Very Short Question Answers

Q1. What is an n-type semiconductor? What are the majority and minority charge carriers in it?

Ans.

n-type semiconductor: Germanium or silicon doped with pentavalent impurity like arsenic is called n- type semiconductor.Majority charge carriers: electrons

                          Minority charge carriers: holes.

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Q2. What are intrinsic and extrinsic semiconductors?

Ans.

Intrinsic semiconductor: Pure semiconductor like silicon is called intrinsic semiconductor.

Extrinsic semiconductor: A semiconductor doped with trivalent or pentavalent impurity is called extrinsic semiconductor.

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Q3. What is a p-type semiconductor? What are the majority and minority charge carries in it?

Ans.

p-type semiconductor: Germanium or silicon doped with trivalent impurity like indium is called p-type semiconductor.Majority charge carriers: holes

      Minority charge carriers: electrons.

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Q4. What is p-n unction diode? Define depletion layer?

Ans.

 p-n junction diode: An arrangement consisting of p-type semiconductor brought in close contact with n-type semiconductor is called p-n junction diode

Depletion layer: The region near the p-n junction which is free from mobile charge carriers is called depletion layer.

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Q5. How is a battery connected to a junction diode in i) forward bias and ii) reverse bias?

Ans.

 Forward bias: In forward bias, the p-side of diode is connected to positive terminal of battery and n-side connected to negative terminal of battery.

Reverse bias: In reverse bias, the p-side of diode is connected to negative terminal of battery and n –side connected to positive terminal of battery.

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Q6. What is the maximum percentage of rectification in half wave and full wave rectifiers?

Ans.

Maximum percentage of rectification in half wave rectifier is 40.6 %. Maximum percentage of rectification in full wave rectifier is 81.2%.

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Q7. What is Zener voltage and how will a Zener diode be connected in circuits generally?

Ans.

 Zener voltage: The reverse bias voltage of Zener diode, at which current increase suddenly is called Zener voltage. Zener diode is connected in reverse bias.

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Q8. Write Expressions for the efficiency of a full wave rectifier and a half wave rectifier?

Ans.

      Efficiency of full wave rectifier  $\eta =\frac{0.812\times \, R_{L}}{r
_{f}+R_{L}}$

Efficiency of half wave rectifier   $\eta =\frac{0.406\times \, R_{L}}{r
_{f}+R_{L}}$

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Q9. What happens to the width of the depletion layer in a p-n junction diode? When it is i) forward biased and ii)reverse biased?

Ans.

In forward bias the width of depletion layer of a diode decreases.

In reverse bias, the width of depletion layer of a diode increases

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Q10. Draw the circuit symbols for p-n-p and n-p-n transistors?

Ans.

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Q11. Define amplifier and amplification factor

Ans.

Amplifier: The process of raising the strength of a signal is called amplification.

The device used to do amplification is called amplifier.

Amplification factor(A): The ratio of output voltage to input voltage is called amplification factor $ A=\frac{V_{\circ}}{V_{i}} $

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Q12. In which bias can a Zener diode be used as voltage regulator?

Ans.

Reverse bias.

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Q13. Which gates are called universal gates?

Ans.

NAND and NOR gates.

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Q14. Write the truth table of NAND gate. How does it differ from AND gate?

Ans. NAND gate truth table 

$A$	$B$	$Y= \overline{A.B}$
$0$	$0$	$1$
$0$	$1$	$1$
$1$	$0$	$1$
$1$	$1$	$0$

The output of NAND gate is an inversion of AND gate.

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