The stopping potential for electrons emitted from a photosensitive surface illuminated by light of wavelength 491 nm is 0.710 V. When the incident wavelength is changed to a new value, the stopping potential is 1.43 V. The new wavelength is :

Question

The stopping potential for electrons emitted from a photosensitive surface illuminated by light of wavelength 491 nm is 0.710 V. When the incident wavelength is changed to a new value, the stopping potential is 1.43 V. The new wavelength is : (A) 329 nm (B) 309 nm (C) 382 nm (D) 400 nm

Tardigrade Admin · Accepted Answer

( hc /λ)=φ+ eV s (1240/491)=φ+0.71 ldots(1) (1240/λ)=φ+1.43 ldots (2) ∴ λ=382 nm

Q. The stopping potential for electrons emitted from a photosensitive surface illuminated by light of wavelength $491 nm$ is $0.710 V$ . When the incident wavelength is changed to a new value, the stopping potential is $1.43 V$ . The new wavelength is :

$329 nm$

$309 nm$

$382 nm$

$400 nm$

$\frac{h c}{λ} = ϕ + e V_{s}$
$\frac{1240}{491} = ϕ + 0.71 \dots$ (1)
$\frac{1240}{λ} = ϕ + 1.43 \dots$ (2)
$∴ λ = 382 nm$

Q. The stopping potential for electrons emitted from a photosensitive surface illuminated by light of wavelength 491nm is 0.710V. When the incident wavelength is changed to a new value, the stopping potential is 1.43V. The new wavelength is :

329nm

309nm

382nm

400nm