Description : Depletion region of a junction is formed _________ (a) during the manufacturing process (b) under forward bias (c) under reverse bias (d) when temperature varies
Last Answer : (a) during the manufacturing process
Description : Consider the following statements regarding the formation of P-N junctions: 1. Holes diffuse across the junction from P-side to N-side 2. The depletion layer is wiped out. 3. There is continuous flow of current across the junction 4 ... correct? (a) 1 and 3 (b) 2 and 3 (c) 1 and 4 (d) 2 and 4
Last Answer : Ans: (c) When a pn-junction is formed, there will be diffusion of carries across the junctions followed by recombination, and the creation of a depletion layer across which a ... potential is established, which will prevent further diffusion of carries across the junction, leading to equilibrium
Description : Depletion region carries _________ (a) +ve charge (b) –ve charge (c) no charge (d) all of above
Last Answer : (c) no charge
Description : In forward bias, the width of potential barrier __________ (a) Increases (b) decreases (c) remains same (d) no effect
Last Answer : (b) decreases
Description : The potential barrier for germanium is _______ (a) 0.6 V (b) 0.2 V (c) 0.3 V (d) 0.5 V
Last Answer : (c) 0.3 V
Description : All electrical appliances are connected in parallel to each other between the main line and neutral wire to get a. same current b. same current and potential difference c. different current but same potential difference d. different current and potential differences
Last Answer : c. different current but same potential difference
Description : The central region of transistor is called (a) Base (b) emitter (c) collector (d) neutral
Last Answer : (b) emitter
Description : When the potential difference of 4 volt is applied across resistance, 10J energy is converted. Find the charge flows. a. 0.20 C b. 2.5C c. 5C d. 10C
Last Answer : b. 2.5C
Description : Define Depletion region and Barrier voltage of PN junction.
Last Answer : 1. Depletion region : The region consisting of immobile positive charge at n-side and immobile negative charge at p-side near the junction acts like a barrier and prevents the further flow of ... charge formed at the p-n junction is called barrier voltage, barrier potential or junction barrier.
Description : When a reverse bias is applied to a diode, it will a. Raise the potential barrier b. Lower the potential barrier c. Increases the majority-carrier a current greatly d. None of these
Last Answer : a. Raise the potential barrier
Description : Avalanche breakdown in a diode occurs when a. Potential barrier is reduced to zero. b. Forward current exceeds certain value. c. Reverse bias exceeds a certain value. d. None of these
Last Answer : c. Reverse bias exceeds a certain value.
Description : What is the difference between neutral and earth?
Last Answer : The ground or "earth" wire is a circuit's safety protective wire that normally carries no current.
Description : The time it takes a light induced carrier travel across the depletion region of the semiconductor. ∙ A. dispersion ∙ B. response time ∙ C. irradiance ∙ D. transit time
Last Answer : D. transit time
Description : The time it takes a light induced carrier travel across the depletion region of the semiconductor.
Last Answer : . transit time
Description : Barrier potential in a P-N junction is caused by (A) Thermally generated electrons and holes. (B) Diffusion of majority carriers across the junction. (C) Migration of minority carriers across the junction. (D) Flow of drift current.
Last Answer : (B) Diffusion of majority carriers across the junction.
Description : The reverse process of photo-electric effect is called: a) Annihilation of matter b) Compton effect c) Pair production d) X-rays
Last Answer : d) X-rays
Description : Process of conversion low voltage to high voltage is called _______ (a) Rectification (b)forward bias (c) reverse bias (d) amplification
Last Answer : (d) amplification
Description : Why ELCB cannot work if Neutral input of ELCB does not connect to ground?
Last Answer : ▪ ELCB is used to detect earth leakage fault. Once the phase and neutral are connected in an ELCB, the current will flow through phase and that same current will have to return neutral so ... that full fault current will come back through ELCB, and there will be no difference in current.
Description : What is a neutral?
Last Answer : In multiphase circuits, the conductor used to carry unbalanced current. In single-phase systems, the conductor used for a return current path.
Description : In liquids and gases the current is due to the motion a. negative charges b. positive charges c. both negative and positive charges d. neutral particles
Last Answer : c. both negative and positive charges
Description : The unit of absolute permittivity of a medium is
Last Answer : Farad/ metre
Description : Tick the wrong statement. a) Velocity of light is independent of the motion of the observer. b) Velocity of light in free space is the same in all directions. c) Velocity of light in free space is different in different directions. d) Absolute motion or absolute rest is meaningless to talk about
Last Answer : c) Velocity of light in free space is different in different directions
Description : The temperature at which material show super conductivity is a) Super temperature b) Critical temperature c)Kelvin temperature d)Absolute
Last Answer : d)Absolute
Description : The resistance of a conductor at absolute zero (OK) is a. zero almost b. infinite almost c. May increase or decrease d. None
Last Answer : zero almost
Description : How do you test reverse power trip, high current trip, preferential trip?
Last Answer : Reverse power trip - refer answer for question 11. Also ask E/O. High current (over load trip) - Set your overload relay high current trip setting to say 75% of the rated current. Run the ... loads to overload the generator. Preferential trip will trip all the non-critical loads. Also ask E/O.
Description : Why is this reverse power used instead of reverse current in alternators?
Last Answer : It is extremely difficult to detect reverse current with an alternating current system, reverse power can be detected and protection can be provided by reverse power relay.
Description : How do you test reverse power trip?
Last Answer : When two generators are running in parallel and one generator can carry the load, reverse power trip can be tested by load shifting using governor control. When the load has shifted sufficiently and the off ... (using the test push button on the relay) to see if it initiates a trip signal.
Description : How is the protection against reverse power given?
Last Answer : Reverse power protection is used for anti-motoring. This function is used for protection of prime mover not generator. It can cut-off the fuel supply and stop the prime mover.
Description : What is the harm if reverse power flows?
Last Answer : Assume that the generator normally produces an amount of power equal to P, and that when operating as a motor, it will absorb a similar amount, P. Therefore, the net effect on the grid will ... change on the grid. There could be prime mover damage in some instances (especially steam turbines).
Description : When does Reverse power flow?
Last Answer : Situation of a generator is feeding a system through switchgear having several generators connected in parallel with this generator. The flow of current, when the system is running normally, is from the ... minor to extreme in the event of a complete mechanical failure of the generator which fails.
Description : In the reverse biased p-n junction, the current is of the order of (a) Ampere (b) Milliampere (c) Microampere (d) Nano-ampere
Last Answer : (d) Nano-ampere
Description : On increasing the reverse bias to a large value in a p-n junction diode current (a) Increases slowly (b) Remains fixed (c) Suddenly increases (d) Decreases slowly
Last Answer : (c) Suddenly increases
Description : The reverse current through semiconductor diode is due to (a) Minority carrier (b) majority carrier (c) electrons (d) holes
Last Answer : (a) Minority carrier
Description : For normal operation of a transistor, the collector base junction is kept (a) Unbiased (b) forward biased (c) reverse biased (d) none
Last Answer : (c) reverse biased
Description : A multipurpose instrument for measuring current, potential difference and resistance is a) Ohmmeter b) Astatic galvanometer c) Rheostat d) AVO Meter
Last Answer : d) AVO Meter
Description : Terminal potential difference of a battery is greater than its emf when a. the internal resistance of battery is infinite b. the internal resistance of battery is zero c. the battery is charged d. the battery is discharged
Last Answer : c. the battery is charged
Description : Circuit which gives continuously varying potential is called a. complex network b. wheat stone bridge c. potential divider d. all of above
Last Answer : c. potential divider
Description : The force per unit charge is called: (a) Electric field (b) Electric field intensity (c) Electric potential energy (d) Electric potential
Last Answer : b) Electric field intensity
Description : Moving coil in dynamometer wattmeter connected a) In series with fixed coil b) Across supply c) In series with load d) Across load
Last Answer : Ans: Across supply
Description : A rod at rest appears to an observer just a mere point when he moves across it as speed, a) Equal to the speed of light b) Double the speed of light c) Three-fourth the speed of light d) None of the above
Last Answer : a) Equal to the speed of light
Description : A circuit which develops voltage across the horizontal deflection plates is known as a) Time base generator b) Electron gun c) Thermionic diode d) Zener diode
Last Answer : a) Time base generator
Description : Three bulbs are rating 40W 60W and 100W designed to work on 220V mains. Which bulb will burn most brightly if they are connected in series across 220 V mains? a. 40 W bulb b. 60 W blub c. 100 W blub d. all will burn equally brightly
Last Answer : a. 40 W bulb
Description : Three equal resistors connected in series with a source of e m f together dissipate 10 W of power each. What will be the power dissipated if the same resistors are connected in parallel across the same source of e m f? a. 40 W b. 90W c. 100W d. 120W
Last Answer : b. 90W
Description : When current of one ampere is flowing across any cross-section of wire in one second, then the quantity of charge is said to be: (a) One coulomb (b) Three coulomb (c) One micro-coulomb (d) None of above
Last Answer : (a) One coulomb
Description : Which series lies in the Ultraviolet region? a) Lyman series b) Paschen series c) Brackett serie d) Balmer series
Last Answer : a) Lyman series
Description : Three spectral series, paschen series, Brackett series, Pfund series are found in the a) ultraviolet region b) visible region c) infrared region d) a & b region
Last Answer : c) infrared region
Description : The region where the Lyman series contains the wavelength 1∕ λ = RH [1/ 12 – 1/ n2 ] is a) visible region b) infrared region c) ultraviolet region d ) none of these
Last Answer : c) ultraviolet region
Description : The only series which lies in the visible region of the electromagnetic spectrum is a) Paschen series b) Lyman series c) Balmer series d) Pfund series
Last Answer : b) Lyman series
Description : The radiations emitted by human body lies in a) Infrared region b) Ultraviolet region c) Visible region d) None of the above
Last Answer : a) Infrared region
Description : In transistor, the base region is of the order of _______ (a) 10-5 m (b) 10-2 m (c) 10-8 m (d) 10-6 m
Last Answer : d) 10-6 m