Two spheres of same metal have radii a and b. Thet have been connected to a conducting wire. Find the ratio of the electric field intensity upon them.
a/b
b/a
b2 / a
b2/a2
If in a circuit current lags behind EMF by . Then it is a/an
resistor circuit
capacitor
inductor circuit
CR circuit
C.
inductor circuit
Figure shows a purely inductive circuit, in which a sinusoidal emf is applied. The induced emf across the inductor is so that from Kirchoff's law.
εo sinωt L = 0
⇒ = sinωt
⇒ i = + C
The constant C can be shown to be zero from the fact that, the emf being sinusoidal, the current should also be so, and the average current over one time period has to be zero.
∴ i = sin
which shows that the current lags behind the emf by a phase of .
If a unit positive charge is taken from one point to another over an equipotential surface, then
work is done on the charge
work is done by the charge
work done is constant
no work is done
Figure shows the electric lines of forces emerging from a charged body. If the electric field at A and B are EA and EB respectively and if the displacement between A and B is r, then
EA > EB
EA < EB
EA = EB/r
EA = EB / r2
A small piece of metal wire is dragged across the gap between the pole pieces of a magnet in 0.4 sec. If magnetic flux between the pole pieces is known to be 8 × 10-4 Wb, then induced emf in the wire, is
4 × 10-3 V
8 × 10-3 V
20 × 10-3 V
6 × 10-3 V
Two coherent monochromatic light beams of amplitude 3 and 5 units are superposed. The maximum and minimum possible intensities in the resulting beams are in the ratio
4 : 2
16 : 1
8 : 2
4 : 2