Light source having wavelength 331 nm is used to generate photo-electrons whose stopping potential is 0.2 V

Question

Light source having wavelength 331 nm is used to generate photo-electrons whose stopping potential is 0.2 V. The work function of the used metal in the experiment is $α \times 10^{- 19} J$ . The value of $α$ is _______. [2026]

( $h = 6.62 \times 10^{- 34} Js, e = 1.6 \times 10^{- 19} C$ and $c = 3 \times 10^{8} m/s$ )

Smart Achievers · Accepted Answer

(3)

$λ = 331 nm$

$α$

$e V_{s} = \frac{h c}{λ} - ϕ$

$ϕ = \frac{1240}{331} eV - 0.2 eV = 3.546 eV$

$\Rightarrow ϕ = 3.546 \times 1.6 \times 10^{- 19} J = 5.67 \times 10^{- 19} J$

Solution

1 3.68

2 4.68

3 5.68

4 2.68

Ans.
(3)

$λ = 331 nm$

$V_{s} = 0.2 V$

$e V_{s} = \frac{h c}{λ} - ϕ$

$ϕ = \frac{1240}{331} eV - 0.2 eV = 3.546 eV$

$\Rightarrow ϕ = 3.546 \times 1.6 \times 10^{- 19} J = 5.67 \times 10^{- 19} J$

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