1
NEET 2018
MCQ (Single Correct Answer)
+4
-1
Change Language
The power radiated by a black body is P and it radiates maximum energy at wavelength, $$\lambda $$0 . If the temperature of the black body is now changed so that it radiates maximum energy at wavelength $${3 \over 4}{\lambda _0}$$, the power radiated by it becomes nP. The value of n is
A
$${3 \over 4}$$
B
$${4 \over 3}$$
C
$${{256} \over {81}}$$
D
$${{81} \over {256}}$$
2
NEET 2018
MCQ (Single Correct Answer)
+4
-1
Change Language
Two wires are made of the same material and have the same volume. The first wire has cross-sectional area A and the second wire has cross-sectional area 3A. If the length of the first wire is increased by $$\Delta $$l on applying a force F, how much force is needed to stretch the second wire by the same amount?
A
6F
B
F
C
9F
D
4F
3
NEET 2018
MCQ (Single Correct Answer)
+4
-1
Change Language
A small sphere of radius ‘r’ falls from rest in a viscous liquid. As a result, heat is produced due to viscous force. The rate of production of heat when the sphere attains its terminal velocity, is proportional to
A
r3
B
r2
C
r5
D
r4
4
NEET 2017
MCQ (Single Correct Answer)
+4
-1
Change Language
A spherical black body with a radius of 12 cm radiates 450 watt power at 500 K. If the radius were halved and the temperature doubled, the power radiated in watt would be
A
450
B
1000
C
1800
D
225
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