Assume that a star, which has a surface temperature of `5 xx 10^4K`,is a black body , calculate the wave length of maximum intensity in its radiation.(b=0.0029mK]

The power radiated by a black body is P and it radiates maximum energy at wavelength, lambda_(0) . If the temperature of the black body is now changed so that it radiates maximum energy at wavelength (3)/(4)lambda_(0) , the power radiated by it becomes nP. The value of n is

A stirrer rotates in 1l of water against a damping force of 0.1 N at 360 rpm in a circle of radius 5 cm. Calculate the rise in water temperature in 1 h, neglecting heat loss due to radiation . (J k= 4.2 J cdot cal^(-1))

The upper surface of an aluminium cube of side 10 cm is displaced by 0.03 cm with respect to its firmly held lower surface by a tangential force of 7.5 times 10^10 dyn . Calculate the modulus of rigidity of aluminium.

Due to rise in temperature of a brass rod by 100^(@)C , its length increases by 0.5 cm. What was the initial length of the rod? alpha for brass =19 times 10^(-6@)C^(-1) .