Ques.11. Two coils have an inductance of 8 mH and 18 mH and a coefficient of coupling of 0.5. If the two coils are connected in series aiding, the total inductance will be (SSC-2017)

32 mH

38 mH

40 mH

48 mH

Answer.2. 38 mH

Explanation:

Total inductance is given as

Leq = L1 + L2 + 2M……………..1

Where M = K√L1L2

= 0.5√8 x 18

= 6

Putting the value of M in equation number 1

= 8 + 18 + 2 x 6

= 8 + 18 + 12

= 38 mH

Ques.12. As per Faraday’s Law of electromagnetic induction, an e.m.f is induced in a conductor whenever it (SSC-2017)

Lies perpendicular to the magnetic flux

Lies in a magnetic field

Cuts magnetic field

Move parallel to the direction of the magnetic field

Answer.3. Cuts magnetic field

Explanation:

Faraday’s Law of electromagnetic induction states that an emf s induced in the conductor whenever it cuts across the lines of force of a magnetic field.

Ques.13. Electrolyte capacitor has _________ tolerance Value. (SSC-2017)

Wide

Low

Zero

None of these

Answer.1. Wide

Explanation:

Electrolytic capacitors have a very wide tolerance. Often capacitors may be quoted as -20% and +80%. This is not normally a problem in applications such as decoupling or power supply smoothing, etc.

Ques.14. For 30 V, 5-ohm resistance if the current flowing is 6A, what will about the state of the fuse if resistance decreases. (SSC-2017)

Open

Short

Burts

No effect

</span Answer.1. Open

Explanation:

According to Ohm’s law if resistance decrease, while voltage is held at constant value than the current flow in the circuit will increase. This increase in the current may cause the fuse to trip because the combined current in the parallel device has exceeded the fuse safety limit. Therefore the fuse gets open.

Ques.15. Equivalent resistance and capacitance in case of the series combination (SSC-2017)

Increase, Decrease

Increase, Increase

Decrease, Decrease

Decrease, Increase

Answer.1. Increase, Decrease

Explanation:

In series combination the equivalent resistance is added up R1 + R2 = 2R

While in series combination the equivalent capacitance become 1/C1 + 1/C2 = C/2

Therefore for resistance the equivalent resistance increase and for capacitance equivalent capacitance decrease in the case of the series combination.

Ques.16. The specific resistance of a wire depends upon (SSC-2017)

Length

Cross-sectional area

Material

Temperature

Answer.4. Material

Explanation:

Specific Resistance

For any given material at a certain given temperature, the resistance is given as

where ρ is a constant depending on the nature of the material of the conductor and is known as its specific resistance or resistivity.

Specific Resistance depends only on temperature and material of the conductor but not on its dimensions of the conductor, on which resistance depends, and mechanical deformation such as stretching, etc. As ρ depends only on the material of a conductor at a given temperature, hence it is a characteristic constant.

Ques.18. A voltage source V_{AB} = 4 sin ωt is applied to the terminal A and B of the circuit shown in the given figure. The diodes are assumed to be ideal. The impedance offered by the circuit across the terminal A and B is (SSC-2017)

5 kΩ

10 kΩ

15 kΩ

20 kΩ

Answer.2. 10 KΩ

Explanation:

In the first half of the cycle, Diode D1 conducts and the impedance offered will be 10 KΩ as shown in the below figure

In the negative half cycle, diode D2 conducts and impedance offer will be 10 KΩ

Hence equivalent impedance offered across terminal A and B is 10 KΩ

Ques.19. Millman theorem is an extension of? (SSC-2017)

Norton

Thevenin

Superposition

Both 1 & 2

Answer.4. Both 1 & 2

Explanation: Millman’s theorem provides an equivalent circuit that is Similar to Thevenin or Norton equivalent circuit. Hence we can say that the Millman’s theorem is an extension of Thevenin’s or Norton’s theorem for the circuit containing the number of independent voltage or current source respectively.

Ques.20. A tank circuit of RF amplifier has a coil of Q factor of 100. It is tunned to a frequency of 1 MHz. The bandwidth of the circuit is (SSC-2017)