JEE Main · 2021 · 20 Jul 2021 · Shift 2 · Semiconductors

For the forward biased diode characteristics shown in the figure, the dynamic resistance at

I_{D} = 3 mA

will be ____

Ω

Answer: 25

Solution

Dynamic resistance is the reciprocal slope of the forward characteristic at the operating point,

r_{d} = \frac{Δ V _{D}}{Δ I _{D}}

. Near

I_{D} = 3

mA the curve passes through

(0.70 V, 3 mA)

and

(0.75 V, 5 mA)

, so

r_{d} = \frac{0.75 - 0.70}{( 5 - 3 ) \times 1 0 ^{- 3}} = \frac{0.05}{2 \times 1 0 ^{- 3}}

The dynamic resistance at this current is

25 Ω

JEE Main · 2021 · 20 Jul 2021 · Shift 2 · Integer answer