1
NEET 2018
MCQ (Single Correct Answer)
+4
-1
Change Language
A thin diamagnetic rod is placed vertically between the poles of an electromagnet. When the current in the electromagnet is switched on, then the diamagnetic rod is pushed up, out of the horizontal magnetic field. Hence the rod gains gravitational potential energy. The work required to do this comes from
A
The current source
B
The magnetic field
C
The lattice structure of the material of the rod
D
The induced electric field due to the changing magnetic field
2
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
$${{81} \over {256}}$$
3
NEET 2018
MCQ (Single Correct Answer)
+4
-1
Change Language
A solid sphere is rotating freely about its symmetry axis in free space. The radius of the sphere is increased keeping its mass same. Which of the following physical quantities would remain constant for the sphere?
A
Angular velocity
B
Moment of inertia
C
Rotational kinetic energy
D
Angular momentum
4
NEET 2018
MCQ (Single Correct Answer)
+4
-1
Change Language
A tuning fork is used to produce resonance in a glass tube. The length of the air column in this tube can be adjusted by a variable piston. At room temperature of 27°C two successive resonances are produced at 20 cm and 73 cm of column length. If the frequency of the tuning fork is 320 Hz, the velocity of sound in air at 27°C is
A
330 m s–1
B
339 m s–1
C
350 m s–1
D
300 m s–1