The coupling co-efficient of the perfectly coupled coils is:
  • Zero
  • 1
  • slightly more than 1
  • infinite
1 henry is equal to :
  • \(\frac{weber}{ampere}\)
  • \(\frac{weber}{Volt}\)
  • weber ampere
  • None of these
The magnetic field is parallel to a surface, then the magnetic flux through the surface is :
  • zero
  • small but not zero
  • infinite
  • large but not infinite
In the expression e = -\(\frac{d∅}{dt}\), the -ve sign signifies:
  • The induced emf is produced only when magnetic flux decreases
  • The induced emf opposes the change in the magnetic flux
  • The induced emf is opposite to the direction of the flux
  • None of these
An e- and a p- are moving parallel to each other in a magnetic field. The magnetic force acting on the p+ is:
  • 1840 times that on e-
  • less than that of e-
  • same as that of e-
  • slightly more than that of e-
Which of the following is not equal to a henry?
  • \(\frac{Volt second}{ampere}\)
  • \(\frac{Volt second^2}{Coulomb}\)
  • \(\frac{Volt^2 second}{Coulomb}\)
  • \(\frac{Jole second}{Coulomb^2}\)
A transformer is used to light 100 W and 110 V lamp from a 220 V mains. If the main current is 0.5 A. Then the efficiency of the transformer is:
  • 11%
  • 50%
  • 80%
  • 90%
The magnetic flux (∅) linked with a coil is related to the number of turns (N) ofthe coil as:
  • f ∝ N
  • f ∝ N-1
  • f ∝ N2
  • f ∝ N-2
The magnetic flux (∅) lined with a coil is related to its area (s) as:
  • ∅ ∝ s
  • ∅ ∝ s²
  • ∅ ∝ s1/2
  • ∅ ∝ s-1/2
If the magnetic flux linked with a coil through which a current off ampere is set up is ∅, then the coefficient of self-inductance of the coil is:
  • \(\frac{l}{∅}\)
  • \(\frac{∅}{l}\)
  • ∅l
  • None of these
In a uniform magnetic field B, a wire in the form of a semicircle of radius r rotated about the diameter of the circle with angular frequency ‘ω’. The axis of rotation is perpendicular to the field. If the total resistance of the circuit is R the mean power generated per period of rotation is :
  • \(\frac{Bπr^2ω}{2R}\)
  • \(\frac{(Bπr^2ω)^2}{8R}\)
  • \(\frac{(Bπrω)^2}{2R}\)
  • \(\frac{(Bπrω^2)^2}{8R}\)
The role of inductance is equivalent to:
  • inertia
  • force
  • energy
  • momentum
A metal conductor of length 1 m rotates vertically about one of its ends at angular velocity 5 rad s-1. If the horizontal component of earth's magnetism is 2 × 10-5 T, then e.m.f. developed between the two ends of the conductor is:
  • 5 µV
  • 50 µV
  • 5 mV
  • 50 mV
coil of L = 8.4 mH and R = 6 Ω is connected to a 12 V battery. The current in the coil is 1.0 A at approx'time of:
  • 500 s
  • 20 s
  • 35 ms
  • 1 ms
If I current is flowing inductance L, then the dimension of \(\frac{3}{2}\) LI² is equivalent to:
  • charge
  • force
  • momentum
  • energy
The phase difference between the flux linkage and the emf in a rotating coil in a uniform magnetic field is:
  • zero
  • \(\frac{π}{2}\)
  • \(\frac{π}{4}\)
  • π
A choke is used as a resistance in :
  • dc circuits
  • ac circuits
  • both ac and dc circuits
  • neither (a) nor (b)
The SI unit of magnetic flux is:
  • T
  • Tn-2
  • Wb
  • Wb m-2
For purely capacitive circuits, power factor is:
  • 0
  • -1
  • 1
  • infinity
The magnetic flux linked with a coil is inversely proportional to the?
  • magnetic field
  • area of cross section
  • number of turns
  • none of these
0 h : 0 m : 1 s

Answered Not Answered Not Visited Correct : 0 Incorrect : 0