In the circuit shown in the figure, find the current passing through `r_L` and zener diode.

Explanation

E=10V
Voltage across Zener diode `=V_(Z)= 5V`
`R_(L)= 100Omega, R= 80Omega`
`I= I_(1) + I_(2)` (By Kirchoff.s first law) `I= (E-V_(Z))/(R )= (10-5)/(80)= (1)/(16)A`
`because` Potential drop across Zener diode `V_(Z)` is equal to potential drop across `R_(L)`.
`therefore V_(Z)= I_(1) R_(L)`
Current through `R_(L), I_(1)= (V_(Z))/(R_(L))= (5)/(100)= (1)/(20)A`
Current through Zener diode `= I_(2)= I- I_(1)`
`=(1)/(16)- (1)/(20)= (1)/(80)A= 0.013A`