# Network Theory 6

Electronic Engineering MCQ Question Papers: ENTC, IT Interview Placement

Subject:  Network Theory 6

Part 6: List for questions and answers of Network Theory

Q1. If the iron core of a coil is removed so that it becomes an air cored coil, its inductance

a) Will increase

b) Will decrease

c) Will remain the same

d) May increase or decrease

Q2. A square current wave of magnitude 1 A is applied to an element for 5 seconds. The voltage across the element rises linearly from 0 to final value linearly. The element is

a) Resistance

b) Inductance

c) Capacitance

d) R and C in series

Q3. A periodic voltage v(t) = 1 + 4 sin wt + 2 cos wt is applied across a 1 ohm resistance. The power dissipated is

a) 1 W

b) 11 W

c) 21 W

d) 24.5 W

Q4. A coil is wound having a diameter d. Its inductance is 10 mH. If it is rewound on the same core with a wire having diameter 0.5 d and total weight of the wire is the same as before, the inductance will be

a) 5 mH

b) 10 mH

c) 160 mH

d) 40 mH

Q5. Permeability is analogous to

a) Conductivity

b) Resistivity

c) Retentivity

d) Coercivity

Q6. A 10 uF capacitor is charged from a 5 volt source through a resistance of 10 k ohm. The charging current offer 35 m sec. If the initial voltage on C is – 3 V is

a) 0.56 mA

b) 5.6 mA

c) 6 mA

d) 5 uA

Q7. If an admittance Y(s) has a term Ks, the realization would give

a) An inductance of value K

b) A resistance of value K

c) A capacitance of value K

d) Either (a) or(c)

Q8. If the diameter of a wire is doubled, the current carrying capacity of the wire becomes

a) Half

b) Twice

c) Four times

d) One-fourth

Q9. Two voltages 50 V each have a phase difference of 45°. The rms value of resultant sum of the two voltages is

a) 70.7 V

b) 80.4 V

c) 92.4 V

d) 100 V

Q10. The energy stored in a coil is 108 J. It is opened suddenly in 10 ms. The power dissipated instantaneously across the blades of switch is

a) 108 W

b) 1080 W

c) 10800 W

d) 108000 W

Q11. A magnetic circuit has an iron length of 20 cm and air gap length 0.1 cm. If uf = 200 then

a) mmf for iron and air gap are equal

b) mmf for iron is much less than that for air gap

c) mmf for iron is much more than that for air gap

d) either (a) or (c)

Q12. Two coils X and Y have self inductances of 5 mH and 10 mH and mutual inductance of 3 mH. If the current in coils X change at a steady rate of 100 A/s, the emf induced in coil Y is

a) 0.3 V

b) 0.5 V

c) 1 V

d) 1.5 V

Q13. Two capacitors of 2 uF and 4 uF capacitance are connected in series across a 30 V dc battery. After the capacitors have been charged, the voltage across them will be

a) 15 V each

b) 10 V and 20 V

c) 20 V and 10 V

d) 30 V each

Q14. A 50 Hz current has an amplitude of 10 A. The rate of change of current at t = 0.005 after i = 0 and is increasing is

a) 2221.44 A/s

b) 0

c) 2221.44 A/s

d) 3141.6 A/s

Q15. An RLC series circuit is fed form 100 V ac supply. Inductance is 1 H and Q = 7.5. At resonance, the voltage across inductance is

a) 750 V

b) 100 V

d) 1500 V

Q16. As temperature increases, the temperature coefficient of a metal

a) Decreases

b) Increases

c) Remains unchanged

d) Any of the above

Q17. A wire has a resistance R ohm. If another wire of the same material and same weight has double the diameter (as compared to the first wire), the resistance of the second wire will be

a) 0.5 R

b) 0.25 R

c) 0.125 R

d) R/16

Q18. Volt is equivalent to

a) Joule/coulomb

b) Joule/watt

c) Joule/ampere

d) Joule/volt

Q19. A two branch parallel tuned circuit has a capacitance C in one of the two branches and resistance R in second branchs. As C is decreased the dynamic resistance

a) Increases

b) Decreases

c) Remains constant

d) May increases or decreases

Q20. In an R-C circuit, the impedance is 40 ohm  at a frequency of 100 Hz. At 200 Hz the impedance should be

a) 40 ohm

b) 80 ohm

c) 20 ohm

d) More than 20 ohm but less than 40 ohm

Part 6: List for questions and answers of Network Theory