Question

A coil is connected to a 1.5V battery. Now this battery is replaced by a 3V battery. The magnetic field around the coil is
A) Increases
B) Decreases
C) Does not change
D) May increase or decrease

Answer 1

Hint: The voltage increases the current flowing through the same coil increases.

Complete step by step solution:
1.The amount of current in a circuit depends on the amount of voltage and the amount of resistance in the circuit to oppose current flow.
2.The magnitude of magnetic field is directly proportional to the magnitude of current through the coil, i.e. B ∝ I
So, from point 1 and 2
We can deduce that the magnetic field around the coil increases because as the voltage increases the current flowing through the same coil increases thereby increasing the magnetic field.

Correct answer: A) Increases

Note: If resistance remains constant in the circuit, when voltage increases, current must also increase. Since the strength of the magnetic field is directly related to the current in the wire, the magnitude of the magnetic field would increase with an increase in voltage in the circuit.