Question

The diode used in the circuit shown in the figure has a constant voltage drop of 0.5 V at all currents and a maximum power rating of 100 milliwatts. What should be the value of the resistor R, connected in series with the diode for obtaining maximum current

• A. 1.5 Ω
• B. 5 Ω
• C. 6.67 Ω
• D. 200 Ω

Answer 1

Answer: (B)

5 Ω

Answer 2

The current through circuit $i = \frac{P}{V} = \frac{100 \times 10^{- 3}}{0.5} = 0.2A$

∴ voltage drop across resistance = 1.5 – 0.5 = 1 V

⇒ $R = \frac{1}{0.2} = 5\Omega$