Q40 of 40 Page 93

In the circuit shown in Fig.14.20, find the value of R_C.

We can simplify the circuit as follows.

We can replace the branch having 100k and 20k resistance with a resistance and a source of some potential. 100k and 20k resistances are in parallel if we short all the voltage sources. Hence, the equivalent resistance will be,

The potential source should constitute the same potential as in the base terminal. So, it is basically going to be the voltage drop across 20k resistance.

So, it will be,

Also, I_E = I_B + I_c and I_c = βI_B

From loop1,

Now, from loop2,

Putting the values of R_E we can find R_C.

More from this chapter

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Suppose a ‘n’-type wafer is created by doping Si crystal having 5 × 10²⁸ atoms/m³ with 1ppm concentration of As. On the surface 200 ppm Boron is added to create ‘P’ region in this wafer. Considering n_i = 1.5 × 10¹⁶ m^–3, (i) Calculate the densities of the charge carriers in the n & p regions. (ii) Comment which charge carriers would contribute largely for the reverse saturation current when diode is reverse biased.

An X-OR gate has following truth table:

It is represented by following logic relation

Build this gate using AND, OR and NOT gates.

Consider a box with three terminals on top of it as shown in Fig.14.18 (a):

Three components namely, two germanium diodes and one resistor are connected across these three terminals in some arrangement.

A student performs an experiment in which any two of these three terminals are connected in the circuit shown in Fig. 14.18 (b).

The student obtains graphs of current-voltage characteristics for unknown combination of components between the two terminals connected in the circuit.

The graphs are

(i) when A is positive and B is negative