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Stopping Potential

The work func...

Question

The work function of Potassium is $2.0 e V$ . When it is illuminated by light of wavelength $3300$ $A^{o}$ , photoelectrons are emitted. The stopping potential of photoelectrons is :

[ $h = 6.6 \times 10^{- 34} J s, 1 e V = 1.6 \times 10^{- 19} J$ , Velocity of light, $c = 3 \times 10^{8} m s^{- 1}$ ]

A

0.75 V

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B

1.75 V

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C

2.5 V

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D

3.75 V

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Solution

The correct option is B $1.75 V$
$S t o p p i n g p o t e n t i a l = (\frac{h c}{λ} - ϕ) / e$
$= (\frac{1240}{330} - 2) / e (h c = 1240 e V - n m)$
$= (3.75 - 2) / e$
$= 1.75 e V / e$
$= 1.75 V$

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Similar questions

Q. The work function of a metal is

2 e V

. If a radiation of wavelength

3000

˚ A

is incident on it, the maximum kinetic energy of the emitted photoelectrons is :
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h = 6.6 \times 10^{- 34} J s

; Velocity of light

c = 3 \times 10^{8} m / s; 1 e V = 1.6 \times 10^{- 19} J

Q. The work function of a metal is

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What is the work function of the metal if the light of wavelength

4000 ˚ A

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6 \times 10^{5} m s^{- 1}

[Given: Mass of electron

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Velocity of light

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Planck's constant

= 6.626 \times 10^{- 34} J s

Charge of electron

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Q. What is the work function of the metal if a light of wavelength

4000 \circ A

generates photoelectrons of velocity

6 \times 10^{5} {ms}^{- 1}

from it?
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