n - type semiconductor contains:

Equal number of holes and electrons

Define N and P - type semiconductors. Explain the working of P - N junction diode with circuit diagram in forward bias and reverse bias.

N-type Semiconductor An extrinsic semiconductor which has been doped with electron donor atoms is called an n-type semiconductor, because the majority of charge carriers in the crystal are negative electrons. P-type Semiconductor An extrinsic semiconductor which has been doped with electron acceptor atoms is called a p-type semiconductor. Crystal doped with group III elements is the p-type semiconductor. Radiation Dosimetry. Working of P-N junction diode A P-N junction diode is said to be forward biased when the positive terminal of a cell or battery is connected to the p-side of the junction and the negative terminal to the n side. When diode is forward-biased the depletion region narrows and consequently, the potential barrier is lowered. This causes the majority charge carriers of each region to cross into the other region. The electrons travel from the n-side to the p-side and go to the positive terminal of the battery. The holes that travel from the p-side to the n-side combine with the electrons injected into the n-region from the negative terminal of the battery. This way the diode conducts when forward-biased. Reverse-biased pn junction diode A pn-junction diode is said to be reverse biased when the positive terminal of a cell or battery is connected to the n-side of the junction and the negative terminal to the p-side. When reverse biased, the depletion region widens and the potential barrier is increased. The polarity of the battery extracts the majority charge carriers of each region. The holes in the p-region from the electrons injected into the p-region from the negative terminal of the battery. The electrons in the n-region go to the positive terminal of the battery. This way, the majority charge carrier concentration in each region decreases against the equilibrium values and the reverse biased junction diode has a high resistance. Thus, the diffusion current across the junction becomes zero. Thus, the diode does not conduct when reverse biased and is said to be in a quiescent or non-conducting state i.e., it acts as an open switch. Forward Bias: Reverse Bias:

What are logic gates? Write symbols and truth table for OR, AND, NOT and NAND gates.

Logic Gates: Logical circuit in which logical relationship exists between inputs and outputs are called logic gate. 1. OR Gate: OR gate having two inputs point and one output. Symbol Truth table: A B Y=A+B 0 0 0 0 1 1 1 0 1 1 1 1 2. AND Gate: AND gate having two input and one output. Symbol Truth Table: A B Y=A.B 0 0 0 0 1 0 1 0 0 1 1 1 3. NOT Gate: Not gate having only one input and one output. Symbol: Truth Table: A Y = A ¯ 0 1 1 0 4. NAND Gate: NAND gate is constructed on applying NOT gate beyond AND gate. Symbol: Truth Table: A B Y = A · B ¯ 0 0 1 1 0 1 0 1 1 1 1 0

A transducer is a device that does transduction i.e. conversion of one form of energy into another. As we know, there are many energy types like chemical, electrical, thermal, mechanical, electromagnetic, acoustic, etc. They can be interconverted as per requirement. Any form of energy can be made as an input. Some of the common examples of transducers that we see around us are loudspeaker, image sensor etc. Mainly there are two types of transducer which are mechanical transducer and electronic transducer. Electronic transducers are more often used in a communication system. Mechanical transducer- They convert a physical form of energy to mechanical forms whereas electronic transducer converts mechanical forms to electrical quantity, mainly into signals. Based on the direction of information the transducer can be a sensor or actuator. A sensor responds to physical stimuli and passes information in the form of a signal accordingly. An actuator is controlled by signal and it converts energy to motion. The robot control system is an example. In the electronic communication system, the transducer is of great importance. They convert various other forms into electric signals. Some of the most commonly used transducers are microphones, speakers, radio transmitters etc...