(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Determine the value of the ballast resistor is satisfactory if a 5Volt 0.5 watt zener diode is used in the circuit

sorry cant upload a picture but basically

VS = 15v min to 20v max

R ballast = 90 ohms (series with zener)

and R load (in parralel with Zener) is 50 ohms

2. Relevant equations

max zener current = watts/voltage 0.5/5v= 100Ma

now im getting a bit stuck i keep getting values of 100ohms at min Vs and 150 ohms at max Vs.

will update post later running out of time at the minute

thanks guys

3. The attempt at a solution

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Zener diode ballast resistor question

**Physics Forums | Science Articles, Homework Help, Discussion**