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

(a) 0.65 eV

(b) 1.0 eV

(c) 1.3 eV

(d) 1.5 eV

Answer 1

The correct option is (b) 1.0 eV.

Explanation:

According to Einstein's photoelectric equation, 

The kinetic energy of emitted photoelectrons is

K = hv - ϕ_o

where hv is the energy of incident radiation and ϕ_o is work function of the metal. 

As per question

Comments

E is increased by 20% ... But how did 1.2 come out

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Let Initial energy was E.

Then after increasing it by 20% it becomes 1.2 E .