Semiconductors — JEE Main PYQs

In the following circuit, the correct relation between output (Y) and inputs A and B will be:

For using a multimeter to identify diode from electrical components, choose the correct statement out of the following about the diode:

Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: n-p-n transistor permits more current than a p-n-p transistor.
Reason R: Electrons have greater mobility as a charge carrier.
Choose the correct answer from the opt …

The TV transmission tower at a particular station has a height of 125 m. For doubling the coverage of its range, the height of the tower should be increased by :

The positive feedback is required by an amplifier to act an oscillator. The feedback here means :

A sinusoidal wave $\mathrm{y}(\mathrm{t})=40\sin \left(10\times 10^6\pi \mathrm{t}\right)$ is amplitude modulated by another sinusoidal wave $x(t)=20\sin (1000\pi t)$. The amplitude of minimum frequency component of modulated signal is :

Only $2\%$ of the optical source frequency is the available channel bandwidth for an optical communicating system operating at 1000 nm . If an audio signal requires a bandwidth of 8 kHz , how many channels can be accommodated for transmission :

A transistor is used in an amplifier circuit in common emitter mode. If the base current changes by $100\mu \mathrm{A}$, it brings a change of 10 mA in collector current. If the load resistance is $2\mathrm{k}\Omega$ and input resistance is $1\mathrm{k}\Omega$, the value of …

The I-V characteristics of a p-n junction diode in forward bias is shown in the figure. The ratio of dynamic resistance, corresponding to forward bias voltages of 2 V and 4 V respectively, is :

Choose the correct statement for amplitude modulation:

Identify the correct Logic Gate for the following output $(\mathrm{Y})$ of two inputs A and B .

Find the modulation index of an AM wave having 8 V variation where maximum amplitude of the AM wave is 9 V .

If the potential barrier across a p-n junction is 0.6 V. Then the electric field intensity, in the depletion region having the width of $6\times 10^{-6}\text{m}$, will be ______ $\times 10^5\text{N}/\text{C}$.

A transistor is used in common-emitter mode in an amplifier circuit. When a signal of 10 mV is added to the base-emitter voltage, the base current changes by $10\mu \mathrm{A}$ and the collector current changes by 1.5 mA. The load resistance is $5\mathrm{k}\Omega$. The voltag …

In an experiment of CE configuration of n-p-n transistor, the transfer characteristics are observed as given in figure.

If the input resistance is $200\Omega$ and output resistance is $60\Omega$ the voltage gain in this experiment will be $\_\_\_\_$

The photodiode is used to detect the optical signals. These diodes are preferably operated in reverse biased mode because:

Identify the logic operation carried out by the given circuit :-

Statement-I: By doping silicon semiconductor with pentavalent material, the electrons density increases.
Statement-II: The n-type semiconductor has net negative charge.
In the light of the above statements, choose the most appropriate answer from the options given below:

An amplitude modulated wave is represented by
$C_m(t)=10(1+0.2\cos 12560t)\sin \left(111\times 10^{4}t\right)$ volts.
The modulating frequency in kHz will be .......

If an emitter current is changed by 4 mA, the collector current changes by 3.5 mA. The value of $\beta$ will be:

An audio signal $V_m=20\sin 2\pi (1500t)$ amplitude modulates a carrier $V_c=80\sin 2\pi (100,000t)$. The value of percent modulation is ______.

Four NOR gates are connected as shown in figure. The truth table for the given figure is:

For the given circuit, the power across zener diode is ______ mW.

A carrier wave $V_C(t)=160\sin \left(2\pi \times 10^{6}t\right)$ volts is made to vary between $V_{\max }=200\mathrm{V}$ and $V_{\text{min }}=120\mathrm{V}$ by a message signal $V_m(t)=A_m\sin \left(2\pi \times 10^{3}t\right)$ volts. The peak voltage $A_m$ of t …

Zener breakdown occurs in a $\mathrm{P}-\mathrm{n}$ junction having P and n both:

Given below are two statements:
Statement I: PN junction diodes can be used to function as transistor simply by connecting two diodes, back to back, which acts as the base terminal.
Statement II: In the study of transistor, the amplification factor β indicates ratio of the collec …

The logic circuit shown above is equivalent to:

A signal of 0.1 kW is transmitted in a cable. The attenuation of cable is -5 dB per km and cable length is 20 km . The power received at receiver is $10^{-x}\mathrm{W}$. The value of x is ____
[ Given in dB …

For the forward biased diode characteristics shown in the figure, the dynamic resistance at ${\mathrm{I}}_{\mathrm{D}}=3\mathrm{mA}$ will be ____ $\Omega$.

A zener diode having zener voltage 8 V and power dissipation rating of 0.5 W is connected across a potential divider arranged with maximum potential drop across zener diode is as shown in the diagram. The value of protective resistance $R_p$ is ______ $\Omega$.

For a transistor $\alpha$ and $\beta$ are given as $\alpha =\frac{{\mathrm{I}}_{\mathrm{C}}}{{\mathrm{I}}_{\mathrm{E}}}$ and $\beta =\frac{{\mathrm{I}}_{\mathrm{C}}}{{\mathrm{I}}_{\mathrm{B}}}$. Then the correct relation between $\alpha$ and $\beta$ will be:

A zener diode of power rating 2 W is to be used as a voltage regulator. If the zener diode has a breakdown of 10 V and it has to regulate voltage fluctuated between 6 V and 14 V , the value of $R_s$ for safe operation should be ____ $\Omega$.

Given below are two statements :
Statement I:A speech signal of 2 kHz is used to modulate a carrier signal of 1 MHz . The bandwidth requirement for the signal is 4 kHz .
Statement II : The side band frequencies are 1002 kHz and 998 kHz .
In the light of the above statements, choo …

A 5 V battery is connected across the points X and Y . Assume ${\mathrm{D}}_1$ and ${\mathrm{D}}_2$ to be normal silicon diodes. Find the current supplied by the battery if the +ve terminal of the battery is connected to point X .

In a given circuit diagram, a 5 V zener diode along with a series resistance is connected across a 50 V power supply. The minimum value of the resistance required, if the maximum zener current is 90 mA be ______ $\Omega$.

The maximum and minimum amplitude of an amplitude modulated wave is 16 V and 8 V respectively. The modulation index for this amplitude wave is $x\times 10^{-2}$. The value of $x$ is ____

For a transistor in CE mode to be used as an amplifier, it must be operated in :

Draw the output signal Y in the given combination of gates.

If the highest frequency modulating a carrier is 5 kHz , then the number of AM broadcast stations accommodated in a 90 kHz bandwidth are ____

The zener diode has a ${\mathrm{V}}_{\mathrm{z}}=30\mathrm{V}$. The current passing through the diode for the following circuit is ____ mA .

If VA and VB are the input voltages (either 5 V or 0 V ) and Vo is the output voltage then the two gates represented in the following circuit (A) and (B) are:-

Statement-I : To get a steady dc output from the pulsating voltage received from a full wave rectifier we can connect a capacitor across the output parallel to the load RL.

Statement-II : To get a steady dc output from the pulsating voltage received from a full wave rectifier we …

A bandwidth of 6 MHz is available for A.M. transmission. If the maximum audio signal frequency used for modulating the carrier wave is not to exceed 6 kHz. The number of stations that can be broadcasted within this band simultaneously without interfering with each other will be _ …

Choose the correct waveform that can represent the voltage across $R$ of the following circuit, assuming the diode is ideal one :

In the following logic circuit the sequence of the inputs $A,B$ are $(0,0),(0,1),(1,0)$ and $(1,1)$. The output Y for this sequence will be :

A transistor is connected in common emitter circuit configuration, then collector supply voltage is 10 V and the voltage drop across a resistor of $1000\Omega$ in the collector is 0.6 V. If the current gain factor $(\beta )$ is 24, then the base current is ______ $\mu \mathrm{A}$. …

The amplitude of upper and lower side bands of A.M. wave where a carrier signal with frequency 11.21 MHz, peak voltage 15 V is amplitude modulate by a 7.7 kHz sine wave of 5 V amplitude are $\frac{a}{10}\mathrm{V}$ and $\frac{b}{10}\mathrm{V}$ respectively. Then the value of …

The output of the given combination gates represents:

In Amplitude Modulation, the message signal $V_m(t)=10\sin \left(2\pi \times 10^{5}t\right)$ volts and carrier signal $V_c(t)=20\sin \left(2\pi \times 10^{7}t\right)$ volts. The modulated signal now contains the message signal with lower side band and upper side band fr …

Identify the logic operation carried out.