CBSE Physics Semi-Conductor Devices Expected Questions : Unit XI
[Short/V. Short Questions—1, 2 Marks Questions]
1. How does the conductivity of a semiconductor change with temperature ?
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2. In the following diagrams, indicate which of the diodes are forward biased and which are reverse biased ?
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3. Write the truth table for AND gate.
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4. In a circuit shown, a switch which is open represents logic state 0 and the switch is closed represents logic state 1. The lamp L is lit when output is in logic state 1. What type of gates are represented by circuits in (i) and (ii) ?
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5. The output of an OR gate is connected to both the inputs of NAND gate. Draw the logic circuit of this combination of gates and write its truth table.
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6. When the voltage drop across ap — n junction diode is increased from 0 • 65 V and 0. 70 V, the change in the diode current is 5 mA. What is the dynamic resistance of diode ?
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7. When the voltage across/? — n junction diodes is increased from 0 • 70 V to 0. 71V, the change in diode current is 10 mA. What is the dynamic resistance of the diode ?
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8. Write the truth table for OR gate.
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9. Draw a circuit diagram for use of PN junction as a half wave rectifier.
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10. Which biasing will make the resistance of p — n junction high ?
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11. Draw logic symbol for a NAND gate.
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12. Draw a graph showing the variation of current with voltage for p — n junction diode.
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