Heat Transfer Questions

Two rectangular blocks, having identical dimensions, can be arranged either in configuration I or in configuration II as shown in the figure. One of the blocks has thermal conductivity k and the other...

The condition under which a microwave oven heats up a food item containing water molecules most efficiently is :-

Three rods of copper, brass and steel are welded together to form a Y-shaped structure. Area of crossseciton of each rod = 4 cm2. End of copper rod is maintained at 100oC whereas ends of brass and ste...

Parallel rays of light of intensity I = 912 Wm-2 are incident on a spherical black body kept in surroundings of temperature 300 K. Take Stefan-Boltzmann constant σ = 5.7 × 10-8 Wm-2K-4 and ...

Steam at 100oC is passed into 20 g of water at 10oC. When water acquires a temperature of 80oC, the mass of water present will be: [Take specific heat of water = 1 cal g-1 oC-1 and latent heat of stea...

Certain quantity of water cools from 70oC to 60oC inthe first 5 minutes and to 54oC in the next 5 minutes. The temperature of the surroundings is...

An irregular rod of same uniform material as shown in figure is conducting heat at a steady rate. The temperature gradient at various sections versus area of cross section graph will be...

A radiation of energy ′E′ falls normally on a perfectly reflecting surface. The momentum transferred to the surface is (C = Velocity of light) :-

A black body is at a temperature of 5760 K. The energy of radiation emitted by the body at wavelength 250nm is U1, at wavelength 500 nm is U2 and that at 1000 nm is U3. Wien’s constant, b = 2.88...

The figure below shows the variation of specific heat capacity (C) of a solid as a function of temperature (T). The temperature is increased continuously from 0 to 500 K at a constant rate. Ignoring a...

Heater of an electric kettle is made of a wire of length L and diameter d. It takes 4 minutes to raise the temperature of 0.5 kg water by 40 K. This heater is replaced by a new heater having two wires...

If a piece of metal is heated to temperature θ and then allowed to cool in a room which is at temperature θ0 the graph between the temperature T of the metal and time t will be closed to :...

A liquid in a beaker has temperature θ(t) at timet and θ0 is temperature of surroundings, thenaccording to Newton′s law of cooling thecorrect graph between loge (θ - θ0) and ...

A slab of stone of area 0.36 m2 and thickness 0.1 m is exposed on the lower surface to steam at100oC. A block of ice at 0oC rests on the upper surface of the slab. In one hour 4.8 kg of ice is melted....

If the radius of a star is R and it acts as a black body, what would be the temperature of the star, inwhich the rate of energy production is Q? (σstands for Stefan′s constant)...

Three very large plates of same area are kept parallel and close to each other. They are considered as idealblack surfaces and have very high thermal conductivity. The first and third plates are maint...

The rate of increase of thermo e.m.f with temperature at the natural temperature of a thermocouple

A cylindrical metalic rod in thermal contact with two reservoirs of heat at its ends conducts an amount of heat Q, in time t. The metallic rod is melted and the material is formed into rod of half the...

The total radiant energy per unit area, normal to the direction of incidence, received at a distance R from the the centre of a star of radius r, whose outer surface radiated as a black body at a temp...

A long metallic bar is carrying heat from one of its ends to the other end under steady-state. The variation of temperature θ along the length x of the bar from its hot end is best described by w...