Question

Ultraviolet light of wavelength 300 nm and intensity 1.0 watt/m² falls on the surface of a photosensitive material. If 1% of the incident photons produce photoelectrons, then the number of photoelectrons emitted from an area of 1.0 cm² of the surface is nearly –

• A. 9.61 × 10¹⁴ per sec
• B. 4.12 × 10¹³ per sec
• C. 1.51 × 10¹² per sec
• D. 2.13 × 10¹¹ per sec

Answer 1

Answer: (C)

1.51 × 10¹² per sec

Answer 2

n_e = n_c (n_ph)

= $\frac { 1 } { 100 }$ [5 × 10²⁴ × 1 × 10^–4 × 300 × 10^–9]

= 15 × 10¹¹ =1.5 × 10¹²/sec