The magnetic moment produced in a substance of \(1\text{ gm}\) is \(6 \times 10^{-7}\text{ A-m}^2\). If its density is \(5\text{ gm/cm}^3\), then the intensity of magnetisation in \(A/m\) will be:
1. \(8.3 \times 10^6\)
2. \(3.0\)
3. \(1.2 \times 10^{-7}\)
4. \(3 \times 10^{-6}\)
View Answer
Intensity of magnetisation is \(I = \frac{M}{V} = \frac{M\rho}{m}\). Given \(m = 1\text{ gm}\), \(M = 6 \times 10^{-7}\text{ A-m}^2\), \(\rho = 5 \times 10^3\text{ kg/m}^3\). Thus \(I = \frac{6 \times 10^{-7} \times 5 \times 10^3}{10^{-3}} = 3.0\text{ A/m}\).
If magnetic field in space is \(1\text{ T } \hat{i}\), electric field is \(10\text{ N/C } \hat{i}\), no gravitational field is present and a charged particle is released from rest from origin, it will:
1. not move at all
2. move in circular path
3. move in a helical path
4. move on a straight line
View Answer
Since the particle starts from rest, its initial magnetic force is zero. The electric field accelerates it along \(\hat{i}\). Because velocity remains parallel to the magnetic field, the magnetic force remains zero, and it continues on a straight line.
Statement-1: In an isolated conductor, free electrons keep on moving but no net magnetic force acts on a conductor in a magnetic field.
Statement-2: In a conductor, the average velocity of thermal motion of electrons is zero. Hence no current flows through the conductor.
1. Both Statement-1 and Statement-2 are true and Statement-2 is the correct explanation of Statement-1.
2. Both Statement-1 and Statement-2 are true but Statement-2 is not correct explanation of Statement-1.
3. Statement-1 is true but Statement-2 is false.
4. Statement-1 and Statement-2 are false.
View Answer
The net magnetic force on a current-carrying conductor is given by \(F = I L B\). Since average velocity of thermal motion is zero, current \(I = 0\), resulting in zero net force.