Semiconductors — JEE Main PYQs

A signal of 5 kHz frequency is amplitude modulated on a carrier wave of frequency 2 MHz . The frequencies of the resultant signal is/are:

The forward biased diode connection is:

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 which could be detected by it.

The I-V characteristic of an LED is

Truth table for system of four NAND gates as shown in figure is

A radar has a power of 1 kW and is operating at a frequency of 10 GHz. It is located on a mountain top of height 500 m. The maximum distance upto which it can detect object located on the surface of the earth (Radius of earth $=6.4\times 10^6$ m) is

The combination of gates shown below yields

A p-n junction (D) shown in the figure can act as a rectifier. An alternating current source ($\mathrm{V}$) is connected in the circuit.

The logic circuit shown below has the input waveforms 'A' and 'B' as shown. Pick out the correct output waveform.

A working transistor with its three legs marked $\mathrm{P},\mathrm{Q}$ and R is tested using a multimeter. No conduction is found between P and Q . By connecting the common (negative) terminal of the multimeter to R and the other (positive) terminal to P or Q , some resistanc …

In the circuit below, A and B represent two inputs and C represents the output. The circuit represents

If in a p-n junction diode, a square input signal of 10 V is applied as shown, then the output signal across $R_L$ will be

Carbon, silicon and germanium have four valence electrons each. At room temperature which one of the following statements is most appropriate?

A solid which is transparent to visible light and whose conductivity increases with temperature is formed by

If the ratio of the concentration of electrons that of holes in a semiconductor is $\frac{7}{5}$ and the ratio of currents is $\frac{7}{4}$, then what is the ratio of their drift velocities?

In a common base mode of a transistor, t collector current is 5.488 mA for an emit current of 5.60 mA. The value of the base current amplification factor $(\beta )$ will be

If the lattice constant of this semiconductor is decreased, then which of the following is correct?

In the following, which one of the diodes is reverse biased?

The circuit has two oppositely connect ideal diodes in parallel. What is the current following in the circuit?

In a common base amplifier, the phase difference between the input signal voltage and output voltage is

In a full wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be

When npn transistor is used as amplifier

For a transistor amplifier in common emitter configuration having load impedance of $1\text{ k}\Omega$ ($h_{fe}=50$ and $h_{oe}=25\mu \mathrm{S}=25\times 10^{-6}{\Omega }^{-1}$) the current gain is

The manifestation of band structure in solids is due to

When p-n junction diode is forward biased