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 fo `100` milliwatts. What should be the value of the resistor `R`, connected in series with the diode for obtaining maximum current?

Explanation

Voltage drop across diode, `V=0.5 V`
Maximum power rating,
`P=100mW=100xx10^(-3)W=0.1 W`
Current, `I=P/V=0.1/0.5=1/5A`
`E-V=IR or R=(E-V)/I=(1.5-0.5)/(1//5)=5Omega`