Multiple Choice QuestionsA wire of resistance 12 Ωm-1 is bent to form a complete circle of radius 10 cm. The resistance between its two diametrically opposite point, A and B as shown in the figure, is
0.6 π Ω
3 π Ω
6 π Ω
6 π Ω
A student measures the terminal potential difference (V) of a cell (of emf and internal resistance r) as a function of the current (I) flowing through it. The slope and intercept of the graph between V and I, then respectively, equal
The magnetic force acting on a charged particle of charge -2 μC in a magnetic field of 2T acting in y direction, when the particle velocity is 
8N in -z direction
4N in z direction
8 N in y direction
8 N in y direction
A particle mass m, charge Q and kinetic energy T enter a transverse uniform magnetic field of induction.
After 3 s the kinetic energy of the particle will be
3T
2T
T
T
A long solenoid has 500 turns. When a current of 2 A is passed through it, the resulting magnetic flux linked with each turn of the solenoid is 4 x 10-3 Wb. The self -inductance of the solenoid is
2.5 H
2.0 H
1.0 H
1.0 H
A galvanometer of resistance 50 Ω is connected to a battery of 3 V along with a resistance of 2950 Ω in series. A full-scale deflection of 30 divisions is obtained in the galvanometer. In order to reduce this deflection to 20 divisions, the resistance in series should be
5050 Ω
5550 Ω
6050 Ω
6050 Ω
Two circular coils 1 and 2 are made from the same wire but the radius of the 1st coil is twice that of the 2nd coil. What is the ratio of potential difference applied across them so that the magnetic field at their centres is the same?
3
4
6
6
A long solenoid of diameter 0.1 m has 2 × 104 turns per meter. At the centre of the solenoid, a coil of 100 turns and radius 0.01 m is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to 0 A from 4 A in 0.05 s. If the resistance of the coil is 10π2 Ω, the total charge flowing through the coil during this time is
32 πμC
16 μC
32 μC
32 μC
Current sensitivity of a moving coil galvanometer is 5 div/mA and its voltage sensitivity (angular deflection per unit voltage applied) is 20 div/V. The resistance of the galvanometer is
40 Ω
25 Ω
500 Ω
250 Ω
A metallic rod of mass per unit length 0.5 kg m–1 is lying horizontally on a smooth inclined plane which makes an angle of 30° with the horizontal. The rod is not allowed to slide down by flowing a current through it when a magnetic field of induction 0.25 T is acting on it in the vertical direction. The current flowing in the rod to keep it stationary is
7.14 A
5.98 A
11.32 A
14.76 A
