NCERT Solutions for Chapter: Semiconductor Electronics: Materials, Devices and Simple Circuits, Exercise 3: SA

(i) Name the type of a diode whose characteristics are shown in Fig. $\left(\mathrm{A}\right)$ and Fig. $\left(\mathrm{B}\right)$.

(ii) What does the point $\mathrm{P}$ in Fig. $\left(\mathrm{A}\right)$ represent?

(iii) What does the points $\mathrm{P}$ and $\mathrm{Q}$ in Fig. $\left(\mathrm{B}\right)$ represent?

Three photo diodes $D_1, D_2$ and $D_3$ are made of semiconductor having band gaps of $2.5\mathrm{eV}, 2\mathrm{eV}$ and $3\mathrm{eV}$, respectively. Which ones will be able to detect light of wavelength $60000 \stackrel{\mathrm{o}}{\mathrm{A}}$?

If the resistance ${\mathrm{R}}_i$ is increased in the given figure, how will the readings of the ammeter and voltmeter change?

Two car garages have a common gate which needs to open automatically when a car enters either of the garages or cars enter both. Devise a circuit that resembles this situation using diodes for this situation.

How would you set up a circuit to obtain NOT gate using a transistor?

Explain why elemental semiconductor cannot be used to make visible $\mathrm{LEDs}$.

Write the truth table for the circuit shown in figure. Name the gate that the circuit resembles.

A Zener of power rating $1 \mathrm{W}$ is to be used as a voltage regulator. If zener has a breakdown of $5\mathrm{V}$ and it has to regulate voltage which fluctuated between $3\mathrm{V}$ and $7\mathrm{V}$, what should be the value of $R_s$ for safe operation ?