Quotes Of the day

Quotes of the day 

MCQ ON TRANSISTOR BIASING

BASICS ON TRANSISTOR BIASING 

1. Transistor biasing represents ……………. conditions

1. a.c. 

2. d.c. 

3. both a.c. and d.c. 

4. none of the above 

Ans : 2 

2. Transistor biasing is done to keep ………… in the circuit 

Proper direct current 

Proper alternating current 

The base current small 

Collector current small 

Ans : 1 

3. Operating point represents ………….. Values of IC and VCE when signal is applied 

The magnitude of signal 

Zero signal values of IC and VCE 

None of the above 

Ans : 3 

4. If biasing is not done in an amplifier circuit, it results in …………… 

Decrease in the base current 

Unfaithful amplification 

Excessive collector bias 

None of the above 

Ans : 2 

5. Transistor biasing is generally provided by a ……………. Biasing circuit 

Bias battery 

Diode 

None of the above 

Ans : 1 

6. For faithful amplification by a transistor circuit, the value of VBE 

should ………. for a silicon transistor 

Be zero 

Be 0.01 V 

Not fall below 0.7 V 

Be between 0 V and 0.1 V 

Ans : 3 

7. For proper operation of the transistor, its collector should 

have …………

 Proper forward bias 

Proper reverse bias 

Very small size 

None of the above 

Ans : 2 

8. For faithful amplification by a transistor circuit, the value of VCE 

should ……….. for silicon transistor 

Not fall below 1 V 

Be zero 

Be 0.2 V 

None of the above 

Ans : 1 

9. The circuit that provides the best stabilization of operating point 

is ………… 

Base resistor bias 

Collector feedback bias 

Potential divider bias 

None of the above 

Ans : 3 

10. The point of intersection of d.c. and a.c. load lines 

represents ………….. Operating point 

Current gain 

Voltage gain 

None of the above 

Ans : 1 

11. An ideal value of stability factor is ………….. 100 

200 

More than 200 

1 

Ans : 4 

12. The zero signal IC is generally ……………… mA in the initial stages 

of a transistor amplifier 

4 

1 

3 

More than 10 

Ans : 2 

13. If the maximum collector current due to signal alone is 3 mA, then 

zero signal collector current should be at least equal to ……….. 6 mA 

mA 

3 mA 

1 mA 

Ans : 3 

14. The disadvantage of base resistor method of transistor biasing is 

that it …………

Is complicated 

Is sensitive to changes in ß 

Provides high stability 

None of the above 

Ans : 2 

15. The biasing circuit has a stability factor of 50. If due to 

temperature change, ICBO changes by 1 µA, then IC will change 

by ………… 

100 µA 

25 µA 

20 µA 

50 µA 

Ans : 4 

16. For good stabilsation in voltage divider bias, the current I1 flowing 

through R1 and R2 should be equal to or greater than 

10 IB 

3 IB 

2 IB 

4 IB 

Ans : 1 

17. The leakage current in a silicon transistor is about ………… the 

leakage current in a germanium transistor 

One hundredth 

One tenth 

One thousandth 

One millionth 

Ans : 3 

18. The operating point is also called the …………. Cut off point 

Quiescent point 

Saturation point 

None of the above 

Ans : 2 

19. For proper amplification by a transistor circuit, the operating 

point should be located at the ………….. of the d.c. load line 

The end point 

Middle 

The maximum current point 

None of the above 

Ans : 2 

20. The operating point ………………… on the a.c. load line 

Also line 

Does not lie 

May or may not lie 

Data insufficient 

Ans : 1 

21. The disadvantage of voltage divider bias is that it has …………. High stability factor 

Low base current

 Many resistors 

None of the above 

Ans : 3 

22. Thermal runaway occurs when ………. Collector is reverse biased 

Transistor is not biased 

Emitter is forward biased 

Junction capacitance is high 

Ans : 2 

23. The purpose of resistance in the emitter circuit of a transistor 

amplifier is to …………. Limit the maximum emitter current 

Provide base-emitter bias 

Limit the change in emitter current 

None of the above 

Ans : 3 

24. In a transistor amplifier circuit VCE = VCB + …………….. VBE 

2VBE 

5 VBE 

None of the above 

Ans : 1 

25. The base resistor method is generally used in ……… 

Amplifier circuits 

Switching circuits 

Rectifier circuits 

None of the above 

Ans : 2 

Latest Discoveries in Electrical

Cell-sized Batteries:

These microbatteries could be only half the size of a human cell. Interestingly, these would be made of viruses. This rare innovation is set to provide us a relief from heavy 9-volts batteries and other models. This technology involves the use of microcontact printing. This printing fabricates and position microbattery electrodes. Further, it is probably the first use of virus in this field. These batteries could be used in a series of fields such as computers, cell phones and medical equipments which are implantable.

 Detection Systems Based on Quantum-entanglement Effect:

Entanglement, a unique feature of quantum physics, is well set to be used in future detection and imaging systems. It is said to be more efficient and accurate than those of many detection system available these days. This mechanism could work spreading entangled beams of light on any object. This could make a very detailed, fair and accurate image of the object being detected. This mechanism is supposed to work on the same principle which is applied to detect planes at airforce stations and airports.

 Precise Pattern Micro-chip:

This innovation is supposed to bring microchip technology at its peak. This system works when some molecules are made to assemble themselves into precise patterns. A self-assembling molecular system which is called block copolymers was known for many years. This system was not very effective as it could produce a molecular-orders or patterns in a very limited way via self-assembling. Thus to make it more equipped and advanced, this "limited self-assembly" was made to combine with conventional lithographic chip-making technology. These lithographic patterns cause a tight-hold over self-assembling molecules. Thus they become more structured.

Dielectric Susceptibility of a Material:

The finding of the dielectric susceptibility has provided enough chances to the engineers to make some ultra-equipped and highly sensitive technological and electronic devices. This discovery is a result of the effect of electric field on a nanostructure of lead zirconate. This specific feature of any material is supposed to be a boon for nanostructures. The importance of this innovation has been widely hailed as it has opened up many doors of making tiny but effective electronic devices.

 High-Power Solar Concentrators:

As the initial research has proved to be fruitful, there are chances that in coming years we will see a sort of solar concentrator, which would be more efficient than the contemporary solar concentrators. The most striking part of this innovation is that it brings huge amount of solar light to the solar cells that too without tracking the sun. Though it showed only 92 percent of stability during the research, it is supposed to guarantee a 100 percent stability till it arrives in the market.

Source: Electrical Learners

Some basic facts about Electricity

Some basic facts an Electrical Engineer should know..!🔋🔋🔋⬇️⬇️⬇️⬇️

1. You need to know Ohm's law V=IR, current is proportional to the voltage applied.

2. Electric shock is caused by current and not voltage. 30mA of current is enough to cause ventricular fibrillation in your heart.

3. Megger  is the name of a company. (Many people term measuring of Insulation resistance as Megger)

4. 'Exd' type equipments (sometimes called explosion proof) do not prevent explosion. They just help to isolate an explosion in the interior of the equipment from spreading outside.

5. Test before Touch. This is a mantra that every electrical engineer should remember. You need to check that there is no voltage before touching any live part. It may have been fed from a different source.

6. Nowadays, domestic fan regulators do not work on potential divider concept and there is no power loss if you operate the fan at lower/higher speeds.

7. System earthing and body earthing are different.

8. All motors are treated in kW/MW, transformers in MVA/kVA and fuses in A.

9. 'k' in kW, kVA, kA, kV need to be in smaller case and not as in KW, KVA, KA, KV.

10. Incidents can happen anytime and one should wear appropriate safety gear before working on an electrical installation.

11. In electrical cables, size of the core determines the amount of current it can carry and the thickness of Insulation determines the voltage level it can work at.

12. Making capacity of a circuit breaker is approximately 2.5 times its breaking capacity.

13. In transformers, Dyn11 vector group will become Yd1 if you change its primary and secondary sides.

14. Neutral is solidly grounded in the 415V system at the user end to protect people from shock.

15. 230V, that we measure is the rms value and the actual peak AC voltage is √2 * 230V.

16. Every electrical engineer should know how to give basic first aid and CPR. CPR can bring a dead person to life.

17. Zero watt bulbs available in the market are not actually rated for zero watt. Their ratings vary from 5W to 20W.