Advertisements
Advertisements
Question
Electromagnets are made of soft iron because soft iron has _______________ .
Options
high retentivity and high coercive force
high retentivity and low coercive force
low retentivity and high coercive force
low retentivity and low coercive force
Solution
low retentivity and low coercive force
Electromagnets are made of soft iron because soft iron has
low retentivity - When soft iron is placed inside a solenoid to make an electromagnet and current is passed through the solenoid,magnetism of the solenoid is incresed thousand folds. When the current is switched off, the magnetism is removed instantly because of the low retentivity of soft iron.
Low coercivity - it has low coercivity so that area under the hysteresis cureve for soft iron is very small hysterisis loss in case of soft iron is small.
APPEARS IN
RELATED QUESTIONS
Why does a compass needle get deflected when brought near a bar magnet?
Consider a magnetic dipole kept in the north to south direction. Let P1, P2, Q1, Q2 be four points at the same distance from the dipole towards north, south, east and west of the dipole respectively. The directions of the magnetic field due to the dipole are the same at
(a) P1 and P2
(b) Q1 and Q2
(c) P1 and Q1
(d) P2 and Q2
When a dielectric is placed in an electric field, it gets polarised. The electric field in a polarised material is less than the applied field. When a paramagnetic substance is kept in a magnetic field, the field in the substance is more than the applied field. Explain the reason of this opposite behaviour.
A rod, when suspended in a magnetic field, stays in the east-west direction. Can we be sure that the field is in the east-west direction? Can it be in the north-south direction?
Pick the correct options.
(a) All electrons have magnetic moment.
(b) All protons have magnetic moment.
(c) All nuclei have magnetic moment.
(d) All atoms have magnetic moment.
The susceptibility of annealed iron at saturation is 5500. Find the permeability of annealed iron at saturation.
An a-particle and a proton of the same kinetic energy are in turn allowed to pass through a magnetic field `vec"B"`, acting normal to the direction of motion of the particles. Calculate the ratio of radii of the circular paths described by them.
The magnetism of a magnet is due to ______
Three identical bar magnets are rivetted together at centre in the same plane as shown in figure. This system is placed at rest in a slowly varying magnetic field. It is found that the system of magnets does not show any motion. The north-south poles of one magnet is shown in the figure. Determine the poles of the remaining two.
