Question

A cell of emf $4.5V$ is connected to a junction diode whose barrier potential is $0.7V$. If the external resistance in the circuit is $190$$\Omega$, the current in the circuit is

• A. $20mA$
• B. $2mA$
• C. $23mA$
• D. $200mA$

Answer 1

The correct option is A $20mA$

$E=4.5V$
$V_D=0.7V$
$R=190\Omega$
The current through the circuit is
$I=\frac{E-V_D}{R}$

$I=\frac{4.5-0.7}{190}=0.02A=20mA$