Electronic Devices and Circuits - Engineering

Q1:

Photo electric emission can occur only if

A wave length of incident radiation is equal to threshold value

B wave length of incident radiation is less than threshold value

C frequency of incident radiation is less than threshold frequency

D none of the above

ANS:B - wave length of incident radiation is less than threshold value

The frequency of incident radiation has to be more than threshold value. Wavelength is inversely proportional to frequency. Therefore wavelength of incident radiation must be less than threshold value.