Why is a sonometer box provided with holes?

Why all the stinged instruments are provided with hollow boxes?

Why is a constriction provided in a clininal thermometer?

Why are grooves provided in the soles of shoes ?

(a) With the help of a labelled diagram, explain the construction and working of a solar cooker. (b) Why is the solar cooker box painted black from inside ? (c ) Why is the solar cooker box covered with a glass sheet ?

Why are cooking utensils provided with handles made of plastic (or wood) ?