If radiation is totally absorbed and energy incident on surface in time t be U then write equation of momentum imparted to surface.

Radiation of energy E is incident on complete reflecting surface.Momentum imparted to surface will be……

Work function of photosensitive surface is phi .When photon of 3phi energy is incident on surface electron with maximum speed of 6xx10^(6)m//s is emitted from the surface .If energy of photon is changed to 9phi ,maximum speed of photoelectron will be.......

When a jet of liquid strikes a fixed or moving surface, it exerts thrust on it due to rate of change of momentum. F=(rhoAV_(0))V_(0)-(rhoAV_(0))V_(0)costheta=rhoAV_(0)^(2)[1-costheta] If surface is free and starts moving due to thrust of the liquid, then at any instant, the above equation gets modified based on relative change of momentum with respect to surface. Let, at any instant, the velocity of surface be u . Then the above equation becomes F=rhoA(V_(0)-u)^(2)[1-costheta] Based on the above concept, as shown in the following figure, if the cart is frictionless and free to move in the horizontal direction, then answer the following. Given that cross sectional area of jet =2xx10^(-4)m^(2) velocity of jet V_(0)=10m//s density of liquid =1000kg//m^(3) ,mass of cart M=10 kg . Initially ( l=0 ) the force on the cart is equal to

According to Stefan's law of radiation, a black body radiates energy sigmaT^(4) from its unit surface area every second where T is the surface temperature of the black body and sigma=5.67xx10^(-8)W//m^(2)K^(4) is known as Stefan's constant. A nuclear weapon may be thought of as a ball of radius 0.5 m. When detonated, it reaches temperature of 10^(6) K and can be treated as a black body. If all this energy U is in the form of radiation, corresponding momentum is p=U/c . How much momentum per unit time does it impart on unit area at a distance of 1 km ?

Frequency of radiation incident on metal surface is called threshold frequency.

A big drop is formed by coalescing 1000 small droplets of water. What will be the change in surface energy What will be the ratio between the total surface energy of the droplets and the surface energy of the big drop?

When the energy of the incident radiation is increased by 20% ,the kinetic a metal surface increased from 0.5 eV to 0.8 eV.The work function of the metal is …..

According to Stefan's law of radiation, a black body radiates energy sigmaT^(4) from its unit surface area every second where T is the surface temperature of the black body and sigma=5.67xx10^(-8)W//m^(2)K^(4) is known as Stefan's constant. A nuclear weapon may be thought of as a ball of radius 0.5 m. When detonated, it reaches temperature of 10^(6) K and can be treated as a black body. Estimate the power it radiates.

A point source is emitting 0.2 W of ultravio- let radiation at a wavelength of lambda = 2537 Å . This source is placed at a distance of 1.0 m from the cathode of a photoelectric cell. The cathode is made of potassium (Work function = 2.22 eV ) and has a surface area of 4 cm^(2) . (a) According to classical theory, what time of exposure to the radiation shall be required for a potassium atom to accumulate sufficient energy to eject a photoelectron. Assume that radius of each potassium atom is 2 Å and it absorbs all energy incident on it. (b) Photon flux is defined as number of light photons reaching the cathode in unit time. Calculate the photon flux. (c) Photo efficiency is defined as probability of a photon being successful in knocking out an electron from the metal surface. Calculate the saturation photocurrent in the cell assuming a photo efficiency of 0.1. (d) Find the cut – off potential difference for the cell.

A radiation of energy 'E' falls normally on a perfectly reflecting surface. The momentum transferred to the surface is (c = Velocity of light) :