Draw here the circuit diagram of a circuit composed of a voltage source, a resistor, an ammeter measuring the resistance current and a voltmeter measuring the resistor voltage. The voltmeter must be connected directly across the resistor: its internal resistance is very high $(10$ M$)$ so that the current through it is negligible. The internal resistance of an ammeter, on the other hand, cannot always be neglected with respect to the value of the resistor used. If you then measure the voltage across the series circuit of ammeter and the resistor, you would find a too high value.Indicate the polarity for every component, including the meters.