Question

Two different metal rods of the same length have their ends kept at the same temperatures and  with . If A and are their cross-sectional areas and k1 and k2 their thermal conductivities, the rate of flow of heat in the two rods will be the same if

Solution

Correct option is

 

Rate of flow is 

Since  and l are the same for the two rods, the rate of flow Q/twill be the same if the product kA is the same if the product kA is the same for the two rods, i.e. if

                       

or                      

SIMILAR QUESTIONS

Q1

300 g of water at 25oC is added to 100 g of ice at 0oC. The final temperature of the mixture is

Q2

100 g of ice at 0oC is mixed with 100 g of water 80oC. The final temperature of the mixture will be

Q3

Steam at 100oC is passed into 1.1 kg of water contained in a calorimeter of water equivalent 0.02 kg at 15oC till the temperature of the calorimeter rises to 80oC. The mass of steam condensed in kilogram is

Q4

If there are no heat losses, the heat released by the condensation of xgrams of steam at 100oC into water 100oC converts y grams of ice at 0oC into water at 100oC. The ratio y/is nearly

Q5

One mole of oxygen is heated from 0oC, at constant pressure, till its volume increases by 10%. The specific heat of oxygen, under these conditions is 0.22 cal g – 1 K – 1. The amount of heat required (in joules) is

Q6

A drilling machine of power P watts is used to drill a hole in copper block of mass M kg. If the specific heat of a copper is s J  and 40% of  the power is lost due to heating of the machine, the rise in the temperature of the block in T seconds will be (in oC)

Q7

A geyser, operating on LPG (liquefied petroleum gas) heats water flowing at the rate of 3.0 litres per minute, from 27oC to 77oC. If the heat of combustion of LPG is , how much fuel in grams is consumed per minute?

Q8

A copper block of mass 2 kg is heated to a temperature of 500oC and then placed in a large block of ice at 0oC. What is the maximum amount of ice that can melt? The specific heat of copper is 400 j  and latent heat of fusion of water is .

Q9

The dimensions of the coefficient of thermal conductivity are

Q10

Two rods A and B of different materials are welded together as shown in Fig. If their thermal conductivities are k1 and k2 , the thermal conductivity of the composite rod will be