12th physics chapter 4 Bihar board with NCERT-Details & Highlights
| name of content | 12th physics chapter 4 full solution |
| content | physics objective type MCQ question with answer |
| name of subjects | class 12 physics |
| important for exam | Bihar board & other state board |
| pattern & Level | NCERT & State level question |
12th physics chapter 4 all objective solutions – download PDF
1. 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) It will remain unchanged.
Answer: (d) It will remain unchanged.
2. 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.
Answer: (d) The charged particles and ions in cyclotron can move on any arbitrary path.
3. If an electron is moving with velocity ν⃗ produces a magnetic field B⃗ , then
-
- (a) the direction of field B will be same as the direction of velocity ν .
- (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 .
Answer: (c) the direction of field B will be perpendicular to the direction of velocity ν .
4. 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.
Answer: (b) parallel currents attract and antiparallel cur-rents repel.
5. 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
Answer: (d) r²
6. 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
Answer: b
7. 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
Answer: (d) None of these
8. 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.
Answer: b
9. 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.
Answer: (a) introducing a resistance of large value in series.
10. 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
Answer: (c) both (I) and (II) are correct
11. 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.
Answer: (b) remained stationary.
12. In an inertial frame of reference, the magnetic force on a moving charged particle is F 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
Answer: (c) changed due to change in velocity of charged particle
13. 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.
Answer: (b) Magnetic forces do not obey Newton’s third law.
14. 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
Answer: (b) 4 times
15. 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
Answer: (b) 3 : 2
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Bihar board 12th physics chapter 4 complete objective
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Bihar board 12th science stream subjects wise solution
click here to check out Bihar board science stream all subjects solutions
| SL.N. | Subject name with solutions |
| 01 | Physics |
| 02 | Chemistry |
| 03 | Biology |
| 04 | Math |
| 05 | Hindi |
| 06 | English |