Question

pointsource of light placed at distanced from the photo cell if the distance becomes d/3 numberofelectronemittedper second
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Answer 1

Answer:

it is very hard question

Answer 2

When the distance of light source becomes d/3, the number of electrons emitted per second -

• Intensity = E/At
• Where, E = total energy of source
• A = area of illuminated surface
• t = time
• Therefore, I = E/4πr²t
• I1/I2 = E / 4πr1²t  ×  4πr2²t / E
• I1/I2 = r2²/r1²
• I2/I1 = r1²/r2²
• Therefore, Intensity of light or the number of electrons emitted per second is inversely proportional to square of distance
• I  ∝  1 / d²
• Hence, when the distance is reduced to d/3, the number of electrons emitted increase by 9 times.