The length of a wire of a potentiometer is 100 cm, and the emf of its stand and cell is E volt. It is employed to measure the emf of a battery whose internal resistance is 0.52 Ω.1fthe balance point is obtained at l= 30 cm from the positive end, the emf of the battery is
The magnetic lines of force inside a bar magnet
are from north-pole to south-pole of the magnet
do not exist
depend upon the area of cross-section of the bar magnet
are from south-pole to north-pole of the magnet
Curie temperature is the temperature above which
a ferromagnetic material becomes paramagnetic
a paramagnetic material becomes diamagnetic
a ferromagnetic material becomes diamagnetic
a paramagnetic material becomes ferromagnetic
A particle of mass M and charge Q moving with velocity describes a circular path of radius R when subjected to a uniform transverse magnetic field of induction B. The work done by the field when the particle completes one full circle is.
zero
BQ 2R
BQv 2R
B.
zero
When particle describes circular path in a magnetic field, its velocity is always perpendicular to the magnetic force.
Power, P = = Fv cosθ
Here, θ = 90°
∴ P = 0
But P =
W = P . t
Hence, work done W = 0 [everywhere]
An L-C-R series circuit consists of a resistance of 10 Ω a capacitor of reactance 6.0 Ω and an inductor coil. The circuit is found to resonate when put across a 300 V, 100 Hz supply. The inductance of coil is (take = 3)
0.1 H
0.01 H
0.2 H
0.02 H
Two coherent monochromatic light beams of intensities I and 9I are superimposed.The maximum and the minimum intensities of the resultant beams are
10 I and zero
10 I and 8 I
10 I and 4 I
16 I and 4 I
In a single slit diffraction pattern, the distance between the first minimum on the left and the first minimum on the right is 5 mm. The screen on which the diffraction pattern is displayed is at a distance of 80 cm from the slit. The, wavelength is 6000 A. The slit width (in mm) is about
0.576
0.348
0.192
0.096
When a ray is incident on a medium of refractive index n at Brewster's angle,it gets
totally reflected
totally absorbed
circularly polarised
plane polarised
The energy gap between the valence band and the conduction band for a material is 6 eV. The material is
an insulator
a metal
an intrinsic semiconductor
a superconductor
An AC signal of 50 Hz frequency is input of a full wave rectifier using two diodes. The output frequency after full wave rectification is
25 Hz
50 Hz
100 Hz
200 Hz