2, 4 and 6 S are the conductances of three conductors. When they are joined in parallel, their equivalent conductance will be
12 S
( 1/12 ) S
( 12 /11 ) S
11/12 S
Two parallel long wires A and B carry currents i1 and i2 ( < i2 ). When i1 and i2 are in the same direction, the magnetic field at a point mid way between the wires is 10 µT. If i2 is reverse the field becomes 30 µT. The ratio i1 / i2
1
2
3
4
Two conducting circular loops of radii R1 and R2 are placed in the same plane with their centres coinciding. If R1 > R2, the mutual inductance M between them will be directly proportional to
The most suitable metal for making electromagnets and transformer cores is
steel
iron
copper
aluminium
An inductive circuit contains a resistance of 10 Ω and an inductance of 2 H, If an AC voltage of 120 V and frequency 60 Hz is applied to this circuit, the current would be nearly
0.72 A
0.16 A
0.48 A
0.80 A
The diameter of the plate of a parallel plate condenser is 6 cm. If its capacity is equal to that of a sphere of diameter 200 cm, the separation between the plates of the condenser is
4·5 × 10-4 m
2·25 × 10-4 m
6·75 × 10-4 m
9 × 10-4 m
B.
2·25 × 10-4 m
The capacity of the parallel plate capacitor which is
C = .....(i)
is equal to the capacitance of the sphere of radius R and the self-capacitance of the sphere of radius R and the self-capacitance of the conducting sphere of radius R is given as
C = 4ε0R ....(ii)
By equating equation (i) and (ii)
=
⇒ d =
=
⇒ d = 2.25 × 10-2 cm
d = 2.25 × 10-4 m
In a uniform electric field a charge of 3 C experiences a force of 3000 N. The potential difference between two points 1 cm apart along the electric line of force will be
10 V
30 V
300 V
100 V
A long straight wire carries 10 A d.c. current an electron travels perpendicular to the plane of this wire at a distance 0.1 m with velocity 5.0 x 106 ms-1. Force acting on the electron due to current in wire is
zero N
0·6 × 10-17 N
2.4 × 10-17 N
2.2 × 10-17 N
A particle of charge q and mass m starts moving from the origin under the action of an electric field = E0 and velocity . The speed of the particle will become after a time
Assertion: Long distance transmission of a.c. is carried out at extremely high voltages.
Reason: Because when the distance is large, voltage has to be large.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.