New trends in physics teaching, v.4; The ... - unesdoc - Unesco

A solar cooker
Let the reflector face the sun.
Q. 7 At what timeof the day and in what months of the year can you best use a solar cooker?
Q.8 Which people do you think will gain most in using solar cooker, those from the North
pole? South pole? or from the equator?
H. Bore a 0.6 cm diameter hole in the lids of the cans. Place about 300 ml of water in each can
and replace the lids. Next place a thermometer in each can.
I. Place one can inside the cooker and the other outside.
J. Adjust the reflector so that sunlight is reflected on to the can.
K. Record the temperature readings every 15 minutes. See to it that the reflection of sunlight
is focused on the can every time you take a reading.
Q.9 How do wind and clouds affect solar cooking?
L. Record your data in a table similar to table 1.
L
Time Temperature of water Temperature of water Weather condition
inside the cooker outside the cooker (cloudy, sunny, windy)
M. When the water reaches boiling point, it can be used for cooking.
Q. 10 How much energy was used in boiling the water?
Where did the energy come from? Hint: Use H = Cm A t
N. Carefully remove the can and thermometer inside the cooker and open it. Add about 50 ml
of tap water and 5 eggs. Take the thermometer away and replace the lid tightly.
0. Place the can with eggs inside the cooker.
P. After one hour, remove and taste the eggs.
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