1

### JEE Main 2016 (Online) 10th April Morning Slot

The ratio (R) of output resistance r0, and the input resistance ri in measurements of input and output characteristics of a transistor is typically in the range:
A
R ~ 102 $-$ 103
B
R ~ 1 $-$ 10
C
R ~ 0.1 $-$ 0.01
D
R ~ 0.1 $-$ 1.0

## Explanation

R $=$ ${{{r_0}} \over {{r_i}}} \equiv 1 - 10$
2

### JEE Main 2016 (Online) 10th April Morning Slot

A realistic graph depicting the variation of the reciprocal of input resistance in an input characteristics measurement in a commonemitter transistor configuration is :
A
B
C
D

## Explanation

For common emitter configuration, the input characteristic graph is shown above,

ri $=$ ${{\Delta {V_{BE}}} \over {\Delta {{\rm I}_B}}}$

$\Rightarrow$   ${1 \over {{r_i}}} = {{d{{\rm I}_B}} \over {d{V_{BE}}}}$ $=$ shope of this curve.

Upto knee voltage 0.7 V the shope is almost constant. Then it increases sharply.

So, option (c) is the correct choice.
3

### JEE Main 2016 (Online) 10th April Morning Slot

To get an output of 1 from the circuit shown in figure the input must be :

A
a = 0, b = 1, c = 0
B
a = 1, b = 0, c = 0
C
a = 1, b = 0, c = 1
D
a = 0, b = 0, c = 1

## Explanation

Here,

Y = c . (a + b)

Now  Y = 1   when,

c = 1 and (a = 1, b = 0 or a = 0, b = 1 or a = 1, b = 1)
4

### JEE Main 2017 (Offline)

In a common emitter amplifier circuit using an n-p-n transistor, the phase difference between the input and the output voltages will be:
A
180°
B
45°
C
90°
D
135°

## Explanation

In common emitter configuration for n-p-n transistor input and output signals are 180° out of phase i.e., phase difference between output and input voltage is 180°.