Moving Charges and Magnetism
3 solved NEET Physics previous year questions on Moving Charges and Magnetism, each with the correct answer and a full explanation.
Q1
A current flows along the length of an infinitely long, straight, thin-walled pipe. Then
✓ Correct answer: b) the magnetic field at any point inside the pipe is zero
ExplanationUsing Ampere’s circuital law over a circular loop of any radius less than the radius of the pipe, we can see that net current inside the loop is zero.Hence, magnetic field at every point inside the loop will be zero.
Q2
To convert a galvanometer into a voltmeter one should connect a:
✓ Correct answer: a) high resistance in series with galvanometer
ExplanationA voltmeter is an instrument used to measure the electrical potential difference between two points in an electrical circuit.Analog voltmeters shift the pointer over a scale in relation to the voltage of the circuit.The fundamental theory of the voltmeter is that it must be wired parallel to the voltage that we want to calculate.The parallel connection is used as the voltmeter is built in such a way that it has a very high resistance value.In order to convert a galvanometer to a voltmeter, a high resistance is connected to it in series.Since voltmeter can measure the potential voltage more accurately only with the help of high resistance.
Q3
A long solenoid is formed by winding 70 turns cm–1. If 2.0 A current flows, then the magnetic field produced inside the solenoid is _______ ( 0 = 4 10–7 TmA–1) [JEE Main 2023, 24 Jan (Shift 2)]
✓ Correct answer: b) 176 10–4 T
ExplanationGiven, Number of turns in solenoid (n) = 70 turns cm– 1 Flow of current (i) = 2 A We know that, B = 0 ni B = 4 × 10–7 B = 4 × 10–5 70 × 2 B = 17.58 x 10–3 T B = 176 X 10–4 T Hence, magnetic field produce inside the solenoid (B) = 176 X 10–4 T.
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