Multiple Choice Questions
1. A metal piece heated to T1 °K. The temperature of the surrounding is T2°K. the heat in
the surrounding due to radiation is proportional to
a) (T14 - T24)
b) (T1 - T2)4
c) (T14 + T24)
d) (T13 - T23)
2. If the temperature of
the sun is doubled. The rate of energy received on the earth will be
increased
by a factor of
a) 2
b) 4
c) 8
d) 16
3. A body in a room cools
from 90°C to 80°C in 5 minutes. the time
taken to cool from 70°C
to 60°C is
a) Less than 5 minute
b) 5 minute
c) More than 5 minutes
d) Less or more than 5 minutes depending upon
the nature of the body
4. 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 3000°K, which of these will
cool fastest?
a) Sphere
b) Cube
c) Plate
d) None
5. The temperature of a
piece of metal is raised from 27°C to 51.2°C. the rate at which
metal radiates energy increases nearly
a) 1.36 times
b) 2.36 times
c) 3.36 times
d) 4.36 times
6. A cup of tea cools from
80°C to 60°C in one minute. The
ambient temperature is 30°C. in
cooling from 60°C to 50°C, it will take.
a) 50 sec
b) 90 sec
c) 60 sec
d) 30 sec
7. Spectrum of a perfectly
black body is
a) Line
spectrum
b) Band spectrum
c) Continuous spectrum
d) None of these
8. An object is at the
temperature of 400°C. at what temperature
would it radiant energy twice
as first? The temperature of surrounding may be
assumed to be negligible
a) 200°C
b) 200°K
c) 800°C
d) 800°K
9. A body at high
temperature T °K radiates heat at rate
proportional to
a) T4
b) T-4
c) T
d) T2
10. Co-efficient of
reflection, coefficient of absorption and coefficient transmission are related
as
a) a + r + 1 = 1
b) a + r + t ¹ 1
c) a + r = -t
d) a ¹ r + 1
