Question

The work function of potassium is 2.24 eV. The region of the elctro spectrum which liberates the electron from potassium is 

(1) 5.5 × 10^–7 to 8 × 10^–7 m

(2) 6 × 10^–7 to 7×10^–7 m 

(3) wavelengths longer than 5.52 × 10^–7 m 

(4) wavelengths shorter than 5.52 × 10^–7 m 

Answer 1

Correct option : (4) wavelengths shorter than 5.52 × 10^–7 m

Explanation :

The Einstein’s photoelectric equation is given by hv = 1/2 mv² + ω₀ 

When the electrons are just liberated v = 0 and the corresponding frequency is 

Hence wavelengths shorter than 5.52 × 10^–7 m can cause the emission of photoelectrons from potassium.