If reflectance of a surface is `0.4` and absorptance is `0.2` what is the transmittance of the surface?

Heat energy is incident on the surface at the rate of 1000 J/min. If coefficient of absorption is 0.8 and coefficient of reflection is 0.1 then heat energy transmitted by the surface in 5 minute is

A point charge of 2.0 muC is at center of a cublic Gaussian surface 9.0 cm on edge. What is the net electric flux through the surface?

Light with an energy flux of 18 W cm^(-2) falls on a non-reflecting surface at normal incidence. If the surface at normal incidence. If the surface has an area of 20 cm^(2) , find the average force exerted on the surface during a span of 30 min.

Figure shows a transparent hemisphere of radius 3.0 cm made of a material of refractive index 2.0. (a) A narrow beam of parallel rays is incident on the hemisphere as shown in the figure. Are the rays totally reflected at the plane surface ? (b) Find the image formed by the refraction at the first surface. (c) Find the image formed by the reflection or by the refraction at the plane surface. (d) Trace qualitatively the final rays as they come out of the hemisphere.

A plane wavefront incident on a reflecting surface at and angle of 30^(@) with vertical. Find the angle (acute) of reflected wave with vertical.

The maximum kinetic energy of photoelectrons emitted from a metal surface increses from 0.4 eV to 1.2 eV when the frequency of the incident radiation is increased by 40% . What is the work function (in eV) of the metal surface?

Angle of a prism is 30^(@) and its refractive index is sqrt(2) and one of the surface is silvered. At what angle of incidence, a ray should be incident on one surface so that after reflection from the silvered surface, it retraces its path ?

A point source of light is placed at a distance h below the surface of a large deep lake.What is the percentage of light energy that escapes directly form the water surface if mu of the water= 4//3 ?(neglet partial reflection)

A point object is kept at a distance of 2 m from a parabolic reflecting surface y^(2) = 2x . An equiconvex lens is kept at a distance of 1.80 m from the parabolic surface. The focal length of the lens is 20 cm . Find the position from origin of the image in cm, after reflection from the surface.

Calculate the power of an incandescent lamp whose filament has a surface area of 0.19 cm^(2) and is at a temperature of 3645K. Emmisivity of the surface is 0.4, sigma = 5.7xx10^(-8)Wm^(-2)K^(-4) ?