Semiconductor Electronics Materials Devices And Simple Circuits

Step 1: Understanding the Question:
We are given a logic circuit made of four NOR gates and two inputs, A and B. We need to find the truth table for the final output Y.
Step 2: Key Formula or Approach:
We will trace the logic signals through the circuit for each possible input combination (00, 01, 10, 11). The Boolean expression for a NOR gate with inputs X and Z is .
Step 3: Detailed Explanation:
Let's label the intermediate outputs.
- The output of the top-left NOR gate (inputs A, B) be . - The output of the middle NOR gate (inputs A, ) be . - The output of the bottom NOR gate (inputs B, ) be . - The output of the final NOR gate (inputs , ) is Y. Let's simplify this using Boolean algebra:
First, simplify and . Using De Morgan's theorem ( ):
Now, substitute these into the expression for Y:
The expression is the definition of the XOR operation ( ).
Therefore, , which is the XNOR operation.
Let's construct the truth table for Y = XNOR(A, B):
- If A=0, B=0:
- If A=0, B=1:
- If A=1, B=0:
- If A=1, B=1:
Step 4: Final Answer:
The resulting truth table is:
This matches the truth table in option (A).

The correct answer is (A) : Both A and Rare true, and R is correct explanation of A.
(A) is true as n-p-n transistor permits more current than p-n-p transistor as electrons which are majority charge carriers in n-p-n have higher mobility than holes which are majority carriers in
p-n-p transistor

The correct answer is (C) :

The shown circuit is a combination of AND gate and a NOT gate.

The correct answer is (B) : It is two terminal device which conducts current in one direction only.
A diode is a two terminal device which conducts current in forward bias only.

The correct answer is 14
Conserving energy,




⇒ x = 14
There , the speed will be 14 m/s

The correct answer is

The correct answer is 25

3

Solution:
Using the formula for the current through the conductor, which relates the current at different temperatures: This gives: Now, calculate : Thus, the current at 50°C will be: Substituting values: Thus, the current at 50°C is . Therefore, the correct answer is .

To solve this problem, we'll start by understanding the setup and conditions given:

The Wheatstone bridge is balanced initially, with arm BC, made of semiconductor, having an initial resistance at . This arm is cooled at . If the galvanometer shows no deflection after 10 seconds, the bridge remains balanced, and the resistance change condition can be expressed as follows:

The temperature change in 10 seconds is:

Let be the temperature coefficient of resistivity. The change in resistance will be:

For the bridge to remain balanced:

The initial configuration has resistance and . In the balanced condition:

The change in resistance should satisfy:

Initially, and after 10s.

Let's substitute the known values:

Re-arranging gives:

This simplifies to:

Therefore, the temperature coefficient of resistivity is:

, which matches option .

To determine the wavelength of light emitted from the LED, we need to understand the relationship between the energy of a photon and its wavelength. The energy of a photon is given by the equation:

Where:

• is the energy of the photon, measured in electron volts (eV).
• is Planck's constant, approximately .
• is the speed of light in vacuum, approximately .
• is the wavelength of the emitted light, measured in meters.

The band gap energy of GaAs (Gallium Arsenide) is given as . This energy corresponds to the energy of the photons emitted from the LED.

We will rearrange the equation to solve for wavelength :

Substitute the known values into the equation:

Calculate the wavelength:

Convert meters to nanometers (1 m = 10⁹ nm):

The wavelength of the light emitted from the LED is approximately .

This calculation matches the correct answer, which is .

Therefore, the correct answer is 875 nm.

To solve this problem, we need to determine the maximum wavelength of light that can create a hole in a p-type semiconductor with an acceptor level of 6 eV. This involves using the relationship between energy, wavelength, and the quantum nature of light.

The energy of a photon is related to its wavelength via the equation:

where:

• is Planck's constant.
• is the speed of light.
• is the wavelength.

Given that and the acceptor level energy , we need to find the maximum wavelength that can induce transitions corresponding to this energy level.

Re-arranging the formula for wavelength, we get:

Substituting the provided values:

Calculating this gives:

Thus, the maximum wavelength of light that can create a hole in this semiconductor is 207 nm.

Let's justify this answer:

• Option: 407 nm — This option would imply a lower energy than required.
• Option: 414 nm — This option also implies a lower energy than required.
• Option: 207 nm — Correct, as calculated.
• Option: 103.5 nm — This implies higher energy, which isn’t needed to create the hole.

Therefore, the correct answer is 207 nm.

To determine the value of , we need to calculate the band gap energy of the photodiode, given that it starts changing its conductivity when illuminated with light whose wavelength is less than 660 nm.

The energy of a photon is related to its wavelength by the formula:

where:

• is Planck's constant.
• is the speed of light in a vacuum.
• is the wavelength of the incident light.

Substituting these values into the formula, we get:

Calculating the above expression gives:

Simplifying gives:

To convert energy from joules to electron volts, use the conversion factor :

The band gap is given as , so we equate and solve for :

Therefore,

Hence, the value of is 15. Thus, the correct answer is 15.