Describe an activity to determine the direction of magnetic field produced by a current carrying straight conductor. Also show that the direction of the magnetic field is reversed on reversing the direction of current.

Describe an activity to determine the direction of magnetic field prod

1.	Describe an activity to determine the direction of magnetic field produced by a current carrying straight conductor. Also show that the direction of the magnetic field is reversed on reversing the direction of current.
Answer» Solution :Take a battery (12 V), a variable resistance (or a rheostat), an AMMETER (0 - 5A), a plug key and a long straight thick copper wire. Insert the thick wire through the centre, normal to the plane of a rectangular CARDBOARD. Take care that the cardboard is FIXED and does not slide up or down. Connect the copper wire vertically between the points X and Y, in series with the battery, a plug and key. Sprinkle some iron fillings uniformly on the cardboard. Keep the variable of the rheostat at a fixed position and note the current through ammeter. Close the key, so that current flows through the wire. Ensure that the copper wire placed between the points X and Y remains vertically straight. Gently tap the cardboard for a few times. Observe the pattern of the iron filings. You would FIND that the iron filings align themselves showing a pattern of concentric circles around the copper wire. This represents the magnetic field around the current- carrying conductor. The direction of magnetic field CHANGES on reversing the direction of current.