Activity (Refer circuit diagram given below). Take a battery (12 V), a variable resistance (or a rheostat), an ammeter (0-5 A), 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, as shown in diagram in series with the battery, a plug and key. Sprinkle some iron filings uniformlv on the cardboard. Keep the variable of the rheostat at a fixed position and note the current through the ammeter. Close the key so that a current flows through the wire. Ensure that the copper wire placed between the points X and Y remains vertically straight. Gently tap the cardboard fora few times.
Observe the pattern of the iron filings. It is observed that the iron filings align themselves showing a pattern of concentric circles around the copper wire.
These represent the magnetic field lines.
(i) Right Hand Thumb Rule is used to find the direction of magnetic field associated with a current carrying conductor.
- Yes, alpha particles being positively charged consitutes a current in the direction of motion.
- No, Neutron being electrically neutral, constitutes no current.