Calculate the number of photon emitte per second by a 10 watt Na lamp. Assume 90% of consumed energy converted into light. Wave length of Na lamp 530 nm.

Calculate the number of photons emitted per second by a 10 W sodium vapour lamp. Assume that 60% of the consumed energy is converted into light. Wavelength of sodium light = 590 nm.

Calculate the number of photons emitted in 10 hours by a 60 W sodium lamp ( lambda = 6000Å )

What do you mean by photo electric effect? Calculate the energy of one mole of photons of radiations having wave length 200 nm.

A 200 watt bulb emits mono chromatic light of wave lenth 400 nm. Calculate the number of photons emitted per sec by the bulb.

A person trying to lose weight (dieter) lifts a 10 kg mass, one , thousand times, to a height of 0.5 m each time. Assume that the potential energy lost each time she lowers the mass is dissipated, (a) How much work does she do against the gravitational force? (b) Fat supplies 3.8 xx 10^7 J of energy per kilogram which is converted to mechanical energy with a 20% efficiency rate. How much fat will the dieter use up?

A 100 watt sodium lamp is emitting light of W.L 5890Å . Calculate the rate of emission of photons.