The sun radiates electromagnetic energy at the rate of `3.9xx10^(26)W`. Its radius is `6.96xx10^(8)m`. The intensity of sun light at the solar surface will be (in `W//m^(2)`)

Sun radiates energy at the rate of 3.6xx10^(26)J//s . The rate of decrease in mass of sun is (Kgs^(1)) .

The sun delivers 10^(3) W//m^(2) of electromagnetic flux is incident on a roof of dimension 8m xx 20m is 1.6 xx 10^(5) W, the radiation force on the roof will be-

If each square metre, of sun's surface radiates energy at the rate of 6.3xx10^(7) jm^(-2) s^(-1) and the Stefan's constant is 5.669xx10^(-8) Wm^(-2) K^(-4) calculate the temperature of the sun's surface, assuming Stefan's law applies to the sun's radiation.

When the centre of earth is at a distance of 1.5 xx 10^(11)m from the centre of sun, the intensity of solar radiation reaching at the earth's surface is 1.26kW//m^(2) . There is a spherical cloud of cosmic dust, containing iron particles. The melting point for iron particles in the cloud is 2000 K. Find the distance of iron particles from the centre of sun at which the iron particle starts melting. (Assume sun and cloud as a black body, sigma = 5.8 xx 10^(-8) W//m^(2)K^(4)) :

The earth receives its surface radiation from the sun at the rate of 1400 W//m^(2) . The distance of the centre of the sun from the surface of the earth is 1.5 xx 10^(11) m and the radius of the sun is 7.0 xx 10^(8) m. Treating sun as a black body, it follows from the above data that its surface temeperature is

Average distance of the sun from the earth is 1.5xx10^8 km and the average intensity of sunlight incident on the earth's surface is 1300 W . m^(-2) . Calculate the energy radiated per second from the surface of the sun.

If the distance between the sun and the earth is 1.5xx10^(11) m and velocity of light is 3xx10^(8) m//s , then the time taken by a light ray to reach the earth from the sun is