The energy flux of sunlight reaching the surface of the earth is `1.388 xx 10^3 Wm^-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 .

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 an average , arrive at a target irradiated by this beam ? (Assume the beam to have uniform cross-section which is less than the target area)

Air is streaming past a horizontal airplane wing such that its speed is 120 metre per sec over the upper surface and 90 metre per sec at the lowers surface. If the density of air is 1.3 kg per metre^(3) and the wing is 10 metre long and has an average width of 2 metre, then the difference of the pressure on the two sides of the wing is :

Ultraviolet light of wavelength 300nn and intensity 1.0Wm^-2 falls on the surface of a photosensitive material. If one per cent of the incident photons produce photoelectrons, then the number of photoelectrons emitted per second from an area of 1.0 cm^2 of the surface is nearly

Eye of an experimenter detects the green light (lambda =5000 Å) at 5xx10^4 photons per square meter per second and ear can detect 10^-13 watt per square metre. The eye is sensitive as a power detector in comparison to the ear by a factor of

A photon of wavelength 4 xx 10^-7 m strikes on metal surface, the work function of the metal being 2.14eV. Calculate The kinetic energy of the emision.(1eV )

A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1m is 1000 time . Assume that the potential energy lost each time be lower the mass is dissipated . How much far will be use up considering the work done only when the weight is lifted up ? Far supplies 3.8 xx 10^(7) J of energy per kg wich is canverted to mechanical energy with x 20 % efficiency rate Take = 9.8 ms^(-2)

Energy from the sun is recived on earth at the rate of 2 cal per cm^(2) per min. If avergae wavelength of solar light be taken at 5500 A then how many photons are recived on the earth per cm^(2) per min ? (h =6.6 xx 10^(-34)J-s, 1cal = 4.2J)