Competitive Exams: Physics MCQs (Practice-Test 28 of 35)

  1. Twelve equal wires each of resistance 6 0 form a cube. The resistance between the two diagonally opposite comers will be

    1. 3 W

    2. 4 W

    3. 5 W

    4. 6 W

  2. The area of circular coil with 2000 turns is 10 cm2. Its place perpendicular to a magnetic field of 0.3 Wb/m2, is rotated by 180. The change in the magnetic flux is

    1. 1.2 Wb

    2. -1.2 Wb

    3. 0.6 Wb

    4. -0.6 Wb

  3. Ratio waves of wavelength 360 m are transmitted from a transmitter. The inductance of the coil which must be connected with a capacitor of capacity 1.2N F in a resonant circuit to receive these waves will be approximately.

    1. 103H

    2. 102 H

    3. l. 0 − 4 H

    4. 10 − 8H

  4. Which of the following Law illustrate the fact that the strength of the induced emf developed from a magnetic field depends upon the rate of change of magnetic flux or magnetic induction?

    1. Faraday's law of electromagnetic induction

    2. Lenz's law

    3. Newman's law

    Select the correct answer using the codes given below

    1. 1 alone

    2. 1, 2 and 3

    3. 2 and 3

    4. 1 and 3

  5. The natural frequency of a circuit containing a condenser, resistance and inductance, all in series, is given by Consider the following statements in this regard.

    1. When R2 > 4L/C the discharge is dead beat or non-oscillatory.

    2. When R2 = C the discharge is critically damped.

    3. When R2 < C, the discharge is oscillatory.

    Of these statements

    1. 1, 2 and 3 are correct

    2. 1 and 2 are correct

    3. 2 and 3 are correct

    4. 1 and 3 are correct

  6. Consider the following statements regarding ac circuit having an inductance and a capacitance

    1. Parallel resonance circuit is used for wireless reception.

    2. Parallel resonance circuit works as a perfect choke for ac and therefore is called a rejector.

    3. Series resonance circuits have special importance in transmission systems.

    4. It, series resonance circuit, current and emf are ire phase and hence called acceptor circuit.

    Of those statements

    1. 1, 2 and 4 are correct

    2. 2, 3 and 4 are correct

    3. 1 and 3 are correct

    4. 2 and 4 are correct

  7. Current in a coil of 1.5 H increases as I = 4 sin (2t) amperes. During the time the current changes from 0 to 4 A, the amount of energy spent will be

    1. 24 J

    2. 12J

    3. 8 J

    4. 6 J