Yet another Physics question

The sum of the currents through Q and X must equal the sum of the currents through P and Y

The sum for P and Y is 0.48mA
If they are the correct answers (and the value for Q) then the current through X is 0.48mA - 0.06mA
This gives 0.42mA

I have no way of checking if your answers are correct for the other parts as you have not provided the whole question.

Yes sorry that is the right answer thanks.

is that a rule we must learn? I'm not that familiar with it, it would be great if you could point me to some extra information on that!

It's just common sense.

If the current flowing round the main circuit splits in two, as it does in P and Y, then the sum of the currents in P and Y must equal the main current. Current doesn't disappear.
The current then comes back together and then splits through Q and X.
So the sum of the currents in Q and X must equal the main current in the circuit.

As you have found the currents in P and Y and the sum is 0.48mA, then that is the current flowing round the main circuit and through the battery. So if it splits in Q and X and you know one of those currents (Q), you can find the other.

The rule is that current doesn't disappear at a point where a circuit divides. Some call this Kirchhoff's 1st Circuit Rule.

Thanks. Yeah just read up on it now!


If i could, do you know any easy way of distinguishing between the positive and negative ends of a potential divider?