SOLAR COOKER AND SOLAR CELL

                                  

                    solar cooker

It is a device which converts solar energy directly into heat energy.

diagram-

                         

MATERIAL REQUIRED

 

-A solar cooker cover is lined with reflective material like mirror to reflect sun radiations into the box,where food containing utensil is placed.

-Glass cover(see the img.) is used to trap sun radiations.Glass sheets have a property that they allow radiations of small wavelengths to pass through them but do not allow radiations of large wavelengths to pass through them.

-Insulated lining such as black coloured thermocol is kept under containers to absorb sun radiations.

-The box is coloured black from inside to absorb the heat.

PROCESS

When sun radiations of small wavelengths come towards mirror, the mirror reflects them.Radiations fall on glass cover and pass into the box.The thermocol absorbs the heat of these radiations.When the sun radiations reflect back from here they are of large wavelengths, that is why glass does not allow these to pass  away and the radiations get trapped in the container.So in this way heat is used to cook the food.

ADVANTAGES

-Free of cost

-Pollution free

-no lose of nutrients of the food because of low temperature.

-More than one food item can be cooked.

DISADVANTAGES

-Solar cookers don't work at night or on cloudy days.

 -Parabolic cookers can get dangerously hot. You need to wear sunglasses when looking into a solar cooker, since the sun's reflected rays can hurt your eyes. 

-Food takes a long time to cook in solar box cookers.

                                                           SOLAR CELL

A device which converts solar energy directly into electricity.

diagram-

                          

ADVANTAGES

-It has long life.

-Pollution free

-Requires low maintenance as it has no moving parts.

-Good choice for remote areas.

DISADVANTAGES

-Costly because a highly purified silicon is used as semiconductor to convert infra red waves into electricity.

-Solar cells are connected by using silver wires ,which is very costly,to reduce loss of energy due to

   resistance.

-Used for charging storage batteries,which give direct current.This d.c. can be converted into A.C. through inverter.