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PHOTOELECTRIC EFFECT CLASS 12 SOLUTIONS NOTES PDF

CLASS 12

NCERT

CHAPTER 11 DUAL NATURE OF RADIATION AND MATTER SOLUTIONS

PHYSICS

PHOTOELECTRIC EFFECT

The energy flux of sunlight reaching the surface of the earth is 1.388 × 10^3 W/m^2. How many photons (nearly) per square metre are incident on the Earth per second? Assume that the photons in the sunlight have an average wavelength of 550 nm.

The number of photons emitted per second by a Medium wave transmitter of 10 kW power, emitting radiowaves of wavelength 500 m. (b) The number of photons entering the pupil of our eye per second corresponding to the minimum intensity of white light that humans can perceive (10^10 W m^–2). Take the area of the pupil to be about 0.4 cm^2 , and the average frequency of white light to be about 6 × 10^14 Hz.

A 100W sodium lamp radiates energy uniformly in all directions. The lamp is located at the centre of a large sphere that absorbs all the sodium light which is incident on it. The wavelength of the sodium light is 589 nm. (a) What is the energy per photon associated with the sodium light? (b) At what rate are the photons delivered to the sphere ?