CBSE
In the phenomenon of electric discharge through gases at low pressure, the coloured glow in the tube appears as a result of
excitation of electrons in the atoms
a collision between the atoms of the gas
a collision between the charged particle emitted from the cathode and the atoms of the gas
a collision between the charged particle emitted from the cathode and the atoms of the gas
A conducting circular loop is placed in a uniform magnetic field, B = 0.0025 T with its plane perpendicular to the loop. The radius of the loop is made to shrink at a constant rate of 1 mms-1. The induced emf when the radius is 2 cm, is
2 πμ V
πμ V
πμ V/2
πμ V/2
See the electrical circuit shown in this figure. Which of the following equations is a correct equation for it?
A conducting circular loop is placed in uniform magnetic field 0.04 T with its plane perpendicular to the magnetic field. The radius of the loop starts shrinking at 2 mms-1. The induced emf in the loop when the radius is 2 cm is
3.2 π μ V
4.8 π μ V
0.8 π μ V
0.8 π μ V
Which of the following statement is false or the properties of electromagnetic waves?
Both electric and magnetic field vectors attain the maxima and minima at the same place and same time
The energy in electromagnetic waves is divided equally between electric and magnetic vectors
Both electric and magnetic field vectors are parallel to each other and perpendicular to the direction of propagation of wave
Both electric and magnetic field vectors are parallel to each other and perpendicular to the direction of propagation of wave
The electric field part of an electromagnetic wave in a medium is represented by
Ex = 0;
moving along y direction with frequency 2π x 106 Hz and wavelength 200 m.
moving along x direction with frequency 106 Hz and wavelength 200 m.
moving along x direction with frequency 106 Hz and wavelength 200 m
moving along x direction with frequency 106 Hz and wavelength 200 m
If potential (in volts) in a region is expressed as V (x, y, z) = 6 xy-y +2 yz, the electric field (in N/C) at point (1,1,0) is
A condenser of capacity C is charged to a potential difference of V1. The plates to the condenser are then connected to an ideal inductor of inductance L. The current through the inductor when the potential difference across the condenser reduces to V2 is
Power dissipated in an L-C-R series circuit connected to an AC source of emf is
The thermal emf E in volt of a certain thermocouple is found to vary with temperature difference θ in oC between the two junctions according to the relation
The neutral temperature for the thermocouple will be
450o C
400o C
225o C
225o C