Thermal Propert...

Three rods of identical area of cross-section and made from the same metal from the sides of an isosceles triangle ABC, right angled at B. The points A and B are maintained at temperatures T and √2T respectively. In the steady state the temperature of the point C is T_C. Assuming that only heat conduction takes place, T_C/T is equal to

The only possibility of heat flow in a thermos flask is through its cork which is 75 cm² in area and 5 cm thick. Its thermal conductivity is 0.0075 cal/cm sec^oC. The outside temperature is 40^oC and latent heat of ice is 80 cal g^–1. Time taken by 500 g of ice at 0^oC in the flask to melt into water at 0^oC is

A sphere, a cube and a thin circular plate, all made of the same material and having the same mass are initially heated to a temperature of 1000^oC. Which one of these will cool first

Two identical conductance rods are first connected identically to two vessels, one containing water at 100^oC and the other containing ice at 0^oC. In he second case, the rods are joined end to end and connected to the same vessels. Let q₁ and q₂ g/s be the rate of melting of ice in two cases respectively. The ratio of q₁/q₂ is

A black body is at a temperature of 2880 K. The energy of radiation emitted by this object with wavelength between 499 nm and 500 nm is U₁, between 999 nm and 1000 nm is U₂ and between 1499 nm and 1500 nm is U₃. The Wien\'s constant b = 2.88 × 10⁶ nmK. Then,

A black metal foil is warmed by radiation from a small sphere at temperature T and at a distance d. It is found that the power received by the foil is \'P\'. If both the temperature and the distance are doubled, the power received by the foil will be

Three rods of same dimensions are arranged as shown in figure. They have thermal conductivities K₁, K₂ and K₃. The points P and Q are maintained at different temperatures for the heat to flow at the same rate along PRQ and PQ then which of the following options is correct?

Two metallic spheres S₁ and S₂ are made of the same material and have identical surface finish. The mass of S₂ is three times that of S₁. Both the spheres are heated to the same high temperature and placed in the same room having lower temperature but are thermally insulated from each other. The ration of the initial rate of cooling of S₁ to that of S₂

Three discs A, B and C having radii 2 m, 4 m and 6 m respectively are coated with carbon black on their other surfaces. The wavelengths corresponding to maximum intensity are 300 nm, 400 nm and 500 nm respectively. The power radiated by them are Q_a, Q_b and Q_c resectively

The total energy radiated from a black body source is collected for one minute and is used to heat a quantity of water. The temperature of water id found to increase form 20^oC to 20.5^oC. If the absolute temperature of the black body is doubled and the experiment is repeated with the same quantity of water at 20^oC, the temperature of water will be