A semiconductor device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops almost to zero. The device may be
| (a) A P-type semiconductor | (b) An N-type semiconductor |
| (c) A PN-junction | (d) An intrinsic semiconductor |
(c) A PN-junction
On increasing the reverse bias to a large value in a PN-junction diode, current
| (a) Increases slowly | (b) Remains fixed |
(c) Suddenly increases |
(d) Decreases slowly |
(c) Suddenly increases
Electric current is due to drift of electrons in
| (a) Metallic conductors | (b) Semi-conductors | (c) Both (a) and (b) | (d) None of these |
(c) Both (a) and (b)
If ne and vd be the number of electrons and drift velocity in a semiconductor. When the temperature is increased
|
(a) ne increases and vd decreases |
(b) ne decreases and vd increases |
| (c) Both ne and vd increases | (d) Both ne and vd decreases |
(a) ne increases and vd decreases
A piece of semiconductor is connected in series in an electric circuit. On increasing the temperature, the current in the circuit will
| (a) Decrease | (b) Remain unchanged | (c) Increase | (d) Stop flowing |
(c) Increase
A hole in a P-type semiconductor is
| (a) An excess electron | (b) A missing electron |
|
(c) A missing atom |
(d) A donor level |
(b) A missing electron
In an insulator, the forbidden energy gap between the valence band and conduction band is of the order of
| (a) 1 MeV | (b) 0.1 MeV |
(c) 1eV |
(d) 5 eV |
(d) 5 eV
Bonding in a germanium crystal (semi- conductor) is
| (a) Metallic | (b) Ionic |
(c) Vander Waal's type |
(d) Covalent |
(d) Covalent
In the following circuit find I1 and I2
|
(a) 0, 0 |
(b) 5 mA, 5 mA |
(c) 5 mA, 0 |
(d) 0, 5 mA |
(d) 0, 5 mA
For a triode, at 
volt, the following observations were taken
, 
. The value of plate resistance will be
|
(a) 25 kW |
(b) 20.8 kW |
(c) 12.5 kW |
(d) 100 kW |
(c) 12.5 kW
Which gates is represented by this figure
|
(a) NAND gate |
(b) AND gate |
(c) NOT gate |
(d) OR gate |
(a) NAND gate
Which of the following gates will have an output of 1
|
(a)
(a)
|
(b)
|
(c)
|
(d)
|
(c)
For the given combination of gates, if the logic states of inputs A, B, C are as follows A = B = C = 0 and A = B = 1, C = 0 then the logic states of output D are
|
(a) 0, 0 |
(b) 0, 1 |
(c) 1, 0 |
(d) 1, 1 |
(d) 1, 1
In the given figure, which of the diodes are forward biased ?
1.
2.
3. 
4. 
5. 
|
(a) 1, 2, 3 |
(b) 2, 4, 5 |
(c) 1, 3, 4 |
(d) 2, 3, 4 |
(b) 2, 4, 5
Which of the energy band diagrams shown in the figure corresponds to that of a semiconductor
|
(a)
|
(b)
|
(c)
|
(d)
|
(d)
Which of the following energy band diagram shows the N-type semiconductor
|
(a)
|
(b)
|
(c)
|
(d)
(b)
Question 671 Mark The plate characteristic curve of a diode in space charge limited region is as shown in the figure. The slope of curve at point P is 5.0 mA/V. The static plate resistance of diode will be
Answer View full question & answer→(c) 333.3W Question 681 Mark In the circuit given below, V(t) is the sinusoidal voltage source, voltage drop VAB(t) across the resistance R is
Answer View full question & answer→(d) Has different peak values during positive and negative half cycle Question 691 Mark In a semiconductor, the concentration of electrons is 8
Answer View full question & answer→(b) N-type Question 701 Mark The diode shown in the circuit is a silicon diode. The potential difference between the points A and B will be
Answer View full question & answer→(a) 6 V Question 711 Mark Ge and Si diodes conduct at 0.3 V and 0.7 V respectively. In the following figure if Ge diode connection are reversed, the valve of V0 changes by
Answer View full question & answer→(b) 0.4 V Question 721 Mark 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
Answer View full question & answer→(a) 0.2 A Question 731 Mark Of the diodes shown in the following diagrams, which one is reverse biased
Answer View full question & answer→(c)
Question 741 Mark Assertion : A P-N photodiode is made from a semiconductor for which Eg = 2.8 eV. This photo diode will not detect the wavelength of 6000 nm. Reason : A PN photodiode detect wavelength l if
Answer View full question & answer→(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. Question 751 Mark Assertion : De-morgan's theorem
Reason : In the following circuit, for output inputs ABC are 101
Answer View full question & answer→(c) If assertion is true but reason is false. Question 761 Mark Assertion : NOT gate is also called inverter circuit. Reason : NOT gate inverts the input order.
Answer View full question & answer→(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. Question 771 Mark Assertion : Zener diode works on a principle of breakdown voltage. Reason : Current increases suddenly after breakdown voltage.
Answer View full question & answer→(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. Question 781 Mark Assertion : V-i characteristic of P-N junction diode is same as that of any other conductor. Reason : P-N junction diode behave as conductor at room temperature.
Answer View full question & answer→(d) If the assertion and reason both are false. Question 791 Mark Assertion : At 0 K Germanium is a superconductor. Reason : At 0 K Germanium offers zero resistance.
Answer View full question & answer→(d) If the assertion and reason both are false. Question 801 Mark 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.
Answer View full question & answer→(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. Question 811 Mark Assertion : A transistor is a voltage-operating device. Reason : Base current is greater than the collector current.
Answer View full question & answer→(d) If the assertion and reason both are false. Question 821 Mark Assertion : In transistor common emitter mode as an amplifier is preferred over common base mode. Reason : In common emitter mode the input signal is connected in series with the voltage applied to the base emitter function.
Answer View full question & answer→(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. Question 831 Mark Assertion : Two P-N junction diodes placed back to back, will work as a NPN transistor. Reason : The P-region of two PN junction diodes back to back will form the base of NPN transistor.
Answer View full question & answer→(d) If the assertion and reason both are false. Question 841 Mark Assertion : Semiconductors do not Obey's Ohm's law. Reason : Current is determined by the rate of flow of charge carriers.
Answer View full question & answer→(d) If assertion is false but reason is true. Question 851 Mark Assertion : We can measure the potential barrier of a PN junction by putting a sensitive voltmeter across its terminals. Reason : The current through the PN junction is not same in forward and reversed bias.
Answer View full question & answer→(d) If assertion is false but reason is true. Question 861 Mark Assertion : Silicon is preferred over germanium for making semiconductor devices. Reason : The energy gap for germanium is more than the energy gap of silicon.
Answer View full question & answer→(c) If assertion is true but reason is false. Question 871 Mark 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
Answer View full question & answer→(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. Question 881 Mark Assertion : Base in a transistor is made very thin as compared to collector and emitter regions. Reason : Due to thin base power gain and voltage gain is obtained by a transistor.
Answer View full question & answer→(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. Question 891 Mark 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.
Answer View full question & answer→(d) If the assertion and reason both are false. Question 901 Mark Assertion : A transistor amplifier in common emitter configuration has a low input impedence. Reason : The base to emitter region is forward biased.
Answer View full question & answer→(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. Question 911 Mark Assertion : In a common emitter transistor amplifier the input current is much less than the output current. Reason : The common emitter transistor amplifier has very high input impedance.
Answer View full question & answer→(c) If assertion is true but reason is false. Question 921 Mark 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
Answer View full question & answer→(a) An AND gate Question 931 Mark A full wave rectifier circuit along with the input and output voltages is shown in the figure
(b) B, D Question 941 Mark The slopes of anode and mutual characteristics of a triode are 0.02 mA V–1 and 1 mA V–1 respectively. What is the amplification factor of the valve
Answer View full question & answer→(b) 50 Question 951 Mark Amplification factor of a triode is 10. When the plate potential is 200 volt and grid potential is – 4 volt, then the plate current of 4mA is observed. If plate potential is changed to 160 volt and grid potential is kept at – 7 volt, then the plate current will be
Answer View full question & answer→(a) 1.69 mA Question 961 Mark For a triode m = 64 and gm =1600 m mho. It is used as an amplifier and an input signal of 1V (rms) is applied. The signal power in the load of 40 kW will be
Answer View full question & answer→(c) 25.6 mW Question 971 Mark A triode whose mutual conductance is 2.5 m A/volt and anode resistance is 20 kilo ohm, is used as an amplifier whose amplification is 10. The resistance connected in plate circuit will be
Answer View full question & answer→(b) 5 kW Question 981 Mark A change of 0.8 mA in the anode current of a triode occurs when the anode potential is changed by 10 V. If m = 8 for the triode, then what change in the grid voltage would be required to produce a change of 4 mA in the anode current
Answer View full question & answer→(a) 6.25 V Question 991 Mark A metallic surface with work function of 2 eV, on heating to a temperature of 800 K gives an emission current of 1 mA. If another metallic surface having the same surface area, same emission constant but work function 4 eV is heated to a temperature of 1600 K, then the emission current will be
Answer View full question & answer→(c) 4 mA Question 1001 Mark The junction diode in the following circuit requires a minimum current of 1 mA to be above the knee point (0.7 V) of its I-V characteristic curve. The voltage across the diode is independent of current above the knee point. If VB = 5V, then the maximum value of R so that the voltage is above the knee point, will be
Answer View full question & answer→(a) 4.3 kW |
