Question

What is the formula for Ohm's Law? What units are used to express current? What units are used to express potential difference?

Answer 1

I'm going to separate these questions into 3 sections

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First section:

Ohm's Law:

$\text{V=IR}$

$V=\text{voltage}$

$I=\text{current}$

$R=\text{resistance}$

What is the statement of Ohm's Law?

The current through a conductor between two points is directly proportional to the voltage across the two points.

When you have a current running through a conductor between two points, its value can be calculated if one knows the voltage and the resistance, since the current is proportional to the coltage, and the resistance is the constant of proportionality. This law can be simplified into one nifty equation:

$I=\frac{V}{R}$ , where $I$ I  is the current through the conductor in amperes, $V$  is the voltage measured across the conductor in units of volts, and $R$  is the resistance of the conductor in units of ohms. Additionally, Ohm's law states that $R$ is constant and independent of the current.

For example, if we have a circuit which has a resistance $(R)$  of 2, and voltage $(V)$  of 2, we can plug these values into the equation to find the current, which is

$I=\frac{2}{2}$

$I=1$ amp

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Second Section:

Basic form: Current = Flow

Ampere (or amp) is the international unit of a current. It is used to express the quantity of of electrons that are flowing through or past a point in a circuit over a specific/certain/given amount of time.

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Third Section

$\text{The SI unit of potential difference is Volt.}$

$\text{Voult}=\frac{\text{Joule}}{\text{Coulumb}}$

Voltage is the SI unit representing potential difference. Where a difference/Energy Gap occurs, a potential difference is generated. Because energy flows when two different/same sorts of energies are present. Volt was named after scientist Volta, who invented batteries. However, as time passes, the introduction of AC and DC into daily life creates a unit for measuring potential difference, which produces energy flow. Energy creates pressure, which causes the current to flow. With a phase angle of 180 degrees, a potential difference exists between Line and Neutral. However, in a three-phase universe, the angle between phases is 120 degrees.

Less Contextual:

• Potential Difference, PD has same dimension as Voltage.
• Voltage is a derived Quantity and has the unit of volt.
• V = Workdone/Charge
• Workdone = Force*distance
• Force = Mass*distance/time^2
• therefore, Workdone = Mass*distance^2/time^2
• V = Mass*distance^2/(time^2 * Charge)
• V = kg.m^2/(s^2 *c ) = volt
• kg = kilogram
• m = metre
• s = seconds
• c = columb