# (a) Draw a sketch to show the magnetic lines of force due to a current-carrying straight conductor.(b) Name and state the rule to determine the direction of magnetic field around a straight current-carrying conductor.

(a) The magnetic lines of force due to a current-carrying straight conductor (wire AB), the magnetic field lines form concentric circles whose centres lie on the wire.

Explanation

In the given figure we have straight vertical wire or conductor AB, passes through a horizontal cardboard sheet. The end of the wire AB is connected to a battery through a switch. When the switch is turned on then, current pass through the wire AB, and it produces magnetic field lines around it, which are circular in nature.

It can be shown by sprinkling iron filings on the cardboard sheet. The sprinkled iron filings get magnetised and on tapping the cardboard sheet, the iron filings arrange themselves in circles around the wire.

A compass placed on the cardboard indicates the direction of the magnetic field.

When the current in the wire flows in the upward direction, then the lines of the magnetic field are in the anticlockwise direction. If the direction of current in the wire flows in the downward direction, then the lines of the magnetic field are in the clockwise direction.

(b) The rule that is used for determining the direction of the magnetic field around a straight current-carrying conductor is Maxwell’s right-hand thumb rule.

According to the rule, the thumb points in the direction of the current, and the direction in which the fingers have surrounded the current-carrying conductor gives the direction of the magnetic field lines around the wire.

Image is posted for reference only.

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Updated on: 10-Oct-2022

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