Question

For the circuit shown below, if we want to change the direction in which the magnetic needle gets deflected, then which of the following can be done?​

• A. Increasing the length of wire ​
• B. Increasing the current in the wire​
• C. Reversing the polarity of the battery​
• D. Decreasing the length of wire​

Answer 1

The correct option is C Reversing the polarity of the battery​

A wire or a conductor carrying current develops a magnetic field. The direction of the magnetic field is perpendicular to the direction of the flow of current. To change the direction of a magnetic needle, we need to change the direction of the magnetic field. Increasing or decreasing the length of wire or increasing the current in the wire do not change the direction of the magnetic field. Changing the polarity of the battery will change the direction of current and magnetic field. Hence, reversing the polarity of the battery will change the direction of the magnetic needle.