A photosensitive metallic surface has work function, hν0.

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A photosensitive metallic surface has work function, hν₀. If photons of energy 2 hν₀ 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 hν₀, then maximum velocity of photo electrons will be

1. 2 × 10⁷ m/s
2. 2 × 10⁶ m/s
3. 8 × 10⁶ m/s
4. 8 × 10⁵ m/s

Correct Option: C

We know that

hv - φ = K_max =	1	mv²_max
	2

According to question

	5hv₀ - hv₀	=	v₂²
	2hv₀ - hv₀		v₁²

v₂ = 2v₁ = 2 × 4× 10⁶ = 8 × 10⁶ m/s.