌ Cannot normally be used effectively at night without another heat source.
❌ Cloudy or rainy weather reduces performance.
❌ Cooking may take longer than conventional high-power heating methods.
❌ Some foods and cooking methods are less suitable.
❌ Requires proper positioning toward the Sun.
23. Important Definitions
| Term | Definition |
|---|---|
| Solar Energy | Radiant energy received from the Sun. |
| Solar Cooker | Device that uses solar radiation to cook food. |
| Renewable Source | An energy source naturally replenished on a human timescale. |
| Solar Radiation | Electromagnetic radiation emitted by the Sun. |
| Greenhouse Effect | Retention of thermal energy due to selective transmission and reduced heat loss. |
| Photovoltaic Effect | Generation of electrical potential/current from light in suitable materials. |
24. 30 MCQs | Multiple Choice Questions
1. Solar energy is obtained from:
A. Sun
B. Moon
C. Earth’s core only
D. Ocean floor
Answer: A
2. Solar energy is mainly a:
A. Non-renewable source
B. Renewable source
C. Fossil fuel
D. Nuclear fuel
Answer: B
3. A solar cooker converts solar energy mainly into:
A. Sound energy
B. Chemical energy
C. Heat energy
D. Nuclear energy
Answer: C
4. The inner surface of a box-type solar cooker is generally:
A. White
B. Transparent
C. Shiny silver
D. Black
Answer: D
5. Black surfaces are used because they are good:
A. Absorbers of radiation
B. Reflectors only
C. Insulators of light
D. Sources of sunlight
Answer: A
6. The transparent cover of a solar cooker is usually made of:
A. Wood
B. Glass
C. Rubber
D. Brick
Answer: B
7. A plane mirror in a solar cooker helps by:
A. Producing electricity
B. Cooling the cooker
C. Reflecting additional sunlight into the cooker
D. Blocking all radiation
Answer: C
8. The glass cover mainly helps to:
A. Reduce heat loss and allow sunlight to enter
B. Produce fuel
C. Stop all sunlight
D. Generate magnetic fields
Answer: A
9. The greenhouse effect in a solar cooker helps to:
A. Decrease the temperature
B. Increase heat retention
C. Produce coal
D. Stop absorption
Answer: B
10. Which is a limitation of solar energy?
A. It is renewable
B. It is abundant
C. It depends on sunlight availability
D. It can be used for heating
Answer: C
11. Solar cooker works best when:
A. Strong sunlight is available
B. It is completely dark
C. Heavy clouds block sunlight
D. It is kept indoors
Answer: A
12. Solar cells convert solar energy mainly into:
A. Heat
B. Electrical energy
C. Sound
D. Mechanical energy only
Answer: B
13. The process used by solar cells is called:
A. Electrolysis
B. Fermentation
C. Photovoltaic effect
D. Nuclear fission
Answer: C
14. Solar cooker is an example of:
A. Solar thermal application
B. Nuclear application
C. Fossil-fuel technology
D. Magnetic induction
Answer: A
15. Solar energy reaches Earth mainly as:
A. Electromagnetic radiation
B. Sound waves
C. Mechanical waves only
D. Water waves
Answer: A
16. Which process allows plants to capture solar energy?
A. Respiration
B. Photosynthesis
C. Digestion
D. Excretion
Answer: B
17. Solar energy is considered renewable because:
A. It comes from coal
B. It is continuously supplied by the Sun
C. It is stored underground forever
D. It cannot be used again
Answer: B
18. Which surface absorbs a large fraction of incident solar radiation?
A. Black surface
B. Polished silver surface
C. Transparent glass only
D. White paper only
Answer: A
19. A solar cooker cannot normally operate effectively at night because:
A. There is no direct solar radiation
B. Gravity disappears
C. Glass stops working
D. Black surfaces become white
Answer: A
20. Insulation in a solar cooker helps to:
A. Increase heat loss
B. Reduce heat loss
C. Stop sunlight completely
D. Produce electricity
Answer: B
21. Which is NOT a major advantage of solar energy?
A. Renewable nature
B. Availability of sunlight
C. Direct dependence on fossil fuels
D. Low direct emissions during operation
Answer: C
22. A cloudy day generally causes a solar cooker to:
A. Receive less solar radiation
B. Receive more sunlight
C. Become a refrigerator
D. Produce more fuel
Answer: A
23. The main energy input into a solar cooker is:
A. Solar radiation
B. Electricity from grid
C. Coal
D. Petrol
Answer: A
24. Which component contains the food?
A. Mirror
B. Cooking vessel
C. Glass cover only
D. Outer insulation
Answer: B
25. The main purpose of a reflective surface is to:
A. Redirect solar radiation
B. Absorb all heat
C. Stop cooking
D. Reduce sunlight
Answer: A
26. Which statement is correct?
A. Solar energy is non-renewable
B. Solar cooker uses combustion
C. Solar cooker converts radiation into heat
D. Solar cooker requires coal
Answer: C
27. Solar thermal technology mainly produces:
A. Thermal energy
B. Nuclear energy
C. Sound energy
D. Chemical fuel
Answer: A
28. Which is a direct use of solar thermal energy?
A. Solar cooker
B. Coal mine
C. Petrol engine
D. Diesel generator
Answer: A
29. Which factor can reduce the performance of a solar cooker?
A. Strong sunlight
B. Proper orientation
C. Heavy cloud cover
D. Good insulation
Answer: C
30. The best summary of a box-type solar cooker is:
A. It burns fuel to produce heat
B. It uses sunlight, absorption and heat retention for cooking
C. It uses only electricity
D. It uses nuclear energy
Answer: B
25. Subjective Questions | 2, 3, 4, 5 & 6 Marks
2 Marks
Q1. What is solar energy?
Solar energy is the radiant energy received from the Sun in the form of electromagnetic radiation.
2 Marks
Q2. Why is solar energy called renewable?
Because sunlight is continuously supplied by the Sun and is naturally replenished on a human timescale.
2 Marks
Q3. What is a solar cooker?
A solar cooker is a device that uses solar radiation to produce heat for cooking food.
2 Marks
Q4. Why is the inside of a solar cooker black?
Black surfaces absorb a large fraction of incident solar radiation and convert it into thermal energy.
2 Marks
Q5. What is the function of the glass cover?
It allows sunlight to enter and reduces heat loss, especially convective heat loss, helping maintain a high temperature inside.
3 Marks
Q6. State three advantages of solar energy.
1. It is renewable.
2. It is abundant.
3. Solar technologies can operate without fuel combustion during normal operation.
2. It is abundant.
3. Solar technologies can operate without fuel combustion during normal operation.
3 Marks
Q7. Why is a plane mirror used in a solar cooker?
A plane mirror reflects sunlight and directs additional solar radiation toward the cooking chamber, increasing the energy received.
3 Marks
Q8. Why does a solar cooker work poorly on cloudy days?
Clouds reduce the solar radiation reaching the cooker. Consequently, less energy is absorbed and the cooker reaches a lower temperature.
3 Marks
Q9. What is meant by the greenhouse effect in a solar cooker?
The glass cover allows incoming sunlight to enter while helping reduce heat loss from the heated interior, causing temperature to rise.
3 Marks
Q10. Distinguish between a solar cooker and a solar cell.
A solar cooker converts solar radiation mainly into heat, whereas a solar cell converts solar radiation into electrical energy through the photovoltaic effect.
4 Marks
Q11. Explain the working of a box-type solar cooker.
Sunlight enters through the transparent cover. The black surface absorbs the radiation and converts it into heat. The glass cover and insulation reduce heat loss. The cooking vessel absorbs heat and cooks the food.
4 Marks
Q12. Write four limitations of solar energy.
1. Depends on sunlight.
2. Reduced performance during cloudy weather.
3. No direct sunlight at night.
4. Storage or backup may be required for continuous energy supply.
2. Reduced performance during cloudy weather.
3. No direct sunlight at night.
4. Storage or backup may be required for continuous energy supply.
4 Marks
Q13. Explain the role of black surface, glass cover, insulation and mirror.
Black surface absorbs radiation; glass cover admits sunlight and reduces heat loss; insulation reduces heat loss through the walls; mirror reflects additional sunlight into the cooker.
4 Marks
Q14. Why is solar energy considered environmentally useful?
It is renewable and solar devices do not require combustion of fuel during normal operation. Thus they can reduce direct emissions associated with burning conventional fuels.
5 Marks
Q15. Explain the principle of a solar cooker.
A solar cooker receives solar radiation through a transparent cover. A black absorbing surface converts the radiation into heat. A mirror may reflect additional sunlight into the box. Insulation and the cover reduce heat loss, causing the internal temperature to rise and cook food.
5 Marks
Q16. Explain why the temperature inside a solar cooker becomes high.
Solar radiation enters through the transparent cover and is absorbed by the black surface. The absorbed radiation becomes thermal energy. The cover and insulation reduce heat loss, so thermal energy accumulates and the internal temperature rises.
5 Marks
Q17. Compare solar thermal and photovoltaic technologies.
Solar thermal technology converts solar radiation into heat, as in solar cookers and water heaters. Photovoltaic technology converts solar radiation directly into electrical energy using solar cells.
5 Marks
Q18. Explain four advantages and four limitations of solar energy.
Advantages: renewable, abundant, low direct emissions during operation and useful in remote areas. Limitations: depends on sunlight, weather-dependent, unavailable directly at night and may require storage or backup.
6 Marks
Q19. Draw and explain a box-type solar cooker.
A box-type solar cooker contains a dark absorbing surface, cooking vessel, transparent glass cover and insulation. A plane mirror may be attached to reflect additional sunlight. Sunlight enters through the cover, is absorbed by the black surface and converted to heat. The cover and insulation reduce heat loss, allowing food to cook.
6 Marks
Q20. Explain how different parts of a solar cooker improve its efficiency.
The black surface improves absorption. The glass cover allows sunlight to enter and reduces convective heat loss. Insulation reduces heat loss through the walls. A mirror can direct additional radiation into the cooker. Together these features increase the temperature available for cooking.
6 Marks
Q21. Why is solar energy important as a future energy source?
Solar energy is renewable and widely available. It can be used for heating, cooking and electricity generation. It can reduce dependence on finite fossil fuels and, during operation, solar technologies do not require fuel combustion.
6 Marks
Q22. Explain the conversion of solar radiation into heat in a solar cooker.
Solar radiation enters through the transparent cover. The black absorbing surface absorbs the radiation and converts it into thermal energy. Heat is transferred to the cooking vessel and food. The glass cover and insulation reduce heat loss so that the temperature rises.
6 Marks
Q23. Explain why a solar cooker cannot replace all conventional cooking systems.
Its operation depends on sunlight and weather conditions. It is not normally effective at night without another energy source, may cook more slowly and is not suitable for every cooking method. Therefore it is useful for suitable applications but does not replace all cooking systems.
6 Marks
Q24. Explain the environmental significance of solar cookers.
Solar cookers use sunlight instead of burning conventional fuels during operation. They can reduce the consumption of firewood or other fuels for suitable cooking tasks and therefore can reduce direct emissions associated with fuel combustion.
6 Marks
Q25. Explain the importance of the Sun in an ecosystem and energy resources.
Sunlight provides energy for photosynthesis, through which producers form organic food. This energy enters food chains and supports consumers. Solar radiation also drives atmospheric and water-cycle processes and can be directly harnessed using solar technologies.
6 Marks
Q26. Explain the greenhouse effect of a solar cooker carefully.
The transparent cover allows incoming solar radiation to enter the cooking chamber while helping reduce heat loss from the hot interior, particularly by limiting convection. Consequently heat accumulates and the temperature inside increases.
6 Marks
Q27. Compare renewable and non-renewable energy sources with examples.
Renewable sources are replenished naturally on a human timescale, such as solar, wind and hydro energy. Non-renewable sources exist in limited reserves and are consumed faster than natural processes replenish them, such as coal, petroleum and natural gas.
6 Marks
Q28. Why should a solar cooker be properly oriented toward the Sun?
Proper orientation helps the cooker receive more direct solar radiation. Greater incident radiation generally increases the absorbed energy and therefore improves heating and cooking performance.
6 Marks
Q29. Explain the difference between reflection and absorption in a solar cooker.
Reflection redirects incident solar radiation, as done by a mirror. Absorption occurs when the black surface takes in radiation and converts it into thermal energy. Both processes can help improve solar heating.
6 Marks
Q30. Write a complete note on Solar Energy and Solar Cooker.
Solar energy is radiant energy from the Sun and is a major renewable energy source. It can be used for heating and electricity generation. A box-type solar cooker uses a transparent cover, black absorbing surface, insulation and sometimes a plane mirror. Sunlight enters the box, the black surface absorbs it and converts it into heat, while the cover and insulation reduce heat loss. Solar cookers are clean during operation but depend on sunlight and weather conditions.
26. Assertion–Reason
Assertion (A): The inner surface of a solar cooker is generally black.
Reason (R): Black surfaces absorb a large fraction of incident radiation.
Reason (R): Black surfaces absorb a large fraction of incident radiation.
Answer: Both A and R are true, and R correctly explains A.
Assertion (A): Solar cookers work better under strong sunlight.
Reason (R): Strong sunlight provides greater solar radiation to the cooker.
Reason (R): Strong sunlight provides greater solar radiation to the cooker.
Answer: Both A and R are true, and R correctly explains A.
Assertion (A): A solar cooker can normally cook food at night without any stored energy or backup.
Reason (R): Solar cookers depend on solar radiation.
Reason (R): Solar cookers depend on solar radiation.
Answer: Assertion is false, but Reason is true.
Assertion (A): A plane mirror can improve solar cooker performance.
Reason (R): A mirror can reflect additional sunlight toward the cooker.
Reason (R): A mirror can reflect additional sunlight toward the cooker.
Answer: Both A and R are true, and R correctly explains A.
Assertion (A): Solar energy is a renewable source.
Reason (R): Sunlight is naturally replenished continuously on a human timescale.
Reason (R): Sunlight is naturally replenished continuously on a human timescale.
Answer: Both A and R are true, and R correctly explains A.
27. HOTS | Higher Order Thinking
HOTS 1: Why would painting the inside of a solar cooker white generally reduce its heating performance?
A white surface generally reflects more incident visible radiation than a black absorbing surface, so less solar radiation would be converted into heat.
HOTS 2: A solar cooker is placed under a tree on a sunny day. Why will its performance decrease?
The tree blocks part of the incident solar radiation, reducing the energy reaching and being absorbed by the cooker.
HOTS 3: Why can insulation improve the cooking temperature?
Insulation reduces heat transfer from the hot interior to the surroundings, allowing more thermal energy to remain inside the cooker.
HOTS 4: Why is direct sunlight generally more useful for a solar cooker than weak diffuse light?
Direct sunlight can provide greater irradiance on the cooker, increasing the rate at which solar energy is received and absorbed.
HOTS 5: Suggest four ways to improve the performance of a box-type solar cooker.
Use a good black absorber, effective insulation, a clean transparent cover and proper orientation toward the Sun. A suitable reflector can also increase incident radiation.
28. Golden Points | परीक्षा के लिए
☀️ Solar energy = radiant energy from Sun.
♻️ Solar energy = renewable source.
🍳 Solar cooker converts solar radiation mainly into heat.
⬛ Black surface = good absorber.
🪟 Glass cover = sunlight enters + heat loss reduced.
🪞 Mirror = reflects additional sunlight.
🧱 Insulation = reduces heat loss.
🌧️ Cloudy weather = lower solar input.
🌙 Night = no direct solar radiation.
⚡ Solar cell = photovoltaic conversion to electricity.
♻️ Solar energy = renewable source.
🍳 Solar cooker converts solar radiation mainly into heat.
⬛ Black surface = good absorber.
🪟 Glass cover = sunlight enters + heat loss reduced.
🪞 Mirror = reflects additional sunlight.
🧱 Insulation = reduces heat loss.
🌧️ Cloudy weather = lower solar input.
🌙 Night = no direct solar radiation.
⚡ Solar cell = photovoltaic conversion to electricity.
29. One-Minute Revision
☀️ SUN
↓ Solar Radiation
↓ 🪟 Glass Cover
↓ ⬛ Black Absorber
↓ 🔥 Heat
↓ 🍳 Cooking
↓ Solar Radiation
↓ 🪟 Glass Cover
↓ ⬛ Black Absorber
↓ 🔥 Heat
↓ 🍳 Cooking
Memory Trick:
BLACK → ABSORB
MIRROR → REFLECT
GLASS → ENTER + RETAIN HEAT
INSULATION → REDUCE HEAT LOSS
SUN → ENERGY SOURCE
BLACK → ABSORB
MIRROR → REFLECT
GLASS → ENTER + RETAIN HEAT
INSULATION → REDUCE HEAT LOSS
SUN → ENERGY SOURCE
30. Concept Map
31. Final Summary
Solar energy is the radiant energy received from the Sun and is one of the most important renewable energy resources.
A solar cooker uses solar radiation to produce heat for cooking.
The important components of a box-type solar cooker are:
✔ Transparent glass cover
✔ Black absorbing surface
✔ Cooking vessel
✔ Insulation
✔ Plane mirror, where provided
The basic energy conversion is:
Solar radiation → Absorption → Thermal energy → Cooking
The black surface increases absorption, the glass cover helps reduce heat loss, insulation reduces heat loss through the walls, and a mirror can reflect additional sunlight toward the cooker.
Most important exam line:
☀️ A solar cooker converts solar radiation into thermal energy and uses that heat for cooking.
A solar cooker uses solar radiation to produce heat for cooking.
The important components of a box-type solar cooker are:
✔ Transparent glass cover
✔ Black absorbing surface
✔ Cooking vessel
✔ Insulation
✔ Plane mirror, where provided
The basic energy conversion is:
Solar radiation → Absorption → Thermal energy → Cooking
The black surface increases absorption, the glass cover helps reduce heat loss, insulation reduces heat loss through the walls, and a mirror can reflect additional sunlight toward the cooker.
Most important exam line:
☀️ A solar cooker converts solar radiation into thermal energy and uses that heat for cooking.
☀️ Class 10 Science | Sources of Energy
Solar Energy • Solar Cooker • Renewable Energy • Greenhouse Effect • Solar Thermal Energy
CBSE + Foundation + Competitive Preparation
Solar Energy • Solar Cooker • Renewable Energy • Greenhouse Effect • Solar Thermal Energy
CBSE + Foundation + Competitive Preparation
