The junction diode in the following circuit requires a minimum current of `1 mA` to be above the knee point `(0.7 V)` of its `I-V` characterstic curve. The voltage across the diode is independent of current above the knee point. If `V_(B)=5 V`, then the maximum value of `R` so that the voltage is above the knee point, will be

Options

A. `4.3 k Omega`
B. `860 k Omega`
C. `4.3 Omega`
D. `860 Omega`

Answer

A

Explanation

At knee point voltage across the diode is `0.7 V`.
Hence voltage across resistance `R` is `5-0.7=4.3V`.
`implies` Using `V=iR implies 4.3=1xx10^(-3)xxR implies 4.3 kOmega`.