Please explain OHM's "Law"

Question

anonymous · Answer

R=U/I

anonymous · Answer

"Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points. Introducing the constant of proportionality, the resistance,"-from Wikipedia

In mathematical terms this means:$$I=\frac{V}{R}$$
Where I - current, V - voltage across the resistor, R - resistor

In other words, given the voltage (V) across the resistor (R) you can determine the current that is passing through the resistor,
or, given voltage(V) across the resistor and current(I) through the resistor you can figure out the value of R. And the same for determining V.

anonymous · Answer

It's strange that we use U rather than V in China

anonymous · Answer

also, pls explain why electric field is directly proportional with the current density?

anonymous · Answer

Let's prosume a uniform electric field.E=electric field And E=V(which we use U in China)/d  the current I=q/t ;the current density J=I/S(area).So we can learn that E=r*J*S/d

anonymous · Answer

Yea U is used for voltage in Croatia too.

anonymous · Answer

v=i*r where i=current r=resistence