Electric Current

Electric Current

Shiken premium Upgrade Banner

Electricity is a type of energy that happens when charged particles, like electrons, move from one place to another. Everything is made up of atoms that have a nucleus and electrons. The nucleus has particles called neutrons, which have no charge, and protons, which have a positive charge. Atoms that are stable have the same number of protons and electrons to keep a neutral charge.

In some materials, like metals such as copper and silver, the electrons can move freely. The movement of these electrons is called an electric current. Electrical engineering is the field that studies electricity and its uses.

Keywords: Electric current, electricity, charged particles, atoms, electrons, conductors, electrical engineering.

Defining electric current

Electric current is the amount of charge that moves in a given time. To calculate it, we use a formula and specific units.

What's cool is that an electric current creates a magnetic field, and a magnetic field can create an electric current too!

Batch variation

When two charged objects are connected using a conductive wire, a charge flows through them, producing a current. The current flows because the charge difference causes a voltage difference.

Flow of charge in a conductor
Flow of charge in a conductor

Conventional current flow

In a circuit, current refers to the movement of electrons. Electrons are negatively charged, and they move from the negatively charged terminal towards the positively charged terminal. This happens because like charges (negative and negative) repel each other, while opposite charges (negative and positive) attract each other.

However, conventional current is defined as the flow of positive charge from the positive terminal to the negative terminal of the source. This is the opposite of the flow of electrons, which is why the direction of current was initially misunderstood.

Conventional flow vs electron flow
Conventional flow vs electron flow

An important point to make is that the flow of current has a direction and magnitude given in amperes. However, it is not a vector quantity.

How to measure current

To measure current in a circuit, an ammeter is used. It should always be connected in series with the part of the circuit where the current is to be measured. This is because the current has to flow through the ammeter to be measured.

It's important for the ammeter to have an ideal internal resistance of zero, as any resistance would the current in the circuit. there is a voltage present on the ammeter, can also impact the circuit, so it's important to ensure that the ammeter has zero internal resistance.

Arrangement to measure current using Ammeter
Arrangement to measure current using Ammeter

The correct option where 8 mA of current passes through the electrical circuit is option A: When a charge of 4C passes in 500s.

This can be calculated using the formula I = Q/t, where I is current, Q is charge, and t is time.

So, I = 4C / 500s = 0.008A = 8mA.

Hence, option A is the correct answer.

Quantisation of charge

Electric current is the flow of charged particles, such as electrons, from one place to another. The charge on charge carriers is quantized, meaning it occurs in multiples of a specific magnitude, which is the charge of an electron. Charge carriers may be positive or negative, and the current is considered to travel in one direction across the conductor. In a current-carrying conductor, the charge carriers are mostly free electrons, and they move in opposite directions with a drift speed v. The charge carriers’ drift speed is the average speed at which they travel through the conductor. The current in a current-carrying conductor can be mathematically expressed as I = A * n * v * q, where A is the area of the cross-section, n is the number density of charge carriers per m^3, v is the drift velocity in m/s, q is the charge in Coulombs, and I is the current in Amperes. The SI base unit of electric current is amperes (A), and conventional current is described as the flow of positive charge from the cell’s positive terminal to its negative terminal.

Electric Current - Key takeaways Electricity is a form of energy. It is the phenomenon that describes the flow of charged particles (particularly electrons) from one place to another. The SI base unit of electric current is amperes (A). Conventional current is described as the flow of positive charge from the cell’s positive terminal to its negative terminal. The charge on the charge carriers is quantised.

Electric Current

What is electrical current measured in?

Electric current is measured in Amperes (A) or amps.

What is the definition of electric current?

Electric current is defined as the rate of flow of charge carriers.

Do electric currents always produce magnetic fields?

An electric current always produces a magnetic field.

How does a magnetic field create an electric current?

A magnet’s characteristics are utilised to generate electricity. Electrons are pulled and pushed by moving magnetic fields. Electrons in metals like copper and aluminium are scattered throughout. When you move a magnet around a coil of wire, or a coil of wire around a magnet, the electrons in the wire are pushed out and an electrical current is created.

Is electric current a vector quantity?

Electric current is a scalar quantity. Any physical quantity is termed as a vector if it has magnitude, direction and also follows vector laws of addition. Though electric current has magnitude and direction, it does not follow the vector laws of addition. Hence electric current is a scalar quantity.

Join Shiken For FREE

Gumbo Study Buddy

Explore More Subject Explanations

Try Shiken Premium
for Free

14-day free trial. Cancel anytime.
Get Started
Join 20,000+ learners worldwide.
The first 14 days are on us
96% of learners report x2 faster learning
Free hands-on onboarding & support
Cancel Anytime