COMEDK 2023 Shift 1 Paper

To find the reverse resistance of the junction diode given the change in reverse current and reverse potential, we use the formula for resistance:
R=‌

V

I

However, since we're dealing with changes in voltage (∆V) and current (∆I), the resistance (specifically, the dynamic or incremental resistance) can be calculated as:
R=‌

∆V

∆I

Given:
Change in reverse potential, ∆V=15V−10V=5V
Change in reverse current, ∆I=40µA−20µA=20µA
First, let's convert the change in current to amperes (A) because the resistance will be calculated in terms of volts per ampere.
20µA=20×10−6A
Now, we'll substitute the values into the formula:
‌R=‌

5V

20×10−6A

‌R=‌

5

20×10−6

‌R=250,000Ω
‌R=250kΩ
Therefore, the reverse resistance of the junction diode is 250kΩ, which corresponds to Option A.