Semiconductors — JEE Main PYQs

A message signal of frequency 3 kHz is used to modulate a carrier signal of frequency 1.5 MHz . The bandwidth of the amplitude modulated wave is

A zener diode of power rating 1.6 W is to be used as voltage regulator. If the zener diode has a breakdown of 8 V and it has to regulate voltage fluctuating between 3 V and 10 V. The value of resistance $R_s$ for safe operation of diode will be:

A carrier wave of amplitude 15 V is modulated by a sinusoidal base band signal of amplitude 3 V. The ratio of maximum amplitude to minimum amplitude in an amplitude modulated wave is:

The logic performed by the circuit shown in figure is equivalent to :

The amplitude of $15\sin (1000\pi t)$ is modulated by $10\sin (4\pi t)$ signal. The amplitude modulated signal contains frequencies of

1. 500 Hz.
2. 2 Hz
3. 250 Hz
4. 498 Hz
5. 502 Hz

Choose the correct answer from the options given below:

In an n-p-n common emitter (CE) transistor the collector current changes from 5 mA to 16 mA for the change in base current from $100\mu A$ and $200\mu A$, respectively. The current gain of transistor is ______.

For the following circuit and given inputs A and B, choose the correct option for output 'Y'

From the given transfer characteristic of a transistor in CE configuration, the value of power gain of this configuration is $10^{\mathrm{x}}$, for ${\mathrm{R}}_{\mathrm{B}}=10\mathrm{k}\Omega$, and ${\mathrm{R}}_{\mathrm{C}}=1\mathrm{k}\Omega$. The value of x is ______.

The output from a NAND gate having inputs A and B given below will be.

Name the logic gate equivalent to the diagram attached

The resistivity ($\rho$) of semiconductor varies with temperature. Which of the following curve represents the correct behaviour

By what percentage will the transmission range of a TV tower be affected when the height of the tower is increased by $21\%$?

In satellite communication, the uplink frequency band used is:

The logic operations performed by the given digital circuit is equivalent to:

A modulating signal is a square wave, as shown in the figure.

If the carrier wave is given as $\mathrm{c}(\mathrm{t})=2\sin (8\pi \mathrm{t})$ volts, the modulation index is :

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R
Assertion A : Photodiodes are preferably operated in reverse bias condition for light intensity measurement.
Reason R : The current in the forward bias is more than the current i …

The logic gate equivalent to the given circuit diagram is :

A message signal of frequency 5 kHz is used to modulate a carrier signal of frequency 2 MHz. The bandwidth for amplitude modulation is:

Given below are two statements: one is labeled as Assertion A and the other is labeled as Reason R
Assertion A: Photodiodes are used in forward bias usually for measuring the light intensity.
Reason R: For a p-n junction diode, at applied voltage V the current in the forward bias …

Statement I: When a Si sample is doped with Boron, it becomes P type and when doped by Arsenic it becomes N-type semi conductor such that P-type has excess holes and N-type has excess electrons.

Statement II : When such P-type and N-type semi-conductors, are fused to make a junc …

Which of the following statement is not correct in the case of light emitting diodes?
A. It is a heavily doped $\mathrm{p}-\mathrm{n}$ junction.
B. It emits light only when it is forward biased.
C. It emits light only when it is reverse biased.
D. The energy of the light emitte …

For the given logic gates combination, the correct truth table will be

The modulation index for an A.M. wave having maximum and minimum peak to peak voltages of 14 mV and 6 mV respectively is:

The output Y for the inputs A and B of circuit is given by

Truth table of the shown circuit is :

The output waveform of the given logical circuit for the following inputs A and B as shown below, is :

A sinusoidal carrier voltage is amplitude modulated. The resultant amplitude modulated wave has maximum and minimum amplitude of 120 V and 80 V respectively. The amplitude of each sideband is :

The amplitude of $15\sin (1000\pi \mathrm{t})$ is modulated by $10\sin (4\pi \mathrm{t})$ signal. The amplitude modulated signal contains frequency(ies) of
(A) 500 Hz
(B) 2 Hz
(C) 250 Hz
(D) 498 Hz
(E) 502 Hz

Choose the correct answer from the options given below:

The effect of increase in temperature on the number of electrons in conduction band (${\mathrm{n}}_{\mathrm{e}}$) and resistance of a semiconductor will be as:

Given below are two statements

Statement I: For transmitting a signal, size of antenna ( $l$ ) should be comparable to wavelength of signal (at least $l=\frac{\lambda }{4}$ in dimension).

Statement II: In amplitude modulation, amplitude of carrier wave remains constant (unchange …

Given below are two statements:

Statement I: In a typical transistor, all three regions emitter, base and collector have same doping level.
Statement II: In a transistor, collector is the thickest and base is the thinnest segment.
In the light of the above statements, choose the …

In an amplitude modulation, a modulating signal having amplitude of XV is superimposed with a carrier signal of amplitude YV in first case. Then, in second case, the same modulating signal is superimposed with different carrier signal of amplitude 2YV. The ratio of modulation ind …

Choose the correct statement about Zener diode:

A modulating signal $2\sin \left(6.28\times 10^6\right)t$ is added to the carrier signal $4\sin \left(12.56\times 10^9\right)t$ for amplitude modulation. The combined signal is passed through a non-linear square law device. The output is then passed through a band pass …

A 8 V Zener diode along with a series resistance R is connected across a 20 V supply (as shown in the figure). If the maximum Zener current is 25 mA, then the minimum value of $R$ will be ______ $\Omega$.

Identify the solar cell characteristics from the following options :

In the case of amplitude modulation to avoid distortion the modulation index ( $\mu$ ) should be :

An n.p.n transistor with current gain $\beta =100$ in common emitter configuration is shown in figure. The output voltage of the amplifier will be

A FM Broad cast transmitter, using modulating signal of frequency 20 kHz has a deviation ratio of 10. The Bandwidth required for transmission is :

A logic gate circuit has two inputs A and B and output Y. The voltage waveforms of $\mathrm{A},\mathrm{B}$ and Y are shown below

The logic gate circuit is

In the circuit, the logical value of $\mathrm{A}=1$ or $\mathrm{B}=1$ when potential at A or B is 5 V and the logical value of $\mathrm{A}=0$ or $\mathrm{B}=0$ when potential at A or B is 0 V.

The truth table of the given circuit will be :

The required height of a TV tower which can cover the population of 6.03 lakh is h . If the average population density is 100 per square km and the radius of earth is 6400 km , then the value of $h$ will be $\_\_\_\_$ m.

The maximum and minimum voltage of an amplitude modulated signal are 60 V and 20 V respectively. The percentage modulation index will be:

The typical transfer characteristic of a transistor in CE configuration is shown in figure. A load resistor of $2\mathrm{k}\Omega$ is connected in the collector branch of the circuit used. The input resistance of the transistor is $0.50\mathrm{k}\Omega$. The voltage gain of the …

For a constant collector-emitter voltage of 8 V, the collector current of a transistor reached to the value of 6 mA from 4 mA, whereas base current changed from $20\mu \mathrm{A}$ to $25\mu \mathrm{A}$ value. If transistor is in active state, small signal current gain (curren …

In AM modulation, a signal is modulated on a carrier wave such that maximum and minimum amplitude are found to be 6 V and 2 V respectively. The modulation index is

In the circuit shown below, maximum zener diode current will be ______ mA

In the given circuit the input voltage ${\mathrm{V}}_{\text{in }}$ is shown in figure. The cut-in voltage of $\mathrm{p}-\mathrm{n}$ junction diode ( ${\mathrm{D}}_1$ or ${\mathrm{D}}_2$ ) is 0.6 V. Which of the following output voltage ( ${\mathrm{V}}_0$ ) waveform across the dio …

Amplitude modulated wave is represented by $V_{\text{AM }}=10\left[1+0.4\cos \left(2\pi \times 10^4\mathrm{t}\right)\right]\cos \left(2\pi \times 10^7\mathrm{t}\right)$.

The total bandwidth of the amplitude modulated wave is:

A Zener of breakdown voltage ${\mathrm{V}}_{\mathrm{Z}}=8\mathrm{V}$ and maximum zener current, ${\mathrm{I}}_{\mathrm{ZM}}=10\mathrm{mA}$ is subjected to an input voltage ${\mathrm{V}}_{\mathrm{i}}=10\mathrm{V}$ with series resistance $\mathrm{R}=100\Omega$. In the given circui …

For a transistor to act as a switch, it must be operated in