The threshold frequency for a photosensitive metal is 3.3

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The threshold frequency for a photosensitive metal is 3.3 × 10¹⁴ Hz. If light of frequency 8.2 × 10¹⁴ Hz is incident on this metal, the cut-off voltage for the photoelectric emission is nearly

1. 2 V
2. 3 V
3. 5 V
4. 1 V

Correct Option: A

K.E. = hν – hν_th = eV₀ (V₀ = cut off voltage)

⇒ V₀ =	h	(8.2 × 10¹⁴ - 3.3× 10¹⁴)
	e

=	6.6 × 10^-34 × 4.9 × 10¹⁴	≈ 2V.
	1.6 × 10^-19