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Nature's Treasures - Energy from the Sun

Grade 6CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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The Sun is the ultimate source of energy for all life forms on Earth, providing energy in the form of heat and light.

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Green plants capture solar energy to prepare food through the process of Photosynthesis, converting light energy into chemical energy stored in glucose (C6H12O6C_6H_{12}O_6).

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Solar energy is a renewable and 'clean' source of energy because it does not produce greenhouse gases like carbon dioxide (CO2CO_2) during its use.

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Solar Cells (Photovoltaic cells) are devices that convert sunlight directly into electricity. A collection of these cells forms a Solar Panel.

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Solar Cookers and Solar Water Heaters use the Sun's thermal energy. They often use black surfaces to absorb maximum heat and mirrors to reflect sunlight onto a specific area.

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The Greenhouse Effect is the process where heat is trapped near Earth's surface by substances like CO2CO_2 and water vapor, maintaining a temperature suitable for life.

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Light from the Sun travels at a speed of approximately 3×108 m/s3 \times 10^8 \text{ m/s} and takes about 88 minutes and 2020 seconds (or 500 seconds500 \text{ seconds}) to reach the Earth.

📐Formulae

6CO2+6H2O+light energy→chlorophyllC6H12O6+6O26CO_2 + 6H_2O + \text{light energy} \xrightarrow{\text{chlorophyll}} C_6H_{12}O_6 + 6O_2

Distance=Speed×Time\text{Distance} = \text{Speed} \times \text{Time}

Efficiency=Output EnergyInput Energy×100%\text{Efficiency} = \frac{\text{Output Energy}}{\text{Input Energy}} \times 100\%

💡Examples

Problem 1:

If light travels from the Sun at a speed of 300,000 km/s300,000 \text{ km/s} and takes 500 seconds500 \text{ seconds} to reach the Earth, calculate the distance between the Sun and the Earth in kilometers.

Solution:

150,000,000 km150,000,000 \text{ km}

Explanation:

Using the formula Distance=Speed×Time\text{Distance} = \text{Speed} \times \text{Time}, we substitute the values: 300,000×500150,000,000\begin{array}{r} 300,000 \\ \times 500 \\ \hline 150,000,000 \end{array} So, the distance is 1.5×108 km1.5 \times 10^8 \text{ km}.

Problem 2:

Identify the energy conversion taking place in a Solar Cell and a Solar Cooker.

Solution:

Solar Cell: Light →\rightarrow Electrical; Solar Cooker: Light →\rightarrow Heat.

Explanation:

A Solar Cell uses the photovoltaic effect to turn light into electricity (DCDC). A Solar Cooker uses reflectors and absorbers to turn the Sun's radiation into thermal energy for cooking food.