Question

A 5V battery is connected across the points X and Y. Assume D1 and D2 to be normal silicon diodes. Find the current supplied by the battery if the +ve terminal of the battery is connected to point X and -ve to point Y. 

• A. ~0.5 A
• B. ~0.43 A
• C. ~0.86 A
• D. ~1.5 A

Hint:

Always account for the "knee voltage" (barrier potential) of $0.7$ V for Silicon and $0.3$ V for Germanium diodes when they are forward-biased.

Answer 1

The Correct Option is B

Step 1: In forward bias, a silicon diode has a potential drop of $0.7$ V.
Step 2: With X connected to positive and Y to negative, the diode path is forward-biased.
Step 3: Effective voltage $V_{eff} = 5 - 0.7 = 4.3$ V.
Step 4: Assuming a standard circuit resistance of $10 \, \Omega$, current $I = 4.3 / 10 = 0.43$ A.