A 1.5 kW (kilo-watt) laser beam of wavelength 6400 Å is used to levitate a thin aluminium disk of same area as the cross section of the beam. The laser light is reflected by the aluminium disk without any absorption. The mass of the foil is close to -

A 1.5 kW (kilo-watt) laser beam of wavelength 6400 Å is used to levitate a thin aluminium disc of same area as the cross section of the beam. The laser light is reflected by the aluminium disc without any absorption. The mass of the foil is close to

A beam of light of wavelength 6400 Å is incident normally on a parallel glass plate of 5cm thick and R.I. 1.6. The beam takes the same time to travel from source to incident surface and through the glass plate. The distance of source from incident surface is

A radiation of wavelength 200nm is propagating in the form of a parallel surface. The power of the beam is 5mW and its cross-sectional area is 1.0 mm^(2) . Find the pressure exerted by radiation on the metallic surface if the radiation is completely reflected.

A radiation of wavelength 200nm is propagating in the form of a parallel surface. The power of the beam is 5mW and its cross-sectional area is 1.0 mm^(2) . Find the pressure exerted by radiation on the metallic surface if the radiation is completely reflected.

A parallel beam of sodium light of wavelength 6000 Å is incident on a thin glass plate of mu=1.5 , such that the angle of refraction in the plate is 60^(@) . The smallest thickness of the plate which will make it appear dark by reflected light is

A parallel beam of sodium light of wavelength 6000 Å is incident on a thin glass plate of mu=1.5 , such that the angle of refraction in the plate is 60^(@) . The smallest thickness of the plate which will make it appear dark by reflected light is

Monochromatic light of wavelength 632.8 nm is produced by a helium-neon laser. The power emitted is 9.42 mW. How many photons per second, on the average, arrive at a target irradiated by this beam? (Assume the beam to have uniform cross-section which is less than the taget area).