For the circuit shown in Fig. find
the current through Zener diode.

Explanation

From the figure
`R=5 k Omega = 5 xx 10^3 Omega `
Input voltage `V_("in") = 120 V,`
zener voltage, `V_Z = 50 V `
Load current `I_L =(V_Z )/(R_L ) = ( 50 )/( 10 xx 10^(3)) = 5 xx 10^(-3) A `
Current through `R=i=(V_("in") -V_z)/(R ) `
`=( 70 )/( 5 xx 10^3) = 14 xx 10^(-3) A `
According to the Kirchoff.s first law `I = I_L +I_Z`
` therefore `Zener current,
` I_Z =I-I_L = 14 xx 10^(-3) -5 xx 10^(-3) = 9 xx 10^(-3) = 9 mA `