The stopping potential for electrons emitted from a photosensitiv… - Vidyadip

MCQ

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 ....... $nm.$

A
$329$
B
$309$
✓
$382$
D
$400$

✓

Answer

Correct option: C.

$382$

c
$\frac{ hc }{\lambda}=\phi+ eV _{ s }$

$\frac{1240}{491}=\phi+0.71$

$\frac{1240}{\lambda}=\phi+1.43 $

$\therefore \lambda=382\, nm$

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