A rectangular current loop in a uniform magnetic field feels a torque. What is the net force on the loop?
AZero, the side forces cancel
BZero, but only at 90 degrees
CEqual to IlB on the whole loop
DEqual to NIAB on the whole loop
Answer & Solution
Correct answer: A. Zero, the side forces cancel
1. Current runs one way along one side of the loop and the opposite way along the other side.
2. Right hand rule 1 then gives forces on the two sides that are equal in size and opposite in direction.
3. Those forces cancel, so the net force from the sides is zero.
4. The forces on the top and bottom segments are also equal and opposite, so they cancel as well.
5. The two side forces still act at different places, so they leave a torque even though the net force vanishes.
_Source: OpenStax College Physics (CC BY 4.0), Ch 22 "Magnetism", section 22.8 Torque on a Current Loop: Motors and Meters_
Keep practising Magnetism
Browse all Magnetism questions for B.Tech EEE, or explore more Electrical Engineering topics.
Related questions
For which task are x ray images more effective than MRI images?Which sensor, operating at liquid helium temperature, can measure fields thousands of timeWhat is a recording of the magnetic field of the beating heart called?What does functional MRI actually detect when it maps activity in the brain?Nuclear magnetic resonance was formulated in 1946. Who received the 1952 Nobel Prize in PhWhat is the largest part of an MRI unit, and what field strength does it typically produceHow is the electron beam of a cathode ray tube aimed at a chosen point on the screen?Wires of infinite length cannot be built. How is the definition of the ampere realised in