Question

In a solar water heater, a copper pipe with its outer surface painted in black is fixed in the form of a coil in a box.
(A) The only purpose of bending copper pipes is to increase the capacity of water storage.
(B) bending the copper pipe as a coil helps to increase the surface area for heating.
(C) Both (1) and (2)) are true.
(D) Both (1) and (2)) are false.

Answer 1

Hint
A solar water heater is a gadget that encapsulates sunlight to heat water. It can be an inexpensive way to produce hot water for your family. A solar heater not only empowers significant energy retrenchment as solar power is free in contradiction to natural gas or fuel oil.

Complete step by step answer
In solar water heaters, a pipe of copper with its external surface painted black is attached in the form of a coil in a box which is painted black from inside. The external surface of the copper tube and interior walls of the box are pointed black to increase absorption of heat to give out high temperature. Like in the solar cooker, the box of solar water heater is also shielded with a glass sheet to capture the heat inside the box. One end of the copper pipe is joined to the bottom of the water storage tank, while the other end is joined near its middle.
The cool water that is present in the water cache tank enters the copper pipe joined to it at the bottom and goes slowly through the coil of copper placed in the box. When the cool water goes through the coil of copper it absorbs solar heat and gets heated. The hot water comes out from the other end of the copper pipe and enters the upper part of the water catch tank. This hot water is restored by the cool water contained in the tank.
The outer surface of the copper tube and inner walls are painted black to increase the absorption of heat to produce high temperatures. Moreover, when it is fixed in the form of a coil in a box the surface area available for absorption is increased.
Therefore, bending the copper pipe as a coil helps to increase the surface area for heating.
Hence the option (B) bending the copper pipe as a coil helps to increase the surface area for heating is the correct answer.

Note
The copper pipe of solar water heater is painted black in colour from outside so that maximum amount of heat rays of the sun is absorbed and the coherence of solar water heater is increased.