Question

a.) Write the name of the device used to cook food using solar energy.
b.) What are the advantages and disadvantages of this device?

Answer 1

Hint: Recall that this device converts solar energy to heat energy and relies entirely on the amount of sunlight incident on it. Since they need to absorb sunlight, think of what kind of materials would be effective to do so and what other mechanisms they would need to trap heat. Also, since they are always used outdoors, think of the factors which affect outdoor cooking, in terms of weather, wind, and time of day.

Complete answer:
a.)The device that is used to cook food using solar energy, as the term suggests, is called a solar cooker.

A solar cooker works on the principle of conversion of solar energy to heat energy.
The driving fuel for solar cookers is the sunlight. They rely entirely on the amount of sunlight incident on the cooker area.

Solar cookers are generally made of dark coloured materials since dark surfaces absorb sunlight a lot more effectively than fainter coloured materials which end up reflected off light.

Solar cookers usually come equipped with a heat trap surrounding the pot of the cooker so that the pot retains all the heat produced by the incident sunlight. This is synonymous to a greenhouse where sunlight is let in but heat producing energetic light is retained inside and is not allowed out. The heat trap is usually a clear, heat-resistant plastic bag or a large inverted glass bowl.

Sometimes the solar cookers come equipped with one or more shiny surfaces that reflect extra or stray sunlight into the pot, or with solar panels, which help in increasing the potential of the cooker to produce heat.

b.)Let us now look at some advantages and disadvantages of this device:

Advantages:
1. They can be set up in remote places where electricity might not be available
2. They require very little user interference and are easy to use.
3. They are easy to maintain since they have no moving parts.
4. They are cost-effective as it involves no recurring expenses on fuel.
5. They are environmentally friendly and there is always an infinite source of energy.

Disadvantages:
1. They rely entirely on the weather, and require a clear sunny day for an optimal performance.
2. Their performance is reduced by the presence of strong winds due to convective heat loss.
3. Compared to conventional heating, solar cookers take more time to heat things up.
4. They cannot be used during the night time since they run on only sunlight.

Note:
Solar cookers are quite versatile and are used in many applications ranging from cooking food, distilling water and melting wax, to smelting (applying heat to an ore to extract a base metal), sterilization of medical equipment and separating beeswax from a honeycomb.
Modern solar cookers come a bit more advanced with solar panels and solar cells which are able to effectively receive sunlight without having to focus the rays and store the heat energy produced for later use. But they still underperform in contrast to conventional cooking devices and are usually more expensive.