The voltmeter is
connected across the
resistor, to measure the
voltage across the
resistor.
The ammeter is connected
in series with the
resistor, to measure the
current flowing around
the circuit and through
the resistor.
Mr Ohm discovered that
if you double the
voltage across the
resistor then the
current through it
doubles.
If you halve the voltage
then the current is
halved.
This means that the
current is PROPORTIONAL
to the voltage.
He also found that if
you double the value of
the resistor then the
current through it is
halved.
If the value of the
resistor is halved the
the current is doubled.
Thus the current is
INVERSELY PROPORTIONAL
to the resistance.
To use the VIR triangle
place your finger over
the value you wish to
find.
If you wish to find V
then multiply I by R.
If you wish to find I
then divide V by R. |