This isn't a homework question but it is a formula from a book I have been using to study, so I'm posting it here.(adsbygoogle = window.adsbygoogle || []).push({});

Here is the circuit and formula -

I don't understand why the voltage drop of 0.7 volts across the diode is being used as part of the formula to work out the current across R2 when R2 has it's own voltage drop across it. Can someone explain this to me please?

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

Join Physics Forums Today!

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

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

# Homework Help: Help needed with a diode and resistor formula

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