Discussion Forum



1)

Assertion (A) Si and GaAs  are the preferred materials for solar cells

Reason (R)  Both these materials  have energy  band gaps much below the energy level corresponding to the maximum solar irradiance in the solar spectrum

The correct answer is


A) (A) is correct but (R) is incorrect

B) Both (A) and (R) are correct and (R0 is the correct explanation of (A)

C) Both (A) and (R) are correct. but (R0 is not the correct explanation of (A)

D) Both (A) and (R) are incorrect

Answer:

Option A

Explanation:

Key idea: The energy band gap  of Si is 1.14 eV and GaAs is 1.42 eV

 Both Si and GaSa are used to make solar cells. In visible spectrum , energy varies from about 3eV on the violet side to 1.5 eV  on red side, so visible  light can make solar energy

But radiowaves, microwaves and infrared waves have less photon energy than the bandgap of Si and GaAs.

Hence, the assertion is correct but the reason is wrong. Therefore , the correct option is(a)