A photosensitive metallic surface has work function, h v 0. If photons of energy 2hv₀ fall on this surface, the electrons come out with a maximum velocity of 4 × 106 m/s. When the photon energy is increased to 5 h v 0, then maximum velocity of photoelectrons will be (a) 2 × 107 m/s (b) 2 × 106 m/s (c) 8 × 106 m/s (d) 8 × 105 m/s

Answer: (c). 1/2mv² = E - hν₀ K₁ = 2hν₀ - hν₀ = hν₀, K₂ = 5hν₀ - hν₀ = 4hν₀ v₂ = v₁√(4) = 8×10⁶ m/s So the answer is (c) 8×10⁶ m/s.

A photosensitive metallic surface has work function, h v 0. If… | NEET 2005 (AIPMT)

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Photoelectric Effect: Einstein's Equation

A photosensitive metallic surface has work function, h $v$ 0. If photons of energy $2hv_0$ fall on this surface, the electrons come out with a maximum velocity of 4 $\times$ 106 m/s. When the photon energy is increased to 5 h $v$ 0, then maximum velocity of photoelectrons will be

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Answer: (c)

$\frac{1}{2}mv^2 = E - h\nu_0$
$K_1 = 2h\nu_0 - h\nu_0 = h\nu_0$ , $K_2 = 5h\nu_0 - h\nu_0 = 4h\nu_0$
$v_2 = v_1\sqrt{4} = 8\times10^{6}\text{ m/s}$
So the answer is (c) $8\times10^{6}$ m/s.

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