Question

When a certain metal was irradiated with light of frequency 3.2 × 10¹⁶ Hz, the photoelectrons emitted had twice the kinetic energy as did photoelectrons emitted when the same metal was irradiated with light of frequency 2.0 × 10¹⁶ Hz. The light of frequency v₀ for the metal is ______ × 10¹⁵ Hz.

Options

• 10

• 8

• 6

• 0

Answer 1

When a certain metal was irradiated with light of frequency 3.2 × 10¹⁶ Hz, the photoelectrons emitted had twice the kinetic energy as did photoelectrons emitted when the same metal was irradiated with light of frequency 2.0 × 10¹⁶ Hz. The light of frequency v₀ for the metal is 8 × 10¹⁵ Hz.

Explanation:

`2/2 mv_"max"^2 = "h" (3.2 xx 10^16 - ν_0)`   ....(1)

`1/2 mv_"max"^2 = "h" (2.0 xx 10^16 - ν_0)`   ....(2)

Solving equation (1) and (2)

`2/1 = (3.2 xx 10^16 - ν_0)/(2.0 xx 10^16 - ν_0)`

`= 0.8 xx 10^16`Hz

= 8 × 10¹⁵ Hz