Many important questions are formed in competitive exams like CUET, JEE, NEET, and boards from Class 12 Physics. Below, we have provided Important Questions from Class 12 Physics Unit 9, Electronic Devices for your JEE Mains 2023 preparation. You can check it here for revision purposes.
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Electronic Devices – Semiconductor Class 12 JEE Main Questions and Answers
We’ve compiled a list of important questions about the Electronic Devices Class 12 physics unit 9 that you should not miss while studying for your JEE Main Exams.
Q.1. A carrier frequency of 1 MHz and peak value of 10 V is amplitude modulated with a signal frequency of 10 kHz with peak value of 0.5 V. Then the modulation index and the sideband frequencies respectively are
(a) 0.05 and 1 ± 0.010 MHz
(b) 0.5 and 1 ± 0.010 MHz
(c) 0.05 and 1 ± 0.005 MHz
(d) 0.5 and 1 ± 0.005 MHz
A.1. (b)
Q.2. . In the figure, V0 is the potential barrier across a p-n junction, when no battery is connected across the junction
(a) 1 and 3 both correspond to forward bias of junction
(b) 3 corresponds to forward bias of junction and 1 corresponds to reverse bias of junction
(c) 1 corresponds to forward bias and 3 corresponds to reverse bias of junction.
(d) 3 and 1 both correspond to reverse bias of junction.
A.2. (b)
Q.3. A transmitting antenna at the top of a tower has a height of 20 m. For obtaining 40 km as the maximum distance between the transmitter and receiver for satisfactory communication in LOS mode, the height of receiving antenna should be (radius of the earth R = 64 × 105 m)
(a) 30 m (b) 35 m (c) 40 m (d) 45 m
A.3. (d)
Q.4. Figure shows the transfer characteristics of a base biased CE transistor. Which of the following statements are true?
(a) At Vi = 0.4 V, the transistor is in active state.
(b) At Vi = 1 V, it can be used as an amplifier.
(c) At Vi = 0.5 V, it can be used as a switch turned off.
(d) At Vi = 2.5 V, it can be used as a switch turned on
A.4. (b,c,d)
Q.5. The electrical conductivity of pure germanium can be increased by
(a) increasing the temperature
(b) doping acceptor impurities
(c) doping donor impurities
(d) irradiating ultraviolet light on it.
A.5. (a,b,c,d)
Q.6. When a potential difference is applied across, the current passing through
(a) an insulator at 0 K is zero
(b) a semiconductor at 0 K is zero
(c) a metal at 0 K is finite
(d) a p-n diode at 300 K is finite, if it is reverse biased
A.6. (a,b,d)
Q.7. If the given diode is ideal, then which of the following statements are wrong for the output of the given circuit?
(a) It would be zero at all times.
(b) It would be like a half wave rectifier with positive cycles in output.
(c) It would be like a half wave rectifier with negative cycles in output.
(d) It would be like that of a full wave rectifier.
A.7. (a,b,d)
Q.8. A diode detector is used to detect an amplitude modulated wave of 60% modulation by using a condenser of capacity 250 pico farad in parallel with a load resistance 100 kilo ohm. Find the maximum modulated frequency (in kHz) which could be detected by it.
A.8. (10.61)
Q.9. Donor atoms are doped with pure germanium semiconductor in order to obtain an n-type semiconductor whose conductivity is 5 mho cm–1. The mobility of electrons in n-type germanium is 3900 cm2 V–1 s–1 and density of holes is negligible. The density of donor atoms is a × 1015 cm–3. Find the value of ‘a’.
A.9. (8)
Q.10. The T.V. signals have a bandwidth of 3.7 MHz. The number of T.V. channels that can be accommodated with a band of 3700 GHz is 10x. Find the value of ‘x’.
A.10. (6)
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