Previous Years GATE Questions on Conduction 2001-2005

Solved GATE Questions on Conduction

Question 1. In descending order of magnitude, the thermal conductivity of (a) pure iron, (b) liquid water, (c) saturated water, and (d) pure aluminium can be arranged as

(A) a b c d

(B) b c a d

(C) d a b c

(D) d c b a

GATE-ME-2001

Hint

Question 2. Lumped heat transfer analysis of a solid object suddenly exposed to a fluid medium at a different temperature is valid when

(A) Biot number0.1

(B) Biot number 0.1

(C) Fourier number 0.1

(D) Fourier number0.1

GATE-ME-2001

Hint

Question 3. The value of Biot number is very small (less than 0.01) when

(A) The convective resistance of the fluid is negligible

(B) The conductive resistance of the fluid is negligible

(C) The conductive resistance of the solid is negligible.

(D) None of these

GATE-ME-2002

Hint

Question 4. A 2 kW, 40 litre water heater is switched on for 20 minutes. The heat capacity  for water is 4.2 kJ/kg K. Assuming all the electrical energy has gone into heating the water, increase of the water temperature in degree centigrade is

(A) 2.7

(B) 4.0

(C) 14.3

(D) 25.25

GATE-ME-2003

Hint

Question 5. A spherical thermocouple junction of diameter 0.706 mm is to be used for the measurement of temperature of a gas stream. The convective heat transfer co-efficient on the bead surface is 400 W/. Thermophysical properties of thermocouple material are and . If the thermocouple initially at 30 is placed in a hot stream of 300, then time taken by the bead to reach 298, is

(A) 2.35 s

(B) 4.9 s

(C) 14.7 s

(D) 29.4 s

GATE-ME-2004

Hint

Question 6. A stainless steel tube () of 2 cm ID and 5 cm OD is insulated with 3 cm thick asbestos (). The temperature difference between the innermost and outermost surfaces is 600 , the heat transfer rate per unit length is

(A) 0.94 W/m

(B) 9.44W/m

C) 944.72 W/m

(D) 9447.21 W/m

GATE-ME-2004

Hint

Question 7. One dimensional unsteady state heat transfer equation for a sphere with heat generation at the rate of  can be written as

(A) 

(B) 

(C) 

(D) 

GATE-ME-2004

Hint

Question 8. A small copper ball of 5 mm diameter at 500 K is dropped into an oil bath whose temperature is 300 K. the thermal conductivity of copper is 400 W/m.K, its density 9000 kg/ and its specific heat 385 J/kg K. if the heat transfer coefficient is 250 W/ and lumped analysis is assumed top be valid, the rate of fall of the temperature of the ball at the beginning will be, in K/s

(A) 8.7

(B) 13.9

(C) 17.3

(D) 27.7

GATE-ME-2005

Hint

Question 9. Heat flows through a composite slab, as shown below. The depth of the slab is 1m. the k values are in W/mK. The overall thermal resistance in K/W is

(A) 17.2

(B) 21.9

(C) 28.6

(D) 39.2

GATE-ME-2005

Hint

Question 10. In case of one dimensional heat conduction in a medium with constant properties, T is the temperature at position x, at time t. Then  is proportional to

(A) 

(B) 

(C) 

(D) 

GATE-ME-2005

Hint

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