CPCB Scientist B Paper | Central Pollution Control Board Scientist B Old Paper for Electrical Engineering

(Every Correct answer 1 mark, every wrong answer – 0.25 mark as a negative marking)

“1,000 watts per square meter solar irradiance, 1.5 Air Mass, 68 degrees Fahrenheit ambient temperature at 33 feet above ground level and wind speed of 1 meter per second” is the –
(a) STC Rating of solar panel
(b) PTC Rating of solar panel
(c) STC Rating of solar cell
(d) PTC Rating of solar cell

The most cost-effective & most energy efficient fluorescent lights, respectively, are-
(a) T-8 & T-12 lights
(b) T-12 & T-5 lights
(c) T-12 light
(d) T-8 & T-5 lights

A dc shunt generator is supplying a load of 2.6 kW at 200 V. Its armature and field resistances are 0.4 ohm and 100 ohm respectively. What is the generated emf?
(a) 190 V
(b) 206 V
(c) 204 V
(d) 210 V

What is the increase in the torque expressed as percentage of initial torque, if the current drawn by a d.c series motor is increased from 10 A toll A (Neglect saturation)?
(a) 21%
(b) 25%
(c) 41%
(d) 44%

A single-phase transformer when supplied from 220 V, 50 Hz has eddy current loss of 50 W. If the transformer is connected to a voltage of 440 V, 50 Hz, the eddy current loss will be
(a) 50 W
(b) 100 W
(c) 200 W
(d) 112.5 W

The rotor power output of 3-phase induction motor is 24kW. The rotor copper losses at a slip of 4% will be
(a) 960 W
(b) 1000 W
(c) 1040 W
(d) 1050 W

The supply voltage to an induction motor is reduced by 10%. By what percentage approximately, will the maximum torque decrease?
(a) 5%
(b) 10%
(c) 20%
(d) 40%

The rotor frequency of a 3-phase, 5kW, 400 V, 50 Hz, 4-pole slip ring induction motor is 5 Hz. The speed of the motor when connected to 300 volt, 50 Hz supply will be
(a) 1500 rpm
(b) 1000 rpm
(c) 1350 rpm
(d) zero

The rated slip of an induction motor at full-load is 10% while the ratio of starting current to full load current is four. The ratio of the starting torque toold full load torque would be
(a) 0.6
(b) 0.8
(c) 1.0
(d) 1.6

If the field of a synchronous motor is under-excited, the power factor will be
(a) Lagging
(b) Leading
(c) Unity
(d) More than unity

The charging reactance of 50 km length of the line is 1500 ohm. What is the charging reactance for 150 km length of the line?
(a) 1500 ohm
(b) 4500 ohm
(c) 500 ohm
(d) 3000 ohm

In an a.c series RLC circuit, the voltage across R and L is 20 V, voltage across L and C is 9 V and voltage across RLC is 15 V. What is the voltage across C?
(a) 7 V
(b) 12
(c) 16 V
(d) 21

When a lossless transmission line is terminated in its characteristic impedance.
(a) It behaves as an infinite line
(b) Its input impedance equals characteristic impedance
(c) Both a and b
(d) Neither A nor B

As the doping is increases, the resistance of a semiconductor –
(a) increases
(b) decreases
(c) remains the same
(d) none of the above

The energy-gap between conduction band and valence band of a substance is of the order of 0.07 eV. It is ______
(a) an insulator
(b) a semiconductor
(c) an alloy
(d) a conductor