A diode made of silicon has a barrier potential of `0.7 V` and a current of `20 mA` passes through the diode when a battery of `emf 3 V` and a resistor is connected to it. The wattage of the resistor and diode are

Options

A. `0.046 W, 0.014 W`
B. `4.6 W,0.14 W`
C. `0.46 W,0.14 W`
D. `46 W,14 W`

Answer

A

Explanation

`P = VI` (for resistor)
`=(3-0.7)20 xx 10^(-3) = 2.3 xx 20 xx 10^(-3)`
`= 46 xx 10^(-3) = 0.046 W`
for diode, `P = 0.7 xx 20 xx 10^(-3) = 0.014 W`.