A rectangular coil of length 0.12 m and width 0.1 m having 50 turns of wire is suspended vertically in a uniform magnetic field of strength 0.2 Wb/m2. The coil carries a current of 2 A. If the plane of the coil is inclined at an angle of 30o with the direction of the field, the torque required to keep the coil in stable equilibrium will be:
1. 0.15 N-m
2. 0.20 N-m
3. 0.24 N-m
4. 0.12 N-m
A wire carrying current I has the shape as shown in the adjoining figure. Linear parts of the wire are very long and parallel to X-axis while the semicircular portion of radius R is lying in the Y –Z plane. The magnetic field at point O is:
An electron moving in a circular orbit of radius r makes n rotations per second. The magnetic field produced at the centre has a magnitude:
1. μ0ne/2πr
2. zero
3. n2e/r
4. μ0ne/2r
In an ammeter, \(0.2 \%\) of the main current passes through the galvanometer. If the resistance of the galvanometer is \(G,\) the resistance of the ammeter will be:
1. | \({1 \over 499}G\) | 2. | \({499 \over 500}G\) |
3. | \({1 \over 500}G\) | 4. | \({500 \over 499}G\) |
Two identical long conducting wires AOB and COD are placed at a right angle to each other, with one above the other such that 'O' is the common point for the two. The wires carry I1 and I2 currents, respectively. Point 'P' is lying at a distance 'd' from 'O' along a direction perpendicular to the plane containing the wires. What will be the magnetic field at the point "P"?
1.
2.
3.
4.
1. | can be in equilibrium in one orientation. |
2. | can be in equilibrium in two orientations, both the equilibrium states are unstable. |
3. | can be in equilibrium in two orientations, one stable while the other is unstable. |
4. | experiences a torque whether the field is uniform or non-uniform in all orientations. |
When a proton is released from rest in a room, it starts with an initial acceleration a0 towards the east. When it is projected towards the north with a speed of v0, it moves with an initial acceleration of 3a0 towards the east. What are the electric and magnetic fields in the room?
1. | \(\frac{M a_0}{e} \text { west, } \frac{M a_0}{e v_0} u p\) |
2. | \(\frac{M a_0}{e} \text { west, } \frac{2 M a_0}{e v_0} \text { down }\) |
3. | \(\frac{M a_0}{e} \text { east, } \frac{2 M a_0}{e v_0} u p\) |
4. | \(\frac{M a_0}{e} \text { east, } \frac{3 M a_0}{e v_0} \text { down }\) |
Two similar coils of radius \(R\) are lying concentrically with their planes at right angles to each other. The currents flowing in them are \(I\) and \(2I,\) respectively.
What will be the resultant magnetic field induction at the centre?
1. \(\sqrt{5} \mu_0I \over 2R\)
2. \({3} \mu_0I \over 2R\)
3. \( \mu_0I \over 2R\)
4. \( \mu_0I \over R\)
A millivoltmeter of 25 mV range is to be converted into an ammeter of 25 A range. The value (in ohm) of the necessary shunt will be:
1. 0.001
2. 0.01
3. 1
4. 0.05
A current-carrying closed loop in the form of a right isosceles triangle ABC is placed in a uniform magnetic field acting along with AB.
If the magnetic force on the arm BC is F, then what is the force on the arm AC?
1. | -F | 2. | F |
3. | 2F | 4. | -2F |