The value of power dissipated across the zener diode ( $\mathrm{V}_{\mathrm{z}}=15 \mathrm{~V}$ ) connected in the circuit as shown in the figure is $\mathrm{x} \times 10^{-1}$ watt. The value of x , to the nearest integer, is ____

JEE Main · 2021 · 16 Mar 2021 · Shift 1 · Current Electricity

The value of power dissipated across the zener diode (

V_{z} = 15 V

) connected in the circuit as shown in the figure is

x \times 1 0^{- 1}

watt.
The value of x , to the nearest integer, is ____

Answer: 5

The zener holds its own terminals, and therefore the load, at

V_{z} = 15

V. The remaining

22 - 15 = 7

V appears across the series resistor, so the current drawn from the supply is

I = \frac{7}{35} = 0.2 A

The load takes

I_{L} = \frac{15}{90} = \frac{1}{6} A

, and whatever the load does not take passes through the diode:

I_{Z} = 0.2 - \frac{1}{6} = \frac{1}{30} A

The power dissipated in the zener is

P = V_{z} I_{Z} = 15 \times \frac{1}{30} = 0.5

W, which is

5 \times 1 0^{- 1}

W, so

x = 5

JEE Main · 2021 · 16 Mar 2021 · Shift 1 · Integer answer