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======= ####75. Photoelectric work function of a metal is $1 e V$ . Light of wavelength $λ = 3000 \AA$ falls on it. The photo electrons come out with velocity [1991]

c3eec34ec6b1fad69db54a20ad4b2dca40c2aa54 (a) $10 m e t r e s / s e c$

(b) $10^{2}$ metres $/ s e c$

(d) $10^{6} m e t r e s / s e c$

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Answer:

Correct Answer: 75. (d)

Solution:

(d) $h v = W + \frac{1}{2} m v^{2}$ or

$\frac{h c}{λ} = W + \frac{1}{2} m v^{2}$

Here $λ = 3000 \AA = 3000 \times 10^{- 10} m$

and $W = 1 e V = 1.6 \times 10^{- 19}$ joule

$\begin{aligned} ∴ \frac{(6.6 \times 10^{- 34}) (3 \times 10^{8})}{3000 \times 10^{- 10}} \\ = (1.6 \times 10^{- 19}) + \frac{1}{2} \times (9.1 \times 10^{- 31}) v^{2} \end{aligned}$

Solving we get, $v ≅ 10^{6} m / s$

Dual Nature of Radiation and Matter - Result Question 71

75. Photoelectric work function of a metal is $1 e V$ . Light of wavelength $λ = 3000 \AA$ falls on it. The photo electrons come out with velocity [1991]

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Dual Nature of Radiation and Matter - Result Question 71

75. Photoelectric work function of a metal is 1eV. Light of wavelength λ=3000\AA falls on it. The photo electrons come out with velocity [1991]

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Answer:

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

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75. Photoelectric work function of a metal is $1 e V$ . Light of wavelength $λ = 3000 \AA$ falls on it. The photo electrons come out with velocity [1991]