Defence Research and Development Organisation (DRDO) electrical exam question papers

Can you please provide me Defence Research and Development Organisation (DRDO) electrical exam question papers?

[Kiran Chandar]

Here I am providing you Defence Research and Development Organisation (DRDO) electrical exam question papers.

Q.1:- 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

Q.2:- 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.

Q.3:- For an SCR, di/dt protection is achieved through the use of
(a) R in series with SCR.
(b) L in series with SCR.
(a) RL in series with SCR.
(c) RLC in series with SCR.

Q.4:- In a linear system, an input of 5 sin wt produces an output of 10 cos wt. The output
corresponding to input 10 cos wt will be equal to
(a) + 5 sin wt (b) - 5 sin wt (c) + 20 sin wt (d) – 20 sin wt.

Q.5:- For the system shown in figure, with a damping ratio § of 0.7 and an undamped natural
frequency wof 4 rad / sec, the values of K and are
(a) K = 4, a = 0.35
(b) K = 8, a = 0.455
(c) K = 16, a = 0.225
(d) K = 64, 0.9

Q.6:- A single instruction to clear the lower four bits of the accumulator I 8085 assembly language is:
(a) XRI OHF (b) ANI FOH (c) XRI FOH (d) ANI OFH.

Q.7:- The p-type substrates in a conventional pn-junction isolated integrated circuit should be
connected to:
(a) Nowhere, i.e., left floating.
(b) A dc ground potential.
(c) The most positive potential available in the circuit.
(d) The most negative potential available in the circuit.

Q.8:- The velocity of electromagnetic ratio waves is
(a) 3 x
(b) 3 x
(c) 3 x
(d) 3 x

Q.9:- A certain 8- bit microprocessor executes “SUB A, B” by loading B to the ALU, then loading A to
the ALU, Subtracting A from B, and storing the result in B. Which of the following instructions would
cause the ZERO flag to be set?
(a) SUB – (X), (X) +
(b) SUB )X), (X) +
(c) SUB – ( X), (X)
(d) all of the above

Q.10:- which of the following induction motor will have the least shaft diameter?
(a) 20 HP, 2880 rpm
(b) 20 HP, 1440 rpm
(c) 20 HP, 960 rpm
(d) 20 HP, 730 rpm

Q.11:- In ‘plasma’ state a gas
(a) ( a) loses electrical conductivity
(b) ( b) attracts moisture
(c) ( c) becomes perfect dielectric medium
(d) ( d) conducts electricity

Q.12:- If the secondary winding of the ideal transformer shown in the figure below, has 40 turns, the
number of turns in the primary winding for maximum power transfer to the 2 ohm resistor will be
IDEA TRANSFORMER
( a) 20 (b) 40 (c) 80 (d) 160

Q.13:- A 6 pole 3-phase wound-rotor induction machine is driven by another machine at 1800 rpm.
The rotor of the induction machine is connected to a 50Hz system. If the mechanical rotation of the
rotor is in the same direction as the rotor winding flux rotation, then frequency of the stator voltage
will be
(a) 50Hz (b) 140 Hz (c) 150 Hz (d) 200 Hz

Q.14:- A universal motor runs at
(a) Higher speed will dc supply and with less sparking.
(b) Higher speed with ac supply with less sparking.
(c) Same speed both ac and dc supplies.
(d) Higher speed with ac supply but with increased sparking at the brushes.

Q.15:- Two 550 kVA alternator operate in parallel to supply the following loads
I. 250 KW at 0.95 p.f. lagging
II. 100 KW at 0.85 p.f. leading
One machine is supplying 200 KW at 0.9 p.f. lagging. The p.f. of other machine must be
(a) 0.89 leading (b) 0.95 leading (c) 0.95 lagging (d) 0.89 lagging

Q.16:- In a 110 volts compound generator, the armature, shunt and series windings are 0.06 ohm,
27.5 ohm and 0.04 ohm respectively. The load consists of 200 lamps; each rated at 55 W, 110 V. find
the total e.m.f. when the machine is conne
cted for long shunt operation.
(a) 12 V (b) 72 V (c) 100 V (d) 120 V
Q.17:- 1 Bagasse is
(a) Low quality coal.
(b) A fuel consisting of wood.
(c) Fibrous portion of sugarcane left after extracting the juice.
(d) A kind of rice straw.

Q.18:- The copper armature winding of a motor is subjected to an operating temperature of 80°C.
The room temperature is 20° C. The percentage change in resistance of the armature winding from
cold staring condition to normal running will be nearly:
(a) 10% (b) 16% (c) 20% (d) 24%

Q.19:- Magnetic flux density at a point distance R due to an infinitely long linear conductor carrying a
current is given by
(a) B = (b) B =
(c) B = (d) B =

Q.20:- A zener diode works on the principle of
(a) Tunneling of charge carriers across the junction.
(b) Thermionic emission.
(c) Diffusion of charge carriers across the junction.
(d) Hoping of charge carriers across the junction.

Q.21:- Two resistance 100Ω ± 5Ω ± 15Ω are connected in series. If the errors are specified as standard
deviations, the resultant error will be
(a) ± 10Ω (b) ± 10.6Ω (c) ± 15.8Ω (d) ± 20Ω

Q.22:- The unit impulse response of a system is given as c (t) = +6e−2t. The step response of the same
system for ≥0 is equal to
(a) − 3e−2t +4e−t+1
(b) −3e−2t +4e−t−1
(c) −3e−2t +4e−t −1
(d) 3e−2t +4e−t −1

Q.23:- Which of the following statements is true?
(a) ROM is a Read/Write memory.
(b) PC points to the last instruction that was executed.
(c) Stack works on the principal of LIFO.
(d) All instructions affect the flags.

Q.24:- If a transistor is operation with both of its junctions forward biased, but with the collector
forward bias greater than the emitter-base forward bias, then it is operating in ht
(a) Forward active mode.
(b) Reverse saturation mode.
(c) Reverse active mode forward saturation mode.
(d) Forward saturation mode.

Q.25:- Which type of transmission line will have the maximum value of characteristic impedance?
(a) Open wire line.
(b) Twin lead line.
(c) Coaxial cable.
(d) All have same impedance.

Q.26:- The ALU of a microprocessor performs operations of8-bit two’s complement operands. What
happens the operation 7A ₁₆ – A2₁₆ is performed?
(a) Result = D8₁₆’Overflow and negative flags set.
(b) Result = D8₁₆’ Negative flag is set.
(c) Result = D8₁₆’No flags set.
(d) Result = 28₁₆’overflow flag set.

Q.27:- Efficiency of a plant is secondary consideration for
(a) Base load power plants.
(b) Peak load power plants.
(c) Both peak loads as well as base load power plants.
(d) Neither peak load nor base load power plants.

Q.28:- An undesirable side effect of motional inductance of large conduction specimens is
(a) Skin effect (b) hysteresis (c) eddy currents (c) dielectric loss

Q.29:- if the rated voltage from the power lines is applied to the primary of a single-phase
transformer which is operated on no-load, then
(a) Both input voltage and current are sinusoidal.
(b) Both input voltage and current are non-sinusoidal.
(c) Input voltage is non-sinusoidal and input current sinusoidal.
(a) D input voltage is sinusoidal and input current is non sinusoidal.

Q.30:- “In all cases of electromagnetic induction, an induced voltage will cause a current to flow in a
closed circuit in such a direction that the magnetic field which is caused by that current will oppose
the change that produces the current” is the original statement of
(a) Lenz’s law
(b) Faraday’s law of magnetic induction.
(c) Fleming’s law of induction
(d) Ampere’s law

Q.31:- The sator and rotor pole number may be different in a
(a) Pole changing induction motor.
(b) Reluctance motor.
(c) Repulsion motor.
(d) Synchronous motor.

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