Question

Describe an activity to show that a current carrying conductor, placed in an external magnetic field experiences a force.

Hint:

Use aluminum rod, horseshoe magnet, battery. Current-carrying rod in magnetic field moves. Reverse current or magnetic field \(\Rightarrow\) reverse force direction. Fleming's Left Hand Rule gives force direction.

Answer 1

Step 1: Materials required.

• A strong horseshoe magnet
• A straight aluminum rod (or copper rod)
• A battery (6V or 12V)
• Connecting wires
• A switch
• A stand to hold the rod

Step 2: Setup of the activity.

• Place the horseshoe magnet on a table such that the poles are vertical (north pole above, south pole below, or vice versa).
• Suspend the aluminum rod horizontally using the stand so that it hangs freely between the poles of the magnet, perpendicular to the magnetic field.
• Connect the rod in series with the battery, switch, and connecting wires.

Step 3: Procedure.

• Keep the switch open initially (no current).
• Observe the position of the rod.
• Close the switch to allow current to flow through the rod.
• Observe what happens to the rod.
• Reverse the direction of current by interchanging battery connections and observe again.
• Reverse the direction of magnetic field (flip the magnet poles) and observe.

Step 4: Observations.

• When current flows, the rod gets displaced (moves) from its original position.
• The direction of displacement depends on the direction of current and the direction of magnetic field.
• If current or magnetic field direction is reversed, the direction of force (displacement) also reverses.
• If both current and magnetic field are reversed simultaneously, the direction of force remains the same.

Step 5: Conclusion.

• A current-carrying conductor placed in a magnetic field experiences a force.
• The force is maximum when the conductor is perpendicular to the magnetic field.
• The direction of force is given by Fleming's Left Hand Rule.

Step 6: Fleming's Left Hand Rule.
Stretch the thumb, forefinger, and middle finger of your left hand mutually perpendicular to each other. If the forefinger points in the direction of magnetic field and the middle finger points in the direction of current, then the thumb points in the direction of force (motion).
Step 7: Final answer.
The activity demonstrates that a current-carrying conductor in a magnetic field experiences a force, whose direction is given by Fleming's Left Hand Rule.