MODES OF HEAT TRANSFER OBJECTIVE QUESTIONS (GATE, IES, IAS)PREVIOUS...
1. Modes of Heat Transfer
O
BJECTIVEQ
UESTIONS(GATE, IES, IAS)
Previous 20-Years GATE Questions Fourier's Law of Heat ConductionGATE-1. For a given heat flow and for the same thickness, the temperature drop
across the material will be maximum for
[GATE-1996]
(a) Copper
(b) Steel
(c) Glass-wool
(d) Refractory brick
GATE-2. Steady two-dimensional heat conduction takes place in the body shown
in the figure below. The normal temperature gradients over surfaces P
∂
and Q can be considered to be uniform. The temperature gradient
T
x
at surface Q is equal to 10 k/m.
Surfaces
P and Q are maintained at
constant temperatures as shown in the figure, while the remaining part
of the boundary is insulated. The body has a constant thermal
∂
∂
conductivity of 0.1 W/m.K. The values of
T
and
T
x
y
∂
∂
at surface P are:
∂
K
m
T
=
0
/
T
=
(a)
20
K
/
m
,
y
x
T
=
10
/
(b)
0
K
/
m
,
(c)
10
K
/
m
,
T
=
20
/
(d)
0
K
/
m
,
[GATE-2008]
GATE-3. A steel ball of mass 1kg and specific heat 0.4 kJ/kg is at a temperature
of 60°C. It is dropped into 1kg water at 20°C. The final steady state
temperature of water is:
[GATE-1998]
(a) 23.5°C
(b) 300°C
(c) 35°C
(d) 40°C
Thermal Conductivity of MaterialsGATE-4. In descending order of magnitude, the thermal conductivity of
a.
Pure
iron,
[GATE-2001]
b.
Liquid
water,
c. Saturated water vapour, and
d. Pure aluminium can be arranged as
Page 3 of 97
(a) a b c d
(b) b c a d
(c) d a b c
(d) d c b a
Previous 20-Years IES Questions Heat Transfer by ConductionIES-1.
A copper block and an air mass block having similar dimensions are
subjected to symmetrical heat transfer from one face of each block. The
other face of the block will be reaching to the same temperature at a
rate: [IES-2006]
(a) Faster in air block
(b) Faster in copper block
(c) Equal in air as well as copper block
(d) Cannot be predicted with the given information
IES-2.
Consider the following statements:
[IES-1998]
The Fourier heat conduction equation
Q
kA
dT
= −
dx
presumes