Advertisements
Advertisements
Question
State the conditions when the magnetic potential energy of a magnetic dipole (current-carrying coil) kept in the uniform magnetic field be minimum and maximum.
Solution
- Condition for minimum magnetic potential energy:
In a magnetic field when `vec"m"` and `vec" B"` are parallel to each other, the magnetic potential energy of a magnetic dipole is minimum.
Mathematically, when θ = 0, U = -m B cos 0° = -m B
Minimum potential energy - Condition for maximum magnetic potential energy:
When `vec"m"` and `vec" B"` are antiparallel to each other, the magnetic potential energy of a magnetic dipole is maximum.
Mathematically, when θ = 180°, U = -m B cos 180° = m B
Maximum potential energy
APPEARS IN
RELATED QUESTIONS
When the magnetic dipole is rotated through angle `theta`, work done in rotating dipole is given by -mB cos `theta`. Now, a magnetic needle lying parallel to a magnetic field requires W units of work to tum it through 60°. What will be the value of torque needed to maintain the needle in same position?
Six very long insulated copper wires are bound together to form a cable. The currents carried by the wires are I1 = +10 A, I2 = -12 A, I3 = +10A, I4 = +8 A, I5 = -11 A and I6 = 19 A. The magnetic induction at a perpendicular distance of 20 cm from the cable is ______.
A short bar magnet of moment 0.5.A m2 is suspended in a horizontal magnetic field of 1000 gauss such that it can rotate freely in a horizontal plane. Calculate (i) the magnitude of the torque and (ii) the magnetic potential energy when its angular displacement with respect to the direction of the field is 10°.
