Question
When the energy of the incident radiation is increased by 20%, the kinetic energy of the photoelectrons emitted from a metal surface increased from 0.5 eV to 0.8 eV. The work function of the metal is,
-
0.65 eV
-
1.0 eV
-
1.3 eV
-
1.5 eV
Solution
B.
1.0 eV
For photoelectric equation,
(KE)min = 
For the first condition,
0.5 = E - 
... (i)
For the second condition,
... (ii)
From equations (i) and (ii),
and 
-0.3 = -0.2 E
E = 
From expression (i),
0.5 = 1.5 - 
