While doing revision, I've come across aspects on circuits which I cannot get my head around. May I have some help with these questions and ideas. What's a variable voltage and how do we draw it on a circuit? Does it have a different symbol to a voltmeter? Why does touching the leads together allow the voltmeter to be zeroed? Can I say that it discharges it. In the mark scheme, it says that it is short-circuited, is that the same as being discharged? When using ohmmeter, the resistance of a resistor should not be measured while it is in a circuit. Is it that this will cause the circuit to short-circuit because there are too many component to the circuit? I'm getting confused. Please guide me in the right direction and clear my confusion. Thanks in advance.