A 25 watt emits monochromatic yellow light of wavelength of `0.57 mu m`. Calculate the rate of emmision of quanta per second.

A modern 200 W sodium street lamp emits yellow light of wavelength 0.6 mum . Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is

Yellow light emitted from a sodium lamp has a wavelength (lambda) of 580 nm. Calculate the frequency (v) and wave number (barv) of the yellow light.

A photoelectric surface is illuminated successively by monochromatic light of wavelength lambda and (lambda)/(2) . If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times than in the first case , the work function of the surface of the material is ( h = Plank's constant , c = speed of light )

A coil of dimensions 30 cm xx 20 cm is kept such that its plane is at right angles to the direction of uniform magnetic field of value 0.08 Wb/m^2 . Calculate the e.m.f . induced in the coil, If the value of field is reduced to 25 percent of the original value in 0.6 second.

In a biprism experiment , the slit is illuminated by a light of wavelength of 5000 overset (@)(A) . The distance between the slit and eyepiece is 1 m . If the distance between the two virtual sources is 0.25 cm , then distance between fifth bright band on one side and the sixth dark band on the other sideof the central bright band will be

The threshold wavelength for silver is 3800overset@ A . Calculate maximum kinetic energy in eV of photoelectrons emitted when ultraviolet light of wavelength 2600overset@ A falls on it. Also calculate stopping potential ( 1 eV = 1.6 xx 10^-19 J , Planck's constant = h = 6.63 xx 10^-34 Js , speed of light in vacuum = 3 xx 10^8 m//s ).

When holes are dug into the Earth, it is found that for a depth of every 30 m, the temperature rises by 1^@C . If the coefficient of conductivity of Earth's crust is 0.8 watt//m^@k , calculate the amount of heat flowing through an area of 1 sq. metre on surface of earth, per minute

The difference in temperature between two sides of a glass plate 0.3 mm thick is 25^@C . If the area of one side surface is 10 m^2 , calculate the heat conducted per second through the plate. The thermal conductivity of glass is 0.84 J//s m K.