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
D.
As V ∝ l
∴
where, l = balance point,
L = length of potentiometer wire
or V =
V =
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
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