An air-plane with 20m wing spread is flying at straight south parallel to the earth’s surface. The earth’s magnetic field has a horizontal component of and the dip angle is 60º. Calculate the induced emf between the plane tips is:
1. 0.174 V
2. 0.173 V
3. 1.173 V
4. 0.163 V
A wire of fixed lengths is wound on a solenoid of length and radius r. Its self inductance is found to be L. Now if same wire is wound on a solenoid of length and radius r/2, then the self inductance will be –
1.
2.
3.
4.
A wire in the form of a circular loop of radius 10 cm lies in a plane normal to a magnetic field of 100 T. If this wire is pulled to take a square shape in the same plane in 0.1 s, average induced emf in the loop is:
1. 6.70 volt
2. 5.80 volt
3. 6.75 volt
4. 5.75 volt
A superconducting loop of radius R has self inductance L. A uniform and constant magnetic field B is applied perpendicular to the plane of the loop. Initially current in this loop is zero. The loop is rotated by 180°. The current in the loop after rotation is equal to –
1. zero
2.
3.
4.
A coil of inductance 8.4 mH and resistance 6 is connected to a 12 V battery. The current in the coil is 1.0 A at approximately the time.
1. 500 ms
2. 20 ms
3. 35 ms
4. 1 ms
PQ is an infinite current carrying conductor. AB and CD are smooth conducting rods on which a conductor EF moves with constant velocity v as shown. The force needed to maintain constant speed of EF is –
1.
2.
3.
4.
A 50 turns circular coil has a radius of 3 cms, it is kept in a magnetic field acting normal to the area of the coil. The magnetic field B increased from 0.10 tesla to 0.35 tesla in 2 milliseconds. The average induced emf in the coil is-
1. 1.77 volts
2. 17.7 volts
3. 177 volts
4. 0.177 volts
A semicircular wire of radius R is rotated with constant angular velocity about an axis passing through one end and perpendicular to the plane of the wire.
There is a uniform magnetic field of strength B. The induced emf between the ends is -
1.
2.
3. is variable
4. none of these
The inductance of a closed-packed coil of 400 turns is 8 mH. A current of 5 mA is passed through it. The magnetic flux through each turn of the coil is approximately-
1.
2.
3.
4.
Loop A of radius (r << R) moves towards loop B with a constant velocity v in such a way that their planes are always parallel.
What is the distance (x) between the two loops when the induced emf in loop A is maximum –
1.
2.
3.
4.