I've been looking into this topic quite a bit and I think I have figured it out. However, I would like to clarify with someone who actually knows what they're talking about.
I know ohm's law is V = IR
Though I found this circuit in a physics question:
The question asked what would happen to the current and voltage in the fixed resistor if the resistance in the variable resistor increased.
Since R = V/I,
you may think the voltage increases and the current decreases. However, the answer in the mark scheme stated both the voltage and the current decreased.
I asked my teacher about this and he said that because the resistance in the variable resistor increased, the voltage in the variable resistor increased. Therefore the voltage in the fixed resistor decreased as the total voltage remains constant. The current decreasing is fairly obvious though.
However, I was wondering what would happen in a parallel circuit like the one in the diagram below:
I read that in a parallel circuit, all the branches have equal voltage. So if I increase the resistance on the variable resistor, the voltage should remain the same on both the variable and fixed resistor. However, the current changes between the barnches in a parallel circuit. If the resistance was higher in the branch with the variable resistor, then by ohm's law the current is lower. Since the total current is conserved at a junction in a parallel circuit, the current in the branch with the fixed resistor should increase.
This question turned out to be longer than I thought.
I will appreciate clarification as to whether this is correct as I have an physics exam tomorrow.