Find the pressure of saturated tungsten vapour at a temperature `T = 2000 K` if a tungsten filament is known to lose a mass `mu = 1.2-10^-13 g//(s. cm^2)` from a unit area per unit time when evaporating into high vacuum at this temperature.

Find the emissive power from "0.3 cm"^(2) surface of filament of bulb of tungsten at 3000 K temperature. Take e=0.4 for tungsten bulb.

Two bodies A and B at temperatures T_(1)K and T_(2)K respectively have the same dimensions. Their emissivities are in the ratio of 1 : 3 . If they radiate the same amount of heat per unit area per unit time, then the relation between their temperatures is given by

A comon flashlight bulb is rated 0.30A and 2.7V (the values of the current and voltage under operating conditions.) If the resistance of the tungsten bulb filament at room temperature 20^(@)C is 1.0Omega and its temperature coefficient of resistivity is 4.0 xx 10^(-3)C^(-1) , then find the temperature in centigrade of the filament when the bulb is on. (Consider the variationi of resistance to be linear with temperature.)

A black body at a temperature of 227 ^@C radiates heat at a rate of 5 cal//cm^2s . At a temperature of 727 ^@C , the rate of heat radiated per unit area will be

A bulb made of tungsten filament of surfece area 0.5 cm^2 is heated to a temperature 3000K when operated at 220V.The emissivity of the filament is in=0.35 and take sigma=5.7xx10^-8 mks units. Then the power of the bulb is,

A black body at temperature 227^(@)C radiates heat at the rate of 5 cal/ cm^(2) , at a temperature of 27^(@)C , the rate of heat radiated per unit area per unit time in cal/ cm^(2) s, is

The operating temperature of an in candescent bulb (with tungsten filament) of power 60 W is 3000 K. If the surface area of the filament be 25 mm^2 , find its emissivity e.