1

### JEE Main 2019 (Online) 10th January Evening Slot

For the circuit shown below, the current through the Zener diode is -

A
5 mA
B
zero
C
14 mA
D
9 mA

## Explanation

Assuming zener diode doesnot undergo breakdown, current in circuit

= ${{120} \over {15000}}$ = 8mA

$\therefore$  Voltage drop across diode

= 80 V > 50 V.

The diode undergo breakdown.

Current is R1 = ${{70} \over {5000}}$ = 14mA

Current is R2 = ${{50} \over {10000}}$ = 5mA

$\therefore$  Current through diode = 9mA
2

### JEE Main 2019 (Online) 11th January Morning Slot

In the given circuit the current through Zener Diode is close to:

A
0.0 mA
B
6.7 mA
C
4.0 mA
D
6.0 mA

## Explanation

Since voltage across zener diode must be less than 10V therefore it will not work in breakdown region, & its resistance will be infinite & current through it = 0
3

### JEE Main 2019 (Online) 11th January Evening Slot

The circuit shown below contains two ideal diodes, each with a forward resistance of 50 $\Omega$. If the battery voltage is 6 V, the current through the 100 $\Omega$ resistance (in Amperes) is :

A
0.027
B
0.030
C
0.036
D
0.020

## Explanation

I = ${6 \over {300}}$ = 0.02 (D2 is in reverse bias)
4

### JEE Main 2019 (Online) 12th January Morning Slot

The output of the given logic circuit is :

A
$\overline A B$
B
$AB + \overline {AB}$
C
$A\overline B + \overline A B$
D
$A\overline B$

## Explanation

Y $= \overline {\left( {\overline A + \overline B } \right)\overline A }$

$= \overline {\overline A + \overline A B}$

$= A\left( {\overline {\overline A B} } \right)$

$= A\left( {A + \overline B } \right)$

$= A + A\overline B = A\overline B$