For the diode, the characteristic curves are given at different temperature. The relation between the temperatures is [RPET 1990]

\[{{T}_{1}}={{T}_{2}}={{T}_{3}}\]

Given below are four logic gate symbol (figure). Those for OR, NOR and NAND are respectively [NSEP 1994]

\[T\sqrt{\frac{\rho -1}{\rho }}\]

If A and B are two inputs in AND gate, then AND gate has an output of 1 when the values of A and B are [TNPCEE 2002]

The magnitude of the tangential acceleration of the bob \[|{{a}_{T}}|\,=g\sin \theta \]

When a potential difference is applied across, the current passing through [IIT-JEE 1999]

If assertion is true but reason is false.

A semiconductor at \[0K\] is zero

If assertion is true but reason is false.

A P-N diode at \[300K\] is finite, if it is reverse biased

On applying a potential of ? 1 volt at the grid of a triode, the following relation between plate voltage Vp (volt) and plate current \[{{I}_{p}}(\text{in }mA)\] is found \[{{I}_{p}}=0.125\,{{V}_{p}}-7.5\]If on applying ? 3 volt potential at grid and 300 V potential at plate, the plate current is found to be 5mA, then amplification factor of the triode is

If assertion is true but reason is false.

The plate current in a triode is given by \[{{I}_{p}}=0.004\ {{({{V}_{p}}+10{{V}_{g}})}^{3/2}}mA\]where Ip, Vp and Vg are the values of plate current, plate voltage and grid voltage, respectively. What are the triode parametersm, rp and gm for the operating point at \[{{V}_{p}}=120\,volt\] and \[{{V}_{g}}=-\,2\,volt\]?

If assertion is true but reason is false.

The diagram of a logic circuit is given below. The output F of the circuit is represented by

If assertion is true but reason is false.

In NPN transistor, 1010 electrons enters in emitter region in 10?6 sec. If 2% electrons are lost in base region then collector current and current amplification factor (b) respectively are

If assertion is true but reason is false.

Assertion : The temperature coefficient of resistance is positive for metals and negative for P-type semiconductor. Reason : The effective charge carriers in metals are negatively charged whereas in P-type semiconductor they are positively charged. [AIIMS 1996]

If assertion is true but reason is false.

If both assertion and reason are true and the reason is the correct explanation of the assertion.

If both assertion and reason are true but reason is not the correct explanation of the assertion.

If assertion is true but reason is false.

If the assertion and reason both are false.

If assertion is false but reason is true.

Assertion : If the temperature of a semiconductor is increased then it's resistance decreases. Reason : The energy gap between conduction band and valence band is very small [AIIMS 1997]

If both assertion and reason are true but reason is not the correct explanation of the assertion.

If both assertion and reason are true and the reason is the correct explanation of the assertion.

If both assertion and reason are true but reason is not the correct explanation of the assertion.

If assertion is true but reason is false.

If the assertion and reason both are false.

If assertion is false but reason is true.

Assertion : The resistivity of a semiconductor increases with temperature. Reason : The atoms of a semiconductor vibrate with larger amplitude at higher temperature there by increasing it's resistivity. [AIIMS 2003]

If assertion is false but reason is true.

If both assertion and reason are true and the reason is the correct explanation of the assertion.

If both assertion and reason are true but reason is not the correct explanation of the assertion.

If assertion is true but reason is false.

If the assertion and reason both are false.

If assertion is false but reason is true.

Assertion : NAND or NOR gates are called digital building blocks. Reason : The repeated use of NAND (or NOR) gates can produce all the basic or complicated gates.

If both assertion and reason are true but reason is not the correct explanation of the assertion.

If both assertion and reason are true and the reason is the correct explanation of the assertion.

If both assertion and reason are true but reason is not the correct explanation of the assertion.

If assertion is true but reason is false.

If the assertion and reason both are false.

If assertion is false but reason is true.

Assertion : A transistor is a voltage-operating device. Reason : Base current is greater than the collector current.

If assertion is false but reason is true.

If both assertion and reason are true and the reason is the correct explanation of the assertion.

If both assertion and reason are true but reason is not the correct explanation of the assertion.

If assertion is true but reason is false.

If the assertion and reason both are false.

If assertion is false but reason is true.

Assertion : The dominant mechanism for motion of charge carriers in forward and reverse biased silicon P-N junction are drift in both forward and reverse bias. Reason : In reverse biasing, no current flow through the junction.

If assertion is false but reason is true.

If both assertion and reason are true and the reason is the correct explanation of the assertion.

If both assertion and reason are true but reason is not the correct explanation of the assertion.

If the assertion and reason both are false.

If assertion is false but reason is true.

Assertion : The number of electrons in a P-type silicon semiconductor is less than the number of electrons in a pure silicon semiconductor at room temperature. Reason : It is due to law of mass action. [AIIMS 2005]

If both assertion and reason are true but reason is not the correct explanation of the assertion.

If both assertion and reason are true and the reason is the correct explanation of the assertion.

If both assertion and reason are true but reason is not the correct explanation of the assertion.

If the assertion and reason both are false.

If assertion is false but reason is true.

Assertion : The logic gate NOT can be built using diode. Reason : The output voltage and the input voltage of the diode have 180° phase difference. [AIIMS 2005]

If assertion is false but reason is true.

If both assertion and reason are true and the reason is the correct explanation of the assertion.

If both assertion and reason are true but reason is not the correct explanation of the assertion.

If the assertion and reason both are false.

If assertion is false but reason is true.

25 + Mcqs in Semiconducting Devices in Physics Page 1 McqOptions

1.	For the diode, the characteristic curves are given at different temperature. The relation between the temperatures is [RPET 1990]
A.	\[{{T}_{1}}={{T}_{2}}={{T}_{3}}\]
B.	\[{{T}_{1}}<{{T}_{2}}<{{T}_{3}}\]
C.	Mg/K
D.	None of the above
Answer» C. Mg/K

Discussion

2.	The mutual characteristic curves of a triode are as shown in figure. The cut off voltage for the triode is
A.	0 V
B.	2 V
C.	12.0 m
D.	6 V
Answer» D. 6 V

Discussion

3.	The figure represents variation of triode parameter (m or rp or gm) with the plate current. The correct variation of m and rp are given, respectively by the curves
A.	A and B
B.	B and C
C.	\[2\pi \frac{mYA}{KL}\]
D.	None of the above
Answer» D. None of the above

Discussion

4.	The variation of anode current in a triode corresponding to a change in grid potential at three different values of the plate potential is shown in the diagram. The mutual conductance of the triode is [CPMT 1986, 88]
A.	2.5 m mho
B.	5.0 m mho
C.	\[3k\]
D.	10.0 m mho
Answer» B. 5.0 m mho

Discussion

5.	The given figure shows the wave forms for two inputs A and B and that for the output Y of a logic circuit. The logic circuit is [UPSEAT 2002] (Y)
A.	An AND gate
B.	An OR gate
C.	\[t=2{{t}_{0}}\]
D.	An NOT gate
Answer» B. An OR gate

Discussion

6.	A gate in which all the inputs must be low to get a high output is called [UPSEAT 2004]
A.	A NAND gate
B.	An inverter
C.	\[2\pi \sqrt{\frac{L}{g}}\]
D.	An AND gate
Answer» C. \[2\pi \sqrt{\frac{L}{g}}\]

Discussion

7.	Which logic gate is represented by following diagram [DCE 2001]
A.	AND
B.	OR
C.	5 seconds / day
D.	XOR
Answer» B. OR

Discussion

8.	Given below are four logic gate symbol (figure). Those for OR, NOR and NAND are respectively [NSEP 1994]
A.	1, 4, 3
B.	4, 1, 2
C.	\[T\sqrt{\frac{\rho -1}{\rho }}\]
D.	4, 2, 1
Answer» D. 4, 2, 1

Discussion

9.	If A and B are two inputs in AND gate, then AND gate has an output of 1 when the values of A and B are [TNPCEE 2002]
A.	A = 0, B = 0
B.	A = 1, B = 1
C.	The magnitude of the tangential acceleration of the bob \[\|{{a}_{T}}\|\,=g\sin \theta \]
D.	A = 0, B = 1
Answer» C. The magnitude of the tangential acceleration of the bob \[\|{{a}_{T}}\|\,=g\sin \theta \]

Discussion

10.	How many NAND gates are used to form an AND gate [MP PET 2004]
A.	1
B.	2
C.	\[{{T}_{1}}={{T}_{2}}\]
D.	4
Answer» C. \[{{T}_{1}}={{T}_{2}}\]

Discussion

11.	A 2V battery is connected across the points A and B as shown in the figure given below. Assuming that the resistance of each diode is zero in forward bias and infinity in reverse bias, the current supplied by the battery when its positive terminal is connected to A is [UPSEAT 2002]
A.	0.2 A
B.	0.4 A
C.	0.1456 sec
D.	0.1 A
Answer» B. 0.4 A

Discussion

12.	When a potential difference is applied across, the current passing through [IIT-JEE 1999]
A.	An insulator at \[0K\] is zero
B.	A semiconductor at \[0K\] is zero
C.	If assertion is true but reason is false.
D.	A P-N diode at \[300K\] is finite, if it is reverse biased
Answer» C. If assertion is true but reason is false.

Discussion

13.	On applying a potential of ? 1 volt at the grid of a triode, the following relation between plate voltage Vp (volt) and plate current \[{{I}_{p}}(\text{in }mA)\] is found \[{{I}_{p}}=0.125\,{{V}_{p}}-7.5\]If on applying ? 3 volt potential at grid and 300 V potential at plate, the plate current is found to be 5mA, then amplification factor of the triode is
A.	100
B.	50
C.	If assertion is true but reason is false.
D.	20
Answer» B. 50

Discussion

14.	The plate current in a triode is given by \[{{I}_{p}}=0.004\ {{({{V}_{p}}+10{{V}_{g}})}^{3/2}}mA\]where Ip, Vp and Vg are the values of plate current, plate voltage and grid voltage, respectively. What are the triode parametersm, rp and gm for the operating point at \[{{V}_{p}}=120\,volt\] and \[{{V}_{g}}=-\,2\,volt\]?
A.	10, 16.7 kW, 0.6 m mho
B.	15, 16.7 kW, 0.06 m mho
C.	If assertion is true but reason is false.
D.	None of these
Answer» B. 15, 16.7 kW, 0.06 m mho

Discussion

15.	The diagram of a logic circuit is given below. The output F of the circuit is represented by
A.	\[W.(X+Y)\]
B.	\[W\cdot \,(X\cdot Y)\]
C.	If assertion is true but reason is false.
D.	\[W+(X+Y)\]
Answer» D. \[W+(X+Y)\]

Discussion

16.	In NPN transistor, 1010 electrons enters in emitter region in 10?6 sec. If 2% electrons are lost in base region then collector current and current amplification factor (b) respectively are
A.	1.57 mA, 49
B.	1.92 mA, 70
C.	If assertion is true but reason is false.
D.	2.25 mA, 100
Answer» B. 1.92 mA, 70

Discussion

17.	Find VAB [RPMT 2000]
A.	10 V
B.	20 V
C.	If assertion is true but reason is false.
D.	None of these
Answer» B. 20 V

Discussion

18.	Assertion : The temperature coefficient of resistance is positive for metals and negative for P-type semiconductor. Reason : The effective charge carriers in metals are negatively charged whereas in P-type semiconductor they are positively charged. [AIIMS 1996]
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» C. If assertion is true but reason is false.

Discussion

19.	Assertion : If the temperature of a semiconductor is increased then it's resistance decreases. Reason : The energy gap between conduction band and valence band is very small [AIIMS 1997]
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

20.	Assertion : The resistivity of a semiconductor increases with temperature. Reason : The atoms of a semiconductor vibrate with larger amplitude at higher temperature there by increasing it's resistivity. [AIIMS 2003]
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» E. If assertion is false but reason is true.

Discussion

21.	Assertion : NAND or NOR gates are called digital building blocks. Reason : The repeated use of NAND (or NOR) gates can produce all the basic or complicated gates.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

22.	Assertion : A transistor is a voltage-operating device. Reason : Base current is greater than the collector current.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» E. If assertion is false but reason is true.

Discussion

23.	Assertion : The dominant mechanism for motion of charge carriers in forward and reverse biased silicon P-N junction are drift in both forward and reverse bias. Reason : In reverse biasing, no current flow through the junction.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	\[a{{\omega }^{2}}\]
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» E. If assertion is false but reason is true.

Discussion

24.	Assertion : The number of electrons in a P-type silicon semiconductor is less than the number of electrons in a pure silicon semiconductor at room temperature. Reason : It is due to law of mass action. [AIIMS 2005]
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	\[\frac{2\pi }{\sqrt{3}}\]
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

25.	Assertion : The logic gate NOT can be built using diode. Reason : The output voltage and the input voltage of the diode have 180° phase difference. [AIIMS 2005]
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	\[100\,\,m/{{s}^{2}}\]
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» E. If assertion is false but reason is true.

Discussion

Explore topic-wise MCQs in Physics.

For the diode, the characteristic curves are given at different temperature. The relation between the temperatures is [RPET 1990]

The mutual characteristic curves of a triode are as shown in figure. The cut off voltage for the triode is

The figure represents variation of triode parameter (m or rp or gm) with the plate current. The correct variation of m and rp are given, respectively by the curves

The variation of anode current in a triode corresponding to a change in grid potential at three different values of the plate potential is shown in the diagram. The mutual conductance of the triode is [CPMT 1986, 88]

The given figure shows the wave forms for two inputs A and B and that for the output Y of a logic circuit. The logic circuit is [UPSEAT 2002] (Y)

A gate in which all the inputs must be low to get a high output is called [UPSEAT 2004]

Which logic gate is represented by following diagram [DCE 2001]

Given below are four logic gate symbol (figure). Those for OR, NOR and NAND are respectively [NSEP 1994]

If A and B are two inputs in AND gate, then AND gate has an output of 1 when the values of A and B are [TNPCEE 2002]

How many NAND gates are used to form an AND gate [MP PET 2004]

A 2V battery is connected across the points A and B as shown in the figure given below. Assuming that the resistance of each diode is zero in forward bias and infinity in reverse bias, the current supplied by the battery when its positive terminal is connected to A is [UPSEAT 2002]

When a potential difference is applied across, the current passing through [IIT-JEE 1999]

The diagram of a logic circuit is given below. The output F of the circuit is represented by

In NPN transistor, 1010 electrons enters in emitter region in 10?6 sec. If 2% electrons are lost in base region then collector current and current amplification factor (b) respectively are

Find VAB [RPMT 2000]

Assertion : The temperature coefficient of resistance is positive for metals and negative for P-type semiconductor. Reason : The effective charge carriers in metals are negatively charged whereas in P-type semiconductor they are positively charged. [AIIMS 1996]

Assertion : If the temperature of a semiconductor is increased then it's resistance decreases. Reason : The energy gap between conduction band and valence band is very small [AIIMS 1997]

Assertion : The resistivity of a semiconductor increases with temperature. Reason : The atoms of a semiconductor vibrate with larger amplitude at higher temperature there by increasing it's resistivity. [AIIMS 2003]

Assertion : NAND or NOR gates are called digital building blocks. Reason : The repeated use of NAND (or NOR) gates can produce all the basic or complicated gates.

Assertion : A transistor is a voltage-operating device. Reason : Base current is greater than the collector current.

Assertion : The dominant mechanism for motion of charge carriers in forward and reverse biased silicon P-N junction are drift in both forward and reverse bias. Reason : In reverse biasing, no current flow through the junction.

Assertion : The number of electrons in a P-type silicon semiconductor is less than the number of electrons in a pure silicon semiconductor at room temperature. Reason : It is due to law of mass action. [AIIMS 2005]

Assertion : The logic gate NOT can be built using diode. Reason : The output voltage and the input voltage of the diode have 180° phase difference. [AIIMS 2005]