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A zener diode with 5 V zener voltage is used to regulate an unregulated dc voltage input of 25 V. For a 400 Ω resistor connected in series, zener current is found to be 4 times load current. The load current (I_L) and load resistance (R_L) are:
- I_L = 20 mA; R_L = 250 Ω
- I_L = 0.02 mA; R_L = 250 Ω
- I_L = 10 mA; R_L = 500 Ω
- I_L = 10 A; R_L = 0.5 Ω
Correct answer: I_L = 10 mA; R_L = 500 Ω
Solution
The correct option is right because if the zener current is four times the load current, and the total current through the resistor is the sum of the load current and the zener current, we can derive that the load current must be 10 mA to satisfy the given conditions, leading to a load resistance of 500 Ω when using Ohm's law.
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