Find the direction of magnetic field associated with a current carrying conductor

With the help of a labelled circuit diagram wire, describe an activity to illustrate the pattern of the magnetic field lines around a straight current carrying long conducting wire.

(i) Name the rule that is used to find the direction of magnetic field associated with a current carrying conductor.
(ii) Is there a similar magnetic field produced around a thin beam of moving

  1. alpha particles and
  2. neutrons?

Justify your answer.

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.

(ii)

  1. Yes, alpha particles being positively charged consitutes a current in the direction of motion.
  2. No, Neutron being electrically neutral, constitutes no current.

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