Engineering Services Exam Sample Paper
1. The electric field lines and equipotential lines
(a) are parallel to each other
(b) are one and the same
(c) cut each other orthogonally
(d) can be inclined to each other at any angle
2. Consider the following statements ;
A current I flows through a circular coil of one turn of radius R in the counter-clockwise direction.
1. The magnetic field at the centre is inversely proportional to R.
2. The magnetic moment of the coil is directly proportional to R2
3. The magnetic field at its centre is directly proportional to R2.
Which of the above statements is/are correct ?
(b) 1 only
(c) 2 and 3
(d) 3 only
3. The depth of penetration of a wave in a lossy dielectric medium increases with
(a) Increasing wavelength
(b) Increasing conductivity
(c) Decreasing wavelength
(d) Increasing permittivity
4. Consider the following statements associated with the basic electrostatic properties of ideal conductors :
1. The resultant field inside is zero.
2. The net charge density in the interior is zero.
3. Any net charges reside on the surface.
4. The surface is always equipotential.
5. The field just outside is zero.
Which of the above statements are correct ?
(a) 1, 2,3 and 4
(c) 1, 2 and 3 only
5. In practice, Earth is chosen as a place of zero electric potential because it
(a) is non-conducting
(b) is easily available reference
(c) keeps losing and gaining electric charge everyday
(d) has almost constant potential
6. When the wave travels in a conducting medium, the rate of attenuation is decided by
(a) Attenuation constant
(b) Phase constant
(c) Both attenuation constant and phase constant
(d) Neither attenuation constant nor phase constant
7. Uniform plane wave is
(a) Longitudinal in nature
(b) Transverse in nature
(c) Neither longitudinal nor transverse in nature
8. The impedance Z offered by transmission line for a travelling wave which damps out the low frequency oscillation rapidly is also called
(a) Surge impedance
(b) Natural impedance
(c) Both surge and natural impedances
(d) Neither surge nor natural impedance
9. In a coaxial transmission line, the useful power flows through
(a) the interface of the two conductors
(b) both inner and outer conductors
(c) inner conductor
(d) outer conductor
10. A semiconductor device made out of a material having very high temperature coefficient of resistance is
11. The electrical conductivity of a semiconductor increases with increase in temperature because
(a) the carrier concentration increases
(b) the mobility of carrier increases
(c) both carrier concentration and mobility increase
(d) the band gap decreases
12. Which of the following are associated with soft superconductors ?
1. Silsbee's rule
2. Meissner effect
3. Faraday rotation
4. Curie-Weiss law
(b) 1 and 3 only
(c) 1 and 2 only
(d) 2 and 3 only
13. Materials, whose resistivity at very low temperatures plunges from a finite value to zero and remains there upon further cooling, are known as
(a) Ferromagnetic materials
(b) High-energy hard magnetic materials
(d) Ferrimagnetic materials
14. In a superconductor, if the temperature is decreased below its critical temperature, the value of critical magnetic field will
(c) Not change
(d) Increase or decrease depending on the superconductor material
15. The imaginary part of dielectric constant determines
(a) Component of current which is in phase with the applied field
(b) Component of energy absorbed per m3
(c) Amount of applied field
(d) Component of voltage which is in phase with the applied field
16. Manganese ferrite is a 1 : 1 mixture of
(a) Manganese nitride and iron oxide
(b) Manganese oxide and iron oxide
(c) Manganese nitride and iron sulphide
(d) Manganese oxide and iron sulphide
17. When a ferromagnetic substance is magnetized, small changes in dimensions occur. Such a phenomenon is known as
(a) Magnetic hysteresis
(b) Magnetic expansion
18. In ferromagnetic, anti-ferromagnetic and ferrimagnetic materials, the atomic thermal motions counteract the coupling forces between the adjacent atomic dipole moments, thereby causing
(a) Some dipole misalignment regardless of whether an external field is present
(b) Increase in dipole alignment regardless of whether an external field is present
(c) No effect on dipole alignment
(d) Atoms tend to de-randomize the direction of moments
19.The Hall Effect voltage in intrinsic silicon
(a) is positive
(b) is zero
(c) is negative
(d) changes its sign based on application of magnetic field
20. Most outstanding property of indium antimonide is
(a) A very wide range gap
(b) High resistivity at room temperature
(c) High carrier mobility
(d) Very low conductivity at room temperature
21. Which of the following semiconducting compounds is used in photoconductive devices ?
(a) Caesium antimonide
(b) Barium oxide
(c) Lead sulphide
(d) Zinc oxide
22. A magnetic ring has a mean circumference of 20 cm and a cross-section of 20 cm2 and has 800 numbers of turns of wire. When the exciting current is 5 A, the flux is 2 mWb. The relative permeability of iron is nearly
23. For a series R-C circuit, the power factor corresponding to maximum power is
(a) 0.5 lag
(b) 0.5 lead
(c) 0.707 lag
(d) 0.707 lead
24. The power consumed by a coil is 300 W when connected to a 30 V dc source and 108 W when connected to a 30 V ac source. The reactance of the coil is
(b) 4 0
25. A conductor of diameter d, length 1 consumes a power of W when a current I flows through it. What will be the power consumed if d is doubled, 1 is halved and current is tripled ?
(a) 18 W
(b) 36 W
(c) 48 W
(d) 72 W
26. When a source is delivering maximum power to a load, the efficiency of the circuit is always
(d) Depends on the circuit parameters
27. Consider the following statements :
Any element connected in
1. Series with an ideal current source is redundant.
2.Parallel with an ideal current source is redundant.
3. Series with an ideal voltage source is redundant.
4. Parallel with an ideal voltage source is redundant.
Which of the above statements is/are correct
(a) 1 only
(c) 2 only
(d) 1 and 4
28. The output power of a filter is 100 mW, when the signal frequency is 5 kHz. When the frequency is increased to 25 kHz, the output power falls to 50 mW. What is the dB change in power ?
(a) - 3 dB
(b) - 5 dB
(d) - 2 dB
29. The principle of operation used in capacitive transducers to measure level of liquid is change of
(a) Area of plates
(b) Dielectric strength
(c) Distance between plates
(d) Shape of plates
30. In any network the current will be seen to be consisting of a forced current and a natural current. A forced current is
(a) A steady-state current with external source but a natural current is a transient current in a closed circuit with no external source.
(b) A transient current with external source but a natural current is a steady-state current in a closed circuit with no external source.
(c) A steady-state current in a closed circuit without external source, while a natural current is a transient current with an external source.
(d) A transient current in a closed circuit without external source, while a natural current is a steady-state current with an external source.
31. A coil of resistance 10 S and inductance 0.8 H is connected to a 200 V dc supply. The initial rate of change of current is
(a) 16 A/s
(b) 160 A/s
(c) 250 A/s
(d) 4000 A/s
32. There are no transients in pure resistance circuits because they
(a) Offer high resistance
(b) Obey Ohm's law
(c) Have no stored energy
(d) Are linear circuits
33. A single-phase ac voltage source has 200 V rms and a system connected consumes an active power of 300 W. What is the reactive power consumed by the system if 2.5 A rms current is drawn ?
(a) 100 VAR
(b) 200 VAR
(c) 300 VAR
(d) 400 VAR
34. In a series resonant circuit, maximum voltage across L occurs at
(a) Resonant frequency
(b) Slightly below resonant frequency
(c) Slightly above resonant frequency
(d) At a frequency where I is maximum
35. Two wattmeters are used to measure the power in a'3-phase balanced system. What is the power factor of the load when one wattmeter reads twice the other ?
36. In a balanced 3-phase 200 V circuit, the line current is 115.5 A. When the power is measured by two wattmeter method, one of the wattmeters reads 20 kW and the other one reads zero. What is the power factor of the load ?
37. A coil having an inductance of 0.5 H and a resistance of 60 Sl is connected in series with a capacitance of 10 µF. The coil is connectedto 100 V ac supply. What is the source frequency and current flowing in the circuit under resonance condition ?
(a) 7.121 Hz and 16.7 A
(b) 7.121 Hz and 1.67 A
(c) 71.21 Hz and 16.7 A
(d) 71.21 Hz and 1.67 A
38. Three equal impedances are first connected in delta across a 3-phase balanced supply. If the same impedances are connected in star across the same supply then,
(a) Phase current will be one-third
(b) Line current will be one-third
(c) Power consumed will be one-third
(d) Phase current will remain the same
39. A Hurwitz polynomial D(s) must satisfy two conditions. One is the polynomial is real when s is real. What is the other condition ?
(a) Roots of D(s) have real parts which are positive and non-zero
(b) Roots of D(s) have imaginary parts which are negative
(c) Roots of D(s) have real parts which are either zero or negative
(d) Roots of D(s) have real parts which are positive or zero
40.In an induction type energy meter, the steady speed attained by the rotating disc is
1. Proportional to the deflecting torque.
2. Proportional to the resistance of the path of eddy currents.
3. Inversely proportional to the effective readings of disc from its axis.
4. Inversely proportional to the square of brake magnet flux.
Which of the above are correct ?
(a) 1,2 and 3 only
(b) 1,2 and 4 only
(c) 2,3 and 4 only
(d) 1,2,3 and 4