Question

Draw a diagram showing the direction of the magnetic field lines due to a straight wire carrying current. Also, show the direction of the current in the wire.

Answer 1

Hint: When a current passes through a conductor, a magnetic field is generated. The magnetic field is generally represented by concentric circles. Using hand, we can define the direction of the electric current and magnetic field. Use the right-hand thumb rule to define directions.

Complete answer:

When an electric current flows through a conductor made of any kind of material, an EMF is induced in the conductor and the induced EMF is created which in turn creates a magnetic field around it. The magnetic field lines form concentric circles around the conductor as shown in the figure. The direction of the magnetic field is perpendicular to the wire and it is in the direction of wrapped fingers of the right hand holding the conductor. The thumb pointing upwards indicates the direction of the current.
When the current flows in the anti-clockwise direction then the magnetic field implies that the existence of poles and the polarity of a current-carrying conductor is north-south. When a magnetic compass with the north end is brought closer to the 1st end of the conductor then the needle deflects towards the west i.e. away from the conductor. Because the magnetic compass that is pointing in the direction of the earth's magnetic field, (i.e. north-south direction) repels with the north pole of the current-carrying conductor. Like poles repel each other. This is the fundamental principle of magnetism solution.

Note:
We know that a magnetic field is produced around a straight current-carrying conductor. If the current is unchanged, this magnetic field reduces since the distance from the wire increases. Therefore, the concentric circles representing the magnetic lines of force are shown bigger and rarefied as the distance from the wire increases. If the current through the wire is increased, the intensity of the magnetic field increases.