BSNL JTO ELECTRICAL ENGINEERING SOLVED PAPER I

BSNL JTO 2009 EXAMINATION

ELECTRICAL ENGINEERING

SECTION-I

QUESTION NUMBER 1-20 CARRY 1 MARK EACH

Q.1.The main scale of a vernier calliper is ruled in 1 mm units. The vernier scale is 49 mm long
and divided in 50 units. The resolution of the vernier callipers is

• 0.002 mm 
• 0.005 mm 
• 0.01 mm 
• 0.02 mm

Q.2.A frequency counter with gating time of 50 ms counts 1254 cycles of an input square wave. The frequency of the input wave is

• 39.87 Hz 
• 62.70 Hz 
• 1.254 kHz 
• 25.08 kHz

Q.3.A data acquisition system with the input range of ± 5.0 V has a 12-bit ADC in it.The resolution of the system is approximately

• 0.24 mV 
• 0.48 mV 
• 1.22 mV 
• 2.44 mV

Q.4.Wattmeters are based on the principle of

• permanent magnet moving coil meter 
• electrodynamic meter 
• electrostatic meter 
• moving iron meter

Q.5.The resolution of a Gray-coded optical shaft encoder with 10-bit output is approximately

• 0.098° 
• 0.176° 
• 0.225° 
• 0.352

Q.6.If y(t) Y(s) indicates a Laplace transform pair, then y(t) for t>=0 when

 

Q.7..The un-damped natural frequency in rad/s and the damping ratio of the system with the transfer function are,respectively,

• 10 and 1.2
• 10 and 0.6
• 8 and 1.2
• 8 and 0.75

Q.8.The gain at the breakaway point of the root locus along the real axis of a unity feedback system with the transfer function 

• K = 0
• K = 0.5
• K = 1
• K = 1.25

Q.9.Gain margin of the unity feedback system with the loop transfer function 

• 35.35
• 12.5
• 0.08
• 0.03

10.The discrete time system with the transfer function

• stable
• unstable
• marginally stable
• sustained oscillatory

Q.11.The unit of the permittivity of free space is

• C^2 N–1 m–2
• C^2 N m2
• C^–2 N m2
• C^–2 N m–1

Q.12.A positively charged object is placed in the centre of a room with a uniform magnetic field. If the magnetic field is pointing east, the object will

• move east
• move north
• move south
• remain stationary

Q.13.The input impedance of a quarter-wave long short-circuited lossless transmission line is

• purely reactive
• purely resistive
• infinite
• dependent on the characteristic impedance of the line

Q.14.For a plane wave propagating in the free space

• the electric and magnetic fields are in parallel to the direction of propagation there is no field in the direction of propagation
• the electric and magnetic fields are out of phase
• the magnetic field amplitude is inversely proportional to the electric field amplitude
• None of these

Q.15.Which of the following materials has the largest energy gap between the conduction band and the valence band?

• Gold
• Silicon
• Doped germanium
• Porcelain

Q.16.The area of hysteresis loop in a ferromagnetic material is a measure of

• loss of energy
• loss of magnetic domain
• loss of magnetic dipole
• loss of eddy currents

Q.17.If a tetra-valent impurity is added to a pure silicon crystal at room temperature, it becomes

• a p-type semiconductor
• an n-type semiconductor
• an npn-type semiconductor.
• an insulator

Q.18.The circuit shown in Fig. I.18 has the following source values: VA = 600 t u(t+1) V, VB = 600(t+1) u(t) V and IC = 6 (t—1) u(t—1) A, where u(.) denotes the unit step function. For this circuit, the current i at t = –0.5s will be