Prasar Bharti Assistant Engineers Examination : Solved Question Paper

Prasar Bharti (All India Radio) Examination 2011

Assistant Engineer Exam
Solved Question Paper with Answer

Q. Lamps used for street lighting are connected in

• parallel
• series and parallel both
• series
• none of the above

Q. A. C. can be measured with the help of:

• moving coil galvanometer
• hot wire ammeter
• tangent galvanometer
• galvanometer

Q.A p-n junction is said to be forward biased, when

• the positive pole of the battery is joined to the p-semiconductor and negative pole to the n-semiconductor
• the positive pole of the battery is joined to the n-semiconductor and negative pole of the
• battery is joined to the p-semiconductor
• the positive pole of the battery is connected to n- semiconductor and p- semiconductor
• a mechanical force is applied in the forward direction

Q. At absolute zero, Si acts as ?

• non-metal
• metal
• insulator
• none of these

Q. When N-type semiconductor is heated ?

• number of electrons increases while that of holes decreases
• number of holes increases while that of electrons decreases
• number of electrons and holes remain same
• number of electron and holes increases equally.

Q. Radiowaves of constant amplitude can be generated with

• FET
• filter
• rectifier
• oscillator

Q. In a common base amplifier the phase difference between the input signal voltage & the output voltage is ?

• 0
• pi/4
• pi/2
• p

Q. When a triode is used as an amplifier the phase difference between the input signal voltage and the output is ?

• 0
• pi
• pi/2
• pi/4

Q. The depletion layer in the P-N junction region is caused by?

• drift of holes
• diffusion of charge carriers
• migration of impurity ions
• drift of electrons

Q. The following truth table corresponds to which Logic gate
A    B    Output
0     0      0
0     1      1
1     0      1
1     1      1

• NAND
• OR
• AND
• XOR

Q. To use a transistor as an amplifier

• The emitter base junction is forward biased and the base collector junction is reversed biased
• no bias voltage is required
• both junction are forward biased
• both junctions are reversed biased.

Q. Which one of the following is the weakest kind of the bonding in solids

• ionic
• metallic
• Vander Walls
• covalent

Q. For amplification by a triode, the signal to be amplified is given to

• the cathode
• the grid
• the glass-envelope
• the anode

Q. A piece of copper and other of germanium are cooled from the room temperature to 80K, then

• resistance of each will increase
• resistance of copper will decrease
• the resistance of copper will increase while that of germanium will decrease
• the resistance of copper will decrease while that of germanium will increase

Q. Diamond is very hard because ?

• it is covalent solid
• it has large cohesive energy
• high melting point
• insoluble in all solvents

Q. The part of the transistor which is heavily doped to produce large number of majority carriers is

• emitter
• base
• collector
• any of the above depending upon the nature of transistor

Q. An Oscillator is nothing but an amplifier with

• positive, feedback
• negative feedback
• large gain
• no feedback

Q. When a P-N junction diode is reverse biased the flow of current across the junction is mainly due to

• diffusion of charge
• drift charges
• depends on the nature o material
• both drift and diffusion of charges

Q. Which of the following gates corresponds to the truth table given below?
A     B     Output
1     1        0
0     1        1
1     0        1
0     0        1

• NAND
• OR
• AND
• XOR

Q. Which of the following, when added as an impurity, into the silicon, produces n-type semi conductor

• Phosphorous
• Aluminium
• Magnesium
• None Of These

Q. The current gain for a transistor working as common-base amplifier is 0.96. If the emitter current is 7.2 mA, then the base current is

• 0.29mA
• 0.35mA
• 0.39 mA
• 0.43 mA

Q. When a n-p-n transistor is used as an amplifier then ?

• the electrons flow from emitter to collector
• the holes flow from emitter to collector
• the electrons flow from collector to emitter
• the electrons flow from battery to emitter

Q. When arsenic is added as an impurity to silicon, the resulting material is?

• n-type semiconductor
• p-type semiconductor
• n-type conductor
• Insulator

Q. To obtain a p-type germanium semiconductor,it must be doped with ?

• arsenic
• antimony
• indium
• phosphorus

Q. A semi-conducting device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops to almost zero. The device may be

• A p-n junction
• An intrinsic semi-conductor
• A p-type semi-conductor
• An n-type semi-conductor