Name: Hazards from Radioactive Material
Uploaded: 2019-07-19
Duration: 4 min 7 s
Description: Radiation hazard means the danger to the health of an individual arising from exposure to ionising radiation. Let's watch the video and learn.

Question

Draw a neat and labelled diagram of a box-type solar cooker. Write its (a) construction (b) working (c) advantage (d) limitations.

Accepted Answer

The diagram of a box-type solar cooker is as under:

Box type solar cooker:- A device which is used to cook food by utilising the infrared radiations coming from the sun is called solar cooker.

(a) Construction: A solar cooker consists of a wooden box (or plastic or fibreglass) which has an open-top. Thermocol lining is provided inside the wooden box for thermal insulation. The inside of the thermocol is painted black so that heat radiation is absorbed with high efficiency. A glass sheet is kept on the wooden box. A plane mirror (reflector) is hinged on the top of the solar cooker as shown. This arrangement is provided to change the direction of the plane mirror towards the sun from time to time. The plane mirror is so adjusted that radiations falling on the plane mirror, after reflection should pass through the glass sheet inside the wooden box.

(b) Working: The food to be cooked is kept in a container with an outer surface which is painted black. The container is kept inside the wooden box and covered with the glass sheet. The solar cooker is kept in sunlight and the reflector is adjusted so that a strong beam of sun rays fall on the top of the glass sheet after reflection from the plane mirror.
The sun rays penetrate the glass sheet and these radiations are absorbed by the black container. The temperature attained inside the solar cooker is $100 ° C - 140 ° C$ , when kept in the sun for $2 - 3$ hours. This temperature range is appropriate for cooking of rice, vegetables and pulses which require slow heating. The solar cooker is generally provided with $3$ to $4$ containers so that $3$ to $4$ food items are prepared simultaneously.

(c) Advantages of solar cooker:

The energy used is free of cost and pollution-free.

More than one food item can be cooked simultaneously.

When vegetables/pulses are cooked at a high temperature, a number of nutrients are lost which is not the case in a solar cooker.

(d) Disadvantages of solar cooker:

It cannot be used at night and on cloudy days.

The position of the solar cooker and reflector needs to be changed from time to time so that it faces the sun.

It cannot be used for high-temperature cooking applications like making chapatis, frying or baking.

It also takes more time for cooking as compared to a gas stove.

Draw a neat and labelled diagram of a box-type solar cooker. Write its (a) construction (b) working (c) advantage (d) limitations.

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