# Did my teacher make a mistake? (Kirchoff's Rules)

Consider the electric circuit shown in the figure. Using Kirchhoff's rules, select True or False for the following equations.

a.) I2 + I3 = I1
b.) ε1 - I2R2 - I3R3 - I1R1 = 0
c.) ε2 - I1R5 - I3R3 - I2R4 = 0

http://tinypic.com/r/2zyws55/8

My answers were: True, False, False.

However, the homework systems answers are False, False, False...

How is 'a' false??? Anyone??

berkeman
Mentor
Consider the electric circuit shown in the figure. Using Kirchhoff's rules, select True or False for the following equations.

a.) I2 + I3 = I1
b.) ε1 - I2R2 - I3R3 - I1R1 = 0
c.) ε2 - I1R5 - I3R3 - I2R4 = 0

http://tinypic.com/r/2zyws55/8

My answers were: True, False, False.

However, the homework systems answers are False, False, False...

How is 'a' false??? Anyone??

You could save us a *whole* lot of work if you would post the KCL equations you wrote for this circuit. That way we don't have to spend the time to write them out for ourselves and try to interpret why you answered the way you did. The more work you show us, the better and faster help you will get here.

a.) I2 + I3 = I1

How is 'a' false??? Anyone??

you should be able to tell us why you think a.) is true.

According to Kirchhoff's current law, the current entering a junction, is equal to the current leaving a junction.
Look at the top junction. What's the current entering it and leaving it? Does setting those currents equal produce a.) ?

I got it! Dumb mistake on my part