Q. A charged particle is moving in a cyclotron, what effect on the radius of path of this charged particle will occur when the frequency of the ratio frequency field is doubled?
-
(A)
It will also be doubled.
-
(B)
It will be halved.
-
(C)
It will be increased by four times.
-
(D)
t will remain unchanged.
✅ Correct Answer: (D)
t will remain unchanged.
Q. Which of the following is not correct about cyclotron?
-
(A)
It is a machine to accelerate charged particles or ions to high energies.
-
(B)
Cyclotron uses both electric and magnetic fields in combination to increase the energy of charged particles.
-
(C)
The operation of the cyclotron is based on the fact that the time for one revolution of an ion is independent of its speed or radius of its orbit.
-
(D)
The charged particles and ions in cyclotron can move on any arbitrary path.
✅ Correct Answer: (D)
The charged particles and ions in cyclotron can move on any arbitrary path.
Q. If an electron is moving with velocity ν⃗ produces a magnetic field B⃗ , then
-
(A)
the direction of field B⃗ will be same as the direction of velocity ν⃗
-
(B)
the direction of field B⃗ will be opposite to the direction of velocity ν⃗
-
(C)
the direction of field B⃗ will be perpendicular to the direction of velocity ν⃗ .
-
(D)
the direction of field B⃗ does not depend upon the direction of velocity ν⃗
✅ Correct Answer: (C)
the direction of field B⃗ will be perpendicular to the direction of velocity ν⃗ .
Q. The nature of parallel and anti-parallel currents are
-
(A)
parallel currents repel and antiparallel cur¬rents attract.
-
(B)
parallel currents attract and antiparallel cur-rents repel.
-
(C)
both currents attract.
-
(D)
both currents repel
✅ Correct Answer: (B)
parallel currents attract and antiparallel cur-rents repel.
Q. The magnetic moment of a current I carrying circular coil of radius r and number of turns N varies as
-
(A)
1r²
-
(B)
1r
-
(C)
r
-
(D)
r²
Q. A short bar magnet has a magnetic moment of 0. 65 J T-1 , then the magnitude and direction of the magnetic field produced by the magnet at a distance 8 cm from the centre of magnet on the axis is
-
(A)
2.5 × 10-4 T, along NS direction
-
(B)
2.5 × 10-4 T along SN direction
-
(C)
4.5 × 10-4 T, along NS direction
-
(D)
4.5 × 10-4 T, along SN direction
✅ Correct Answer: (B)
2.5 × 10-4 T along SN direction
Q. A current carrying loop is placed in a uniform magnetic field. The torqe acting on it does not depend upon
-
(A)
area of loop
-
(B)
value of current
-
(C)
magnetic field
-
(D)
None of these
✅ Correct Answer: (D)
None of these
Q. A moving coil galvanometer can be converted into an ammeter by
-
(A)
introducing a shunt resistance of large value in series.
-
(B)
introducing a shunt resistance of small value in parallel.
-
(C)
introducing a resistance of small value in series.
-
(D)
introducing a resistance of large value in parallel.
✅ Correct Answer: (B)
introducing a shunt resistance of small value in parallel.
Q. The conversion of a moving coil galvanometer into a voltmeter is done by
-
(A)
introducing a resistance of large value in series
-
(B)
introducing a resistance of small value in parallel
-
(C)
introducing a resistance of large value in parallel
-
(D)
introducing a resistance of small value in series
✅ Correct Answer: (A)
introducing a resistance of large value in series
Q. When a magnetic compass needle is carried nearby to a straight wire carrying current, then
(I) the straight wire cause a noticeable deflection in the compass needle.
(II) the alignment of the needle is tangential to an imaginary circle with straight wire as its centre and has a plane perpendicular to the wire
-
(A)
(I) is correct
-
(B)
(II) is correct
-
(C)
both (I) and (II) are correct
-
(D)
neither (I) nor (II) is correct
✅ Correct Answer: (C)
both (I) and (II) are correct
Q. A strong magnetic field is applied on a stationary electron. Then the electron
-
(A)
moves in the direction of the field.
-
(B)
remained stationary.
-
(C)
moves perpendicular to the direction of the field.
-
(D)
moves opposite to the direction of the field.
✅ Correct Answer: (B)
remained stationary.
Q. In an inertial frame of reference, the magnetic force on a moving charged particle is F⃗ Its value in another inertial frame of reference will be
-
(A)
remained same
-
(B)
changed due to change in the amount of charge
-
(C)
changed due to change in velocity of charged particle
-
(D)
changed due to change in field direction
✅ Correct Answer: (C)
changed due to change in velocity of charged particle
Q. Which one of the following is correct statement about magnetic forces?
-
(A)
Magnetic forces always obey Newton’s third law.
-
(B)
Magnetic forces do not obey Newton’s third law.
-
(C)
For very high current, magnetic forces obey Newton’s third law.
-
(D)
Inside low magnetic field, magnetic forces obey Newton’s third law.
✅ Correct Answer: (B)
Magnetic forces do not obey Newton’s third law.
Q. A charged particle is moving on circular path with velocity v in a uniform magnetic field B, if the velocity of the charged particle is doubled and strength of magnetic field is halved, then radius becomes
-
(A)
8 times
-
(B)
4 times
-
(C)
2 times
-
(D)
16 times
✅ Correct Answer: (B)
4 times
Q. Two a-particles have the ratio of their velocities as 3 : 2 on entering the field. If they move in different circular paths, then the ratio of the radii of their paths is
-
(A)
2 : 3
-
(B)
3 : 2
-
(C)
9 : 4
-
(D)
4 : 9
✅ Correct Answer: (B)
3 : 2
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