Question

When a diode is forward biased, it has a voltage drop of 0.5 V. The safe limit of current through the diode is 10 mA. If a battery of emf 1.5 V is used in the circuit, the value of minimum resistance to be connected in series with the diode so that the current does not exceed the safe limit is ______.

Options

• 300 Ω

• 50 Ω

• 100 Ω

• 200 Ω

Answer 1

When a diode is forward biased, it has a voltage drop of 0.5 V. The safe limit of current through the diode is 10 mA. If a battery of emf 1.5 V is used in the circuit, the value of minimum resistance to be connected in series with the diode so that the current does not exceed the safe limit is 100 Ω.

Explanation:

According to question, when diode is forward biased,

`"V"_"diode"` = 0.5 V

Safe limit of current, I = 10 mA = 10^-2 A

`"R"_"min"` = ? 

Voltage through resistance

V_R = 1.5 - 0. 5 = 1 volt

iR = 1 (=V_R)

∴ `"R"_"min" = 1/"i"`

= `1/10^-2`

= 100 Ω