Multiple Choice Questions on Electrical Circuits -1

Important Multiple Choice Questions in Electrical Circuits

1.       The energy stored in the magnetic field at a solenoid 30 cm long and 3 cm diameter wound with 1000 turns of wire carrying a current at 10A, is

A)     0.015 Joule

B)      0.15 Joule

C)      0.5 Joule

D)     1.15 Joule

2.       For a transfer function H(s)= P(s)/Q(s), where P(s) and Q(s) are polynomials in s. Then

A)     The degree of P(s) is always greater than the degree of Q(s)

B)      The degree of P(s) and  Q(s) are same

C)      The degree of P(s) is independent of the  degree of Q(s)

D)     The maximum degree of P(s) and  Q(s) differ at most by one

3.       The resistance of a strip of copper of rectangular cross section is 2Ω. A metal of resistivity twice that of copper is coated on its upper surface to a thickness equal to that of copper strip. The resistance of composite strip will be

A)     6Ω

B)      4/3Ω

C)      3/2Ω

D)     3/4Ω

4.       The copper armature winding of a motor is subjected to an operating temperature of 80⁰ C. The room temperature is 20⁰C. The percentage change in resistance of the armature winding from cold starting condition to normal running will be nearly

A)     10%

B)      16%

C)      20%

D)     24%

5.       Two coils in differential connection have self inductance of 2 mH and 4 mH and a mutual inductance of 0.15 mH. The equivalent inductance of the combination is

A)     5.7 mH

B)      5.85 mH

C)      6 mH

D)     6.15 mH

6.       The current through an electrical conductor is 1A when the temperature of the conductor is 0⁰C and 0.7 A when the temperature is 100⁰C. The current when the temperature of the conductor is 1200⁰C must be

A)     0.08A

B)      0.16A

C)      0.32A

D)     0.64A

7.       The two windings of a transformer have an inductance of 2 H each. If the mutual inductance between them is also 2 H, then

A)     The transformer is an ideal transformer

B)      The turns ratio of the transformer is also two

C)      It is a perfect transformer

D)     None of these

8.       A choke coil having resistance R ohms and L henrys is shunted by a capacitor of C farads. The dynamic impedance of the resonant circuit would be

A)     R/LC

B)      C/RL

C)      L/RC

D)     1/RLC

9.       A two terminal black box contains one of the R,L,C elements. The black box is connected to a 220 V AC Supply. The current through the source is I. When a capacitance of 0.1 F is inserted in the series between the source and the box, the current through the source is 2I. The element is

A)     A resistance

B)      An inductance

C)      A capacitance of 0.5F

D)     Not possible to determine the element

10.   Two 2 H inductance coils are connected in series and are also magnetically coupled to each other. The coefficient of coupling being 0.1. the total inductance of the combination can be

A)     0.4 H

B)      3.2 H

C)      4.0 H

D)     3.6 H