Bharat Electronics Limited (BEL) Question Bank continued from Part 4…
Source : www.bel-india.com
Q-29. If the gain of the amplifier is A and voltage feedback is fraction B of the amplifier output voltage, what will be the condition for maintenance of oscillation?
A : The condition for maintenance of oscillation would be AB = 1.
Q-30. State the condition for a RC high pass circuit.
A : For high pass RC circuit, the value of RC << t.
Q-31. What do you mean by an inverter?
A : Inverter is an equipment for transforming DC to AC.
Q-32. What is peak inverse voltage?
A : The voltage at which the electron flow starts from the anode is called peak inverse voltage.
Q-33. Why is the heater filament of a vacuum tube usually supplied with AC voltage and not DC voltage for heating?
A : That is because it is very easy to obtain AC voltage from AC power mains.
Q-34. What is the correct relation between Alpha and Beta of a transistor?
A : The relation is, β = α / 1-α.
Q-35. Name a device that uses avalanche breakdown?
A : UJT (Uni-Junction Transistor) which is also known as voltage-controlled oscillator uses avalanche breakdown.
Q-36. What is the effect of negative feedback in amplifier?
A : Negative feedback results in reduced gain and increased bandwidth.
Q-37. What do you mean by frequency response of a system?
A : Frequency response of a system is the range of frequencies between the upper and lower 3 dB points.
Q-38. How is light emitted in LED (Light Emitting Diode)?
A : Light in LED is emitted when recombination of charges take place.
Q-39. Why are N channel FETs superior to P channel FETs?
A : N channel FETs are superior because mobility of electrons is greater than that of holes.
Q-40. What is pinch off voltage?
A : In a Field Effect Transistor (FET), the drain voltage above which there is no increase in the drain current is called pinch off voltage.
Gautam Vashisht