1
WB JEE 2021
MCQ (Single Correct Answer)
+2
-0.5
Change Language
A uniform rod of length L pivoted at one end P is freely rotated in a horizontal plane with an angular velocity $$\omega$$ about a vertical axis passing through P. If the temperature of the system is increased by $$\Delta$$T, angular velocity becomes $${\omega \over 2}$$. If coefficient of linear expansion of the rod is $$\alpha$$($$\alpha$$ << 1), then $$\Delta$$T will be
A
$${1 \over \alpha }$$
B
$${1 \over 2\alpha }$$
C
$${1 \over 4\alpha }$$
D
$$\alpha$$
2
WB JEE 2021
MCQ (Single Correct Answer)
+2
-0.5
Change Language
An ideal gas of molar mass M is contained in a very tall vertical cylindrical column in the uniform gravitational field. Assuming the gas temperature to be T, the height at which the centre of gravity of the gas is located is (R$$\to$$universal gas constant)
A
$${{RT} \over g}$$
B
$${{RT} \over Mg}$$
C
MgR
D
RTg
3
WB JEE 2021
MCQ (Single Correct Answer)
+2
-0.5
Change Language
Under isothermal conditions, two soap bubbles of radii a and b coalesce to form a single bubble of radius c. If the external pressure is p, then surface tension of the bubbles is
A
$${{p({c^3} - {a^3} + {b^3})} \over {4({a^2} + {b^2} - {c^2})}}$$
B
$${{p({c^3} - {a^3} - {b^3})} \over {4({a^2} + {b^2} - {c^2})}}$$
C
$${{p({c^2} + {a^3} - {b^2})} \over {4({a^3} + {b^3} - {c^3})}}$$
D
$${{p({a^3} + {b^3} - {c^3})} \over {4({a^2} + {b^2} - {c^2})}}$$
4
WB JEE 2021
MCQ (More than One Correct Answer)
+2
-0
Change Language
WB JEE 2021 Physics - Magnetism Question 11 English
A small bar magnet of dipole moment M is moving with speed v along x-direction towards a small closed circular conducting loop of radius a with its centre O at x = 0 (see figure). Assume x >> a and the coil has a resistance R. Then, which of the following statements is/are true?
A
Magnetic field at the centre O of the circular coil due to the bar magnet is $${M \over {{x^3}}}$$
B
Induced emf is proportional to $${1 \over {{x^4}}}$$
C
The magnetic moment $$\mu$$ due to induced current in the coil is proportional to a4
D
The heat produced is proportional to $${1 \over {{x^6}}}$$
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