Physics
A copper wire is held between the poles of a magnet. There is a switch provided to reverse the current in the wire. Also, the polarity can be changed. In how many directions can the force act on the wire?
Answer
According to Fleming’s Left Hand Rule, the direction of force on a current-carrying conductor placed in a magnetic field depends on:
- Forefinger → Direction of magnetic field (from North to South)
- Middle finger → Direction of current
- Thumb → Direction of the force (motion) on the wire
In this case:
- The current in the wire can flow in 2 directions (forward or reversed using the switch).
- The magnetic field can also be in 2 directions (from North to South or South to North, depending on polarity).
So, the force on the wire can act in:
2 (current directions) x 2 (field directions) = 4 different directions
Thus, the force on the wire can act in 4 possible directions.
Related Questions
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The given figure shows the path of three particles A, B and C in a uniform magnetic field (perpendicular to the plane of paper outwards). Identify the nature of charges on them. Name the rule you have used
A flat coil ABCD is freely suspended between the pole pieces of a U-shaped permanent magnet with the plane of coil parallel to the magnetic field.
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(d) Name an instrument which makes use of the principle stated above.