Advertisements
Advertisements
प्रश्न
When an electric field is applied across a semiconductor ______.
- electrons move from lower energy level to higher energy level in the conduction band.
- electrons move from higher energy level to lower energy level in the conduction band.
- holes in the valence band move from higher energy level to lower energy level.
- holes in the valence band move from lower energy level to higher energy level.
पर्याय
a and b
b and c
d and a
a and c
Advertisements
उत्तर
a and c
Explanation:
In the valence band electrons are not capable of gaining energy from the external electric fields. While in the conduction band the electrons can gain energy from the external electric field.
When an electric field is applied across a semiconductor, the electrons in the conduction band (which is partially filled with electrons) get accelerated and acquire energy. They move from lower energy levels to higher energy levels. While the holes in the valence band move from higher energy level to lower energy level, where they will be having more energy.
APPEARS IN
संबंधित प्रश्न
When a forward bias is applied to a p-n junction, it ______.
In the following diagram 'S' is a semiconductor. Would you increase or decrease the value of R to keep the reading of the ammeter A constant when S is heated? Give reason for your answer.
With reference to semiconductor devices, define a p-type semiconductor and a Zener diode.
What is the use of Zener diode?
The graph shown in the figure represents a plot of current versus voltage for a given semiconductor. Identify the region, if any, over which the semiconductor has a negative resistance.
The power delivered in the plate circular of a diode is 1.0 W when the plate voltage is 36 V. Find the power delivered if the plate voltage is increased to 49 V. Assume Langmuir-Child equation to hold.
The dynamic plate resistance of a triode value is 10 kΩ. Find the change in the plate current if the plate voltage is changed from 200 V to 220 V.
The gain factor of an amplifier in increased from 10 to 12 as the load resistance is changed from 4 kΩ to 8 kΩ. Calculate (a) the amplification factor and (b) the plate resistance.
Answer the following question.
Why photodiodes are required to operate in reverse bias? Explain.
Of the diodes shown in the following diagrams, which one is reverse biased?
Consider an npn transistor with its base-emitter junction forward biased and collector base junction reverse biased. Which of the following statements are true?
- Electrons crossover from emitter to collector.
- Holes move from base to collector.
- Electrons move from emitter to base.
- Electrons from emitter move out of base without going to the collector.
Consider an npn transistor with its base-emitter junction forward biased and collector base junction reverse biased. Which of the following statements are true?
- Electrons crossover from emitter to collector.
- Holes move from base to collector.
- Electrons move from emitter to base.
- Electrons from emitter move out of base without going to the collector.
Figure shows the transfer characteristics of a base biased CE transistor. Which of the following statements are true?
At Vi = 0.4 V, transistor is in active state.
At Vi = 1 V, it can be used as an amplifier.
At Vi = 0.5 V, it can be used as a switch turned off.
At Vi = 2.5 V, it can be used as a switch turned on.
The breakdown in a reverse biased p–n junction diode is more likely to occur due to ______.
- large velocity of the minority charge carriers if the doping concentration is small.
- large velocity of the minority charge carriers if the doping concentration is large.
- strong electric field in a depletion region if the doping concentration is small.
- strong electric field in the depletion region if the doping concentration is large.
If each diode in figure has a forward bias resistance of 25 Ω and infinite resistance in reverse bias, what will be the values of the current I1, I2, I3 and I4?
Draw the circuit arrangement for studying V-I characteristics of a p-n junction diode in (i) forward biasing and (ii) reverse biasing. Draw the typical V-I characteristics of a silicon diode.
Describe briefly the following term:
breakdown voltage in reverse biasing
With reference to a semiconductor diode, define the potential barrier.
What is meant by forward biasing of a semiconductor diode?
Draw a labelled characteristic curve (l-V graph) for a semiconductor diode during forward bias.
