## Electric Charge

Electric charge is the physical property of matter due to which it experiences a force when placed in an electromagnetic field. Positive and negative electric charges are two types of charge that are usually carried by the charge carriers, protons, and electrons. Energy is created by the movement of charges.

Depending on the environment or surroundings in which the charge is placed, the energy produced can be thermal energy, chemical energy, or electrical energy.

## Electric Current

It is simply the flow of electrons. A continuous flow of electrons or charged particles can be called a current. It is indicated by I or i. The standard unit is the ampere, denoted by A. One ampere of current represents one coulomb (6.24 x 1018 charge carriers) of electric charge moving through a specific point in one second. Physicists consider current to flow from relatively positive points to relatively negative points; This is called the traditional current or the Franklin current. Electrons, the most common charge carrier, are negatively charged. They flow from relatively negative points to relatively positive points. It can be alternating current AC or direct current DC.

### Difference between DC Direct Current and AC Alternating Current

Electric current can be either direct or alternating. Direct current (DC) flows in the same direction at all points in time, although the instantaneous magnitude of the current may vary. In an alternating current (AC), the flow of charge carriers periodically reverses direction. Frequency is the number of complete AC cycles per second, measured in hertz. An example of pure DC is the current produced by an electrochemical cell.

## Electric Voltage

This is the potential difference When there is a difference in potential between two points, the voltage measured between those two points is said to be the difference. It is measured in volts.

Voltage (also known as electric potential difference, electromotive force emf, electric pressure, or electric stress) is defined as the electric potential difference per unit charge between two points in an electric field. Voltage is expressed mathematically (in formulas) using the symbol “V” or “E”. It can be AC or DC.

### Difference between DC and AC Voltage

The direction of DC voltage remains constant with time whereas the direction of AC voltage changes with time.

## Resistance

Resistance is a measure of the opposition to the flow of current in an electrical circuit also known as ohmic resistance or electrical resistance. Ohm is measured as resistance, whose symbol is the Greek letter omega (Ω). The ratio of the applied voltage to the current through the material is then known as resistance. It is denoted by R.

# Ohm’s Law

Ohm’s law is one of the most fundamental laws for electrical and electronic circuits. It deals with current, voltage, and resistance.

**According to Ohm’s law, the potential difference in an ideal conductor is proportional to the current flowing through it**.

**V α I**

An ideal conductor has no resistance. But in practice, each conductor has some resistance. As the resistance increases, the potential drop also increases and so does the voltage.

Hence the voltage is directly proportional to the resistance it provides.

**V α R**

**V = IR**

But current is inversely proportional to resistance

**V α I α 1/R**

**V = I/R**

Therefore, in practice, Ohm’s law can be stated as:

According to Ohm’s law, the current flowing through a conductor is proportional to the potential difference across it and inversely proportional to the resistance it provides.

This rule is helpful in finding the values of unknown parameters out of the three which help in analyzing the circuit.

**Ohm’s law formula for current, voltage, and resistance**

Ohm’s law can be expressed mathematically as:

- For Electric Current

**V = IR**

**Where:**

V = Voltage expressed in volts.

I = Current expressed in Amps.

R = Resistance expressed in Ohms.

- For Electric Voltage

**I = V/R**

- Resistance

**R = V/I**