CBSE · Class 10 · Science · Sources of EnergyExplain the construction and working of a solar cooker. Also, write two main advantages and two limitations of using a solar cooker.

Construction of a Solar Cooker\nA box-type solar cooker consists of the following main components:

• Insulated Box: A sturdy metal or plastic box painted black from the inside to absorb maximum heat. The space between the inner box and the outer box is filled with an insulating material like glass wool or cork to minimize heat loss.
• Plane Mirror Reflector: A plane glass mirror is attached to the lid of the box. It is adjusted to reflect sunlight into the interior of the box.
• Glass Sheet Cover: A double-glass lid covers the top of the box. This allows solar radiation to enter inside and traps the heat inside the box due to the greenhouse effect.
• Cooking Containers: Usually four blackened aluminium containers are placed inside the box to keep the food.

Working Principle and Process

• The solar cooker is placed in direct sunlight with its reflector adjusted so that maximum sunlight falls on the mirror and gets reflected into the box.
• The black interior of the box and the blackened outer surface of the cooking containers absorb the infrared and visible radiations from the sun, converting them into heat.
• The temperature inside the box rises up to 100°C to 140°C in a few hours.
• The trapped heat cannot escape easily because of the glass sheet cover, creating a greenhouse effect which cooks the food kept inside the containers efficiently.

Advantages

1. Eco-friendly: It does not cause any environmental pollution as it uses renewable solar energy without burning any fossil fuels.
2. Nutrient Retention: Food cooked in a solar cooker retains most of its nutrients because the cooking temperature is not excessively high.

Limitations

1. Weather Dependent: It cannot be used on cloudy days, during rainy seasons, or at night because it relies entirely on direct sunlight.
2. Time Consuming: The cooking process is very slow compared to conventional LPG gas stoves or electric cookers.