Question

19. Photons of 5.5 eV energy falls on the surface of
the metal emitting photoelectrons of
maximum kinetic energy 4.0 eV. The stopping
voltage required for these electrons are
a) 5.5 V b) 1.5 V c) 9.5 V d) 4.0 V
20. If an electron oscillates at a frequency of 1 GHz
it gives
a) X-rays
b) Mirowaves
c) Infrared rays d) None of these
​

Answer 1

Answer:4 v

Explanation:kinetic energy= even and stopping voltage= v. So we can write after removing v from ev then it will give u stopping voltage. Because stopping voltage means that maximum voltage required to stop the particle having Max kinetic energy.

Answer 2

Stopping potential is 4 volt

None of the above

Explanation:

(19) Energy of photon is 5.5 eV and the maximum kinetic energy of the photo electrons is 4 eV.

The maximum kinetic energy is given by :

$E_{max}=eV_o$

$V_o$ is stopping potential

$4eV=eV_o\\\\V_o=4\ V$

So, the stopping  voltage required for these electrons is 4 volt.

• These all three waves are of very high frequency such as frequency of microwave is 300 ghz,infrared 430 thz so this frequency can't produce these higher waves . The correct option is (d).

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