[Physics Class Notes] on Uses of Solar Cooker Pdf for Exam

A solar cooker is a very efficient device. It does not cause air pollution and saves the natural fossil fuel of the earth. This device uses solar energy to cook food. The concept behind this device is that a concave surface reflects and focuses the sun’s heat. The amount of heat is quite large to be able to cook the food. There are three hundred models of solar cookers presently. They range from absolute simple designs to very complicated and advanced technologies. Usually, the largest used solar cookers are simple to build and very cheap. Solar cooking is a solution for people who don’t have access to fuel for cooking. This technology is a boon for them. Moreover, the more we harvest solar energy for cooking, the more clean, fresh, and unpolluted air we breathe. The raw food items are cut into small pieces while cooking. The various uses of the cooker are:

• A solar cooker requires a limited quantity of water to cook the food. 

•  The water gets evaporated and then recaptured as freshwater. The solar ultraviolet rays kill the DNA linkages in microorganisms and hence purify the water. Thus water gets distilled.

• Iron ore smelting using solar power does not involve the emission of excess carbon dioxide into the atmosphere and hence is a clean process.

• We can dehydrate the vegetables and other food items in the solar cooker or oven.

• The solar wax melter is a simple solar oven. It has a screen on which we place the raw-wax. It melts slowly and drips into the container below it. 

• Specially designed solar cookers are used in hospitals and clinics to sterilize their instruments. The doctors prefer using this device as it reduces pollution.

The Three Main Principles of a Solar Cooker

A solar cooker can work only in the daylight. At night it is useless and cannot serve its purpose. There are three main principles based on which the heating takes place in a solar cooker. These are;

• The concentration of heat on an object can only occur faster when the sun rays (UV) focus at a particular point. The solar cooker has a reflecting surface made from shiny reflecting material. Metals like chromium, silver, and aluminium constitute these reflecting surfaces.

•  Black colour absorbs more heat than any colour. Light colours reflect heat. Therefore, most solar cookers are coloured black so that they can absorb more heat to cook well. Also, these cookers are thin so that the heat gets transferred quickly and uniformly to the food.

• The solar cooker should be able to trap the heat which it has absorbed. Otherwise, the heat will escape from the food. It will not cook properly. For this reason, the cooker has a lid that tightly covers it. 

Solved Examples

1. How to Trap Heat in a Solar Cooker?

The solar cooker uses heat energy from the sun to cook food. The heating of these cookers takes place using simple phenomena called specular reflection. The angle of incidence of the light beam, focussed on the cooker, is equal to the angle of reflection. This phenomenon requires a very smooth surface. No light is scattered away in another direction. This phenomenon used to focus on the maximum heat at a particular point.

2. What are the Advantages of Using a Solar Cooker?

There are various kinds of solar cookers. Using them has several advantages;

• Using solar energy for cooking reduces the carbon footprint as no carbon-based fuels or current from the electricity grid is used.

• Using less fossil fuel saves the cost spent behind it. It also reduces deforestation and keeps the environment clean.

• Cooking can be done at temperatures above 290 degrees celsius with the help of the vacuum tube and parabolic solar cookers.

• The conventional solar box cookers can reach up to temperatures of 160 degrees that helps in cooking most food items like bread and vegetables. It also helps in the sterilization of food and instruments.