How is the current controlled for a given voltage

The current can be controlled by modifying the resistance value

Explanation:

The current can be controlled by modifying the resistance value, usually a variable resistance device called potentiometer is used. This can be observed mathematically using the ohm law which is defined as voltage equal to the current product by resistance.

V = I*R

where:

I = current [amp]

R = resistance [ohm]

V = voltage [volt]

We can see that if we reduce the resistance the current will be increased

I = v / R

And if we amplify the resistance (R) the current will be diminished