Two monochromatic lamps and each emit light of power

PHYSICS · Subjective · A Level · Physics · Particles and radiation · Particles and radiation

Problem

Two monochromatic lamps

A

and

B

each emit light of power

2.0\,\text{mW}

. The wavelength of light from

A

500\,\text{nm}

, while that from

B

400\,\text{nm}

. Both beams separately illuminate identical photocathodes with

100\%

quantum efficiency and work functions below

h\nu

. Calculate the ratio

I_A/I_B

of the saturation photocurrents produced by the two lamps.