Question

The kind of mirror most suited for use in solar cooker is:
A. Concave mirror
B. Convex mirror
C. Plane mirror
D. None of these

Answer 1

Hint: Solar cooker is a device used for cooking by trapping the sunrays, which heat up the food. If a large amount of rays can be captured, it will make the process of cooking faster.

Complete step by step answer:
Solar cooker is a device in which we can heat or cook food. One can say that it is an oven that works without electricity but it is not an oven. Solar cooker uses the heat of the sunrays to cook food. That is the reason why it is called a solar cooker. Sun emits thermal radiations which are electromagnetic waves belonging to the infrared region of the electromagnetic spectrum. These radiations transfer the electromagnetic energy. When a body absorbs these radiations, it heats up. This fact is used in the solar cooker. Let us understand how a simple solar cooker works. It is a box with black covering. Black coloured absorb most of the radiation incident on it. This way more heat will be produced. The cooking bowl inside is made up of transparent material so that it does not reflect the rays that fall on it and all the rays penetrate the bowl. The infrared rays vibrate the molecules of the food and the food gets heated up.
Now, to fasten the rate of cooking what we can do is to somehow make more number of rays to fall on the food. This can be done by somehow deflecting the sun rays towards the food. For these reasons mirrors are used to reflect the rays that are away from the food, on the food. The most suited mirror for this job will be a concave mirror since it is a converging mirror. A concave mirror converges the rays coming from a faraway distance, near its focus. Therefore, if we use a large concave mirror and keep the bowl near the focus of the mirror, all the rays falling on this mirror will be concentrated on the food which will increase the intensity of the heat.
Hence, the correct option is (b) convex mirror

Note: A plane mirror can be used in a solar cooker but it cannot concentrate the rays at point as the concave mirror does. Thus, the maximum heat will not be achieved. A convex cannot be at all since it will diverge away the sun rays falling on it.