Advertisements
Advertisements
प्रश्न
A triode value operates at Vp = 225 V and Vg = −0.5 V.
The plate current remains unchanged if the plate voltage is increased to 250 V and the grid voltage is decreased to −2.5 V. Calculate the amplification factor.
Advertisements
उत्तर
Amplification factor for a triode valve,
\[\mu = \frac{\text{Change in Plate Voltage}}{\text{Change in Grid Voltage}}\]
At constant plate current,
\[\mu = \left(\frac{\delta V_P}{\delta V_G}\right)_{i_P = constant} \]
\[\mu = \frac{250 - 225}{2 . 5 - 0 . 5}\]
\[\mu = \frac{25}{2} = 12 . 5\]
This implies that the amplification factor of the triode is 12.5
APPEARS IN
संबंधित प्रश्न
Explain the working of P-N junction diode in forward and reverse biased mode.
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.
Draw its I – V characteristics of photodiode
Why is a zener diode considered as a special purpose semiconductor diode?
With reference to semi-conductors answer the following :
(i) What is the change in the resistance of the semi-conductor with increase in temperature ?
(ii) Name the majority charge carriers in n-type semi-conductor.
(iii) What is meant by doping ?
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.
In semiconductor physics, what is meant by:
(i) rectifier
(ii) an amplifier
(iii) an oscillator
Answer the following question.
Why photodiodes are required to operate in reverse bias? Explain.
Diffusion in a p-n junction is due to ______.
With reference to Semiconductor Physics,
Name the diode that emits spontaneous radiation when forward biased.
A – pn junction has a depletion layer of thickness .of the order of
Avalanche breakdown is due to ______.
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.
 (a) |
 (b) |
- Name the type of a diode whose characteristics are shown in figure (A) and figure (B).
- What does the point P in figure (A) represent?
- What does the points P and Q in figure (B) represent?
Write the property of a junction diode which makes it suitable for rectification of ac voltages.
Describe the following term briefly:
minority carrier injection in forward biasing.
Describe the following term briefly:
breakdown voltage in reverse biasing
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
Choose the correct circuit which can achieve the bridge balance.
