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The 6 V zener diode shown in figure has zero zener resistance and a knee current of 5 mA. The minimum value of R so that voltage across it does not fall below 6 V is—
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- 1.2 kΩ
- 80 Ω
- 50 Ω
- 0 Ω
Correct Option: B
Given that IZ (knee current) = 5 mA 
| I = | = | | 50 | 50 |
I = 80 mA
IR = I – IZ = 80 – 5 = 75 mA
| R = | = | = | = 80 Ω. | IR | 75 x 10-3 | 75 |
Hence alternative (B) is the correct answer.
