Advertisements
Advertisements
प्रश्न
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.
पर्याय
d and a
a and b
b and c
a and c
Advertisements
उत्तर
a and c
Explanation:
Transistor: A junction transistor is formed by sandwiching 2 thin layer of P-type semiconductors between two N-type semiconductors. or by sandwiching a thin taver of V-type semiconductors between two P-type semiconductors.
E — Emitter (emits majority charge carriers)
C — Collects majority charge carriers
B — Base (provide proper interaction between E and C)
In normal operation base-emitter is forward biased, i.e., the positive pole of the emitter-base battery is connected to the base and its negative pole is connected to the emitter. And collector-base junction is reverse biased, i.e., the positive pole of the collector base battery is connected to the collector and the negative pole to base. Thus, electron moves from emitter to base and crossovers from emitter to collector.
APPEARS IN
संबंधित प्रश्न
Explain the working of P-N junction diode in forward and reverse biased mode.
What happens when a forward bias is applied to a p-n junction?
In the following diagram, is the junction diode forward biased or reverse biased ?
Plot a graph showing variation of current versus voltage for the material GaAs ?
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.
In a photo diode, the conductive increases when the material is exposed to light. It is found that the conductivity changes only if the wavelength is less than 620 nm. What is the band gap?
(Use Planck constant h = 4.14 × 10-15 eV-s, Boltzmann constant k = 8·62 × 10-5 eV/K.)
A plate current of 10 mA is obtained when 60 volts are applied across a diode tube. Assuming the Langmuir-Child relation \[i_p \infty V_p^{3/2}\] to hold, find the dynamic resistance rp in this operating condition.
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.
Basic materials used in the present solid state electronic devices like diode, transistor, ICs, etc are ______.
We use alloys for making standard resistors because they have ____________.
The expected energy of the electron at absolute zero is called:-
Avalanche breakdown is due to ______.
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.
A Zener of power rating 1 W is to be used as a voltage regulator. If zener has a breakdown of 5 V and it has to regulate voltage which fluctuated between 3 V and 7 V, what should be the value of Rs for safe operation (Figure)?
The graph of potential barrier versus width of depletion region for an unbiased diode is shown in graph A. In comparison to A, graphs B and C are obtained after biasing the diode in different ways. Identify the type of biasing in B and C and justify your answer
| ‘A’ | ‘B’ | ‘C’ |
 |
 |
 |
Draw V-I characteristics of a p-n Junction diode.
Answer the following giving reasons:
A p-n junction diode is damaged by a strong current.
Read the following paragraph and answer the questions that follow.
| A semiconductor diode is basically a pn junction with metallic contacts provided at the ends for the application of an external voltage. It is a two-terminal device. When an external voltage is applied across a semiconductor diode such that the p-side is connected to the positive terminal of the battery and the n-side to the negative terminal, it is said to be forward-biased. When an external voltage is applied across the diode such that the n-side is positive and the p-side is negative, it is said to be reverse-biased. An ideal diode is one whose resistance in forward biasing is zero and the resistance is infinite in reverse biasing. When the diode is forward biased, it is found that beyond forward voltage called knee voltage, the conductivity is very high. When the biasing voltage is more than the knee voltage the potential barrier is overcome and the current increases rapidly with an increase in forward voltage. When the diode is reverse biased, the reverse bias voltage produces a very small current of about a few microamperes which almost remains constant with bias. This small current is a reverse saturation current. |
- In the given figure, a diode D is connected to an external resistance R = 100 Ω and an emf of 3.5 V. If the barrier potential developed across the diode is 0.5 V, the current in the circuit will be:
(a) 40 mA
(b) 20 mA
(c) 35 mA
(d) 30 mA - In which of the following figures, the pn diode is reverse biased?
(a)
(b)
(c)
(d)
- Based on the V-I characteristics of the diode, we can classify the diode as:
(a) bilateral device
(b) ohmic device
(c) non-ohmic device
(d) passive element
OR
Two identical PN junctions can be connected in series by three different methods as shown in the figure. If the potential difference in the junctions is the same, then the correct connections will be:
(a) in the circuits (1) and (2)
(b) in the circuits (2) and (3)
(c) in the circuits (1) and (3)
(d) only in the circuit (1) 
The V-I characteristic of a diode is shown in the figure. The ratio of the resistance of the diode at I = 15 mA to the resistance at V = -10 V is
(a) 100
(b) 106
(c) 10
(d) 10-6
Draw a labelled characteristic curve (l-V graph) for a semiconductor diode during forward bias.
