What does the remanence (Br) indicate in a magnetic hysteresis loop?
It is the residual magnetic flux density after removing the applied field.
When a ferromagnetic material is taken through a full magnetising cycle, plotting flux density B against magnetising field H traces a closed hysteresis loop. The loop's shape is characterised by several key points, each with a distinct meaning.
The correct answer identifies remanence Br as the residual magnetic flux density that remains after the applied field H is removed. Starting from saturation and reducing H back to zero, the material does not return to B = 0; a leftover magnetisation persists because the magnetic domains stay partly aligned. That leftover value on the B-axis is the remanence, and it is what gives permanent magnets their strength.
The following comparison distinguishes the main loop parameters:
| Parameter | Meaning on the loop |
|---|---|
| Remanence Br | Value of B when H = 0 (residual flux density) |
| Coercivity Hc | Reverse H needed to bring B back to zero |
| Saturation Bsat | Maximum B the material can reach |
| Loop area | Energy lost as heat per magnetising cycle |
Why the other options are wrong:
- The maximum flux density reached in the loop describes the saturation flux density, which occurs at high H, not at H = 0.
- The applied field needed to reduce flux to zero is the definition of coercivity Hc, a field value on the H-axis, not a residual flux value.
- The area enclosed by the loop represents the hysteresis energy loss per cycle, a completely different quantity from remanence.
Similar Questions
A coil is placed in a uniform magnetic field. If the area of the coil is doubled while the magnetic field strength and orientation remain unchanged, how will the magnetic flux through the coil be affected assuming the initial magnetic flux is a non-zero finite value?
Important Questions from Magnetic Flux Density
The magnetic flux Φ(in Web) linked with a single turn coil at an instant of time t (in second) is given by Φ(t) = 2t 2– 20t + 40. The induced EMF in the coil at the instant t = 2 seconds is
A coil is placed in a uniform magnetic field. If the area of the coil is doubled while the magnetic field strength and orientation remain unchanged, how will the magnetic flux through the coil be affected assuming the initial magnetic flux is a non-zero finite value?
- The ratio of total flux linkage to used flux is known as __________.
The S.I unit of magnetic flux is________
- A flux of 2 mWb passes through a strip of length and breadth 10 cm and 20 cm respectively. It is placed at an angle of 30 degrees to the direction of uniform magnetic field. What is the magnetic flux density (in T)?
