# A thick wire is hanging from a wooden table. An anticlockwise magnetic field is to be produced around the wire by passing current through this wire by using a battery. Which terminal of the battery should be connected to the:(a) top end of wire? (b) bottom end of wire? Give reason for your choice.

It is given that a thick wire is hanging from a wooden table. An anticlockwise magnetic field is needed to be produced around the wire by passing current through this wire by using a battery. Then, according to the right-hand thumb rule, current should pass through the wire from bottom end to top end (upwards), because current flows from positive terminal to negative terminal.

So,

(a) The Negative terminal of the battery should be connected to the top end of the wire.

(b) The Positive terminal of the battery should be connected to the bottom end of the wire.

Extra information with the image is posted for the reference only

Maxwell’s right-hand thumb rule indicates the direction of the magnetic field if the direction of current is known.

According to this rule, if we hold the current-carrying wire in our right hand so that our thumb points in the direction of the current, the direction in which our fingers wrap the wire will give the direction of magnetic field lines around the wire.
When thumb points upwards, the wrapped fingers are anticlockwise. So, the direction of the magnetic field is anticlockwise.
When thumb points downwards, the wrapped fingers are clockwise. So, the direction of the magnetic field is clockwise.

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Updated on: 10-Oct-2022

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