What is CURRENT– electric current explained, electricity basics

Summary

In this educational video from TheEngineeringMindset.com, Paul explains the concept of electrical current, covering its definition, the distinction between AC and DC, and the importance of current ratings for electrical devices. He discusses safety features like fuses and circuit breakers, which protect against electrocution and device damage, and demonstrates how to measure current using an ammeter or multimeter. The video is a comprehensive guide for anyone interested in understanding the fundamentals of electricity and electrical safety.

Takeaways

• 🔌 Current is the flow of electrons in a circuit and is essential for using electricity.
• 🧲 Copper is widely used for electrical wiring due to the ease of movement of its loosely bound electrons.
• 💡 Voltage, like pressure in a water pipe, pushes electrons to flow, making it necessary for electrical devices to function.
• 🔗 The capacity of cables and devices to handle electron flow is limited, similar to how pipes have a pressure limit.
• ⚡ The unit of measurement for current is the Ampere, often referred to as Amps, and is indicated on devices and components.
• 🔄 Alternating Current (AC) and Direct Current (DC) are two types of electricity with different electron flow patterns.
• 🏡 AC is used for long-distance power transmission due to its efficiency and the ease of voltage transformation using transformers.
• 📱 Small electronic devices like laptops and smartphones predominantly use DC for its controllability and compactness.
• 🔧 Measuring current in a circuit can be done using an ammeter or a multimeter, which is crucial for circuit safety and efficiency.
• 🛠 Fuses and circuit breakers are safety devices that protect electrical systems from damage caused by excessive current flow.
• ⚙️ Resistors can be used to control current flow and protect components from burning out by acting as 'speed bumps' for electrons.

Q & A

What is the definition of electrical current?

Electrical current is the flow of electrons in a circuit, typically in the same direction, which is necessary to use electricity.

Why are copper cables commonly used to form circuits?

Copper cables are used because the atoms in copper have a loosely bound electron in their valence shell, which is free to move easily and thus facilitates the flow of current.

What is the role of voltage in a circuit?

Voltage acts as the pushing force that drives the flow of electrons in a circuit, similar to pressure in a water pipe.

How is the flow of electrons measured in a circuit?

The flow of electrons, or current, is measured in Amperes, commonly referred to as Amps.

What does the rating on a fuse indicate?

The rating on a fuse, such as '3A', indicates the maximum current that the fuse can safely handle without blowing.

How does a device's label inform about its electrical requirements?

A device's label provides information about the voltage and current it requires to operate, such as 'input of 100-240 volts and 1.5 amps of AC'.

What is the difference between AC and DC electricity?

AC (Alternating Current) involves electrons moving back and forth, while DC (Direct Current) has electrons flowing in a single direction.

Why is AC used for long-distance power transmission?

AC is used for long-distance transmission because it can be transmitted efficiently and over greater distances than DC, and its voltage can be easily increased or decreased with transformers.

How can AC be converted to DC in electronic devices?

AC can be converted to DC using an inverter, which is common in electronic devices like laptops and mobile phones.

What is the purpose of an ammeter in measuring electrical current?

An ammeter is used to measure the flow of current in a circuit, providing a reading in Amps to indicate the rate of electron flow.

How does a resistor function in an electrical circuit?

A resistor acts to restrict the flow of current in a circuit, similar to a speed bump slowing down traffic, thus protecting components from excessive current.

What is the function of a fuse in an electrical circuit?

A fuse acts as a safety device that melts and breaks the circuit if the current exceeds a certain level, preventing damage to other components.

How does a circuit breaker protect an electrical circuit?

A circuit breaker automatically opens the circuit if it detects too much current, which can be caused by an overload or a fault, thus protecting the circuit and its components.

What is the significance of the number of electrons in the definition of an amp?

One amp is equal to the flow of one coulomb of charge per second, which is approximately six quintillion 242 quadrillion electrons.

How can a multimeter be used to measure current in a circuit?

A multimeter can be connected in series with the circuit to measure the current flowing through it, providing a reading in Amps.

What is the effect of connecting lamps in series on the total current in the circuit?

Connecting lamps in series adds resistance to the circuit, which reduces the total current flow, as electrons are slowed down by the increased resistance.

How does the resistance of lamps affect the current distribution in a parallel circuit?

In a parallel circuit, if lamps have different resistances, the current is distributed unequally, with more current flowing through the lamp with lower resistance.

Outlines

00:00

🔌 Understanding Electrical Current

In this segment, Paul from TheEngineeringMindset.com introduces the concept of electrical current, explaining it as the flow of electrons in a circuit facilitated by copper cables due to the loosely bound electrons in copper's valance shell. He discusses the necessity of a directional flow of electrons to produce useful work, such as lighting a lamp, which requires the application of voltage. Paul also covers the importance of current ratings on electrical devices and safety features like fuses to prevent electrocution and device damage due to excessive current flow. The distinction between AC (alternating current) and DC (direct current) is highlighted, with AC being the standard for power transmission due to its efficiency over long distances and the ease of voltage transformation, while DC is predominantly used in electronic devices for its controllability and compactness.

05:01

🔋 Measuring and Controlling Current

This paragraph delves into the quantification of electrical current, defining an amp as a measure equivalent to the flow of one coulomb of electrons, which is a staggering number of electrons per second. Paul illustrates how the current affects the brightness of a lamp and the necessity of measuring current using an ammeter or multimeter. He explains the concept of series and parallel circuits, demonstrating how resistance and the arrangement of components affect the flow of electrons. The use of resistors to control current and protect electrical devices is discussed, along with practical examples of using energy meters to measure appliance usage at home. Additionally, the importance of fuses as a safety device to prevent damage from excessive current is highlighted, emphasizing their role as a sacrificial element that breaks the circuit when overloaded.

10:02

⚠️ Circuit Protection and Safety Devices

In the final paragraph, Paul discusses the importance of circuit protection, focusing on fuses and circuit breakers as essential safety components. He explains how fuses contain a thin wire that melts when the current exceeds a safe level, thereby interrupting the circuit and preventing damage to more valuable components. Circuit breakers are described as automatic switches that trip in response to excessive current or heat, protecting the circuit from overload. The paragraph also touches on the life-saving aspect of circuit breakers, which can detect a sudden surge in current, such as that caused by an electrical shock, and cut the power almost instantly. Paul concludes by inviting viewers to continue learning about electrical topics and encourages questions and engagement in the comments section.

Keywords

💡Electrical Current

Electrical current is the flow of electrons in a circuit, which is fundamental to the operation of electrical devices. Defined as the rate of charge flow past a particular point in a circuit, it is central to the video's theme as it explains how the flow of electrons is utilized to generate heat, light, and power devices. In the script, Paul discusses how current is created by applying voltage and how it can be measured in Amperes (Amps).

💡Copper Cables

Copper cables are used to form electrical circuits due to copper's excellent electrical conductivity. The atoms in copper have a loosely bound electron in their outermost shell, which is free to move and conduct electricity. The script mentions copper cables as the medium through which electrons flow, making them a key component in electrical circuits.

💡Voltage

Voltage is described as the pushing force that drives the flow of electrons in a circuit, akin to pressure in a water pipe. It is measured in volts and is essential for creating current. In the video, Paul explains that more voltage results in more electron flow, which is crucial for understanding how electrical devices operate and are powered.

💡Ampere (Amps)

The Ampere, or Amp, is the unit of measurement for electrical current. It signifies the amount of electric charge passing a point in a circuit per second. The script uses the example of a fuse rated for three amps to illustrate how current is limited in electrical systems to prevent damage.

💡Alternating Current (AC)

Alternating Current, or AC, is a type of electrical current where the electrons flow back and forth periodically. The script explains that AC is used in homes and for long-distance power transmission due to its efficiency and the ease with which its voltage can be transformed.

💡Direct Current (DC)

Direct Current, or DC, is a type of electrical current where electrons flow in a single direction continuously. The video mentions that devices like laptops and mobile phones use DC, as it is easier to control and allows for more compact circuit designs.

💡Transformers

Transformers are devices that can increase or decrease the voltage of an AC supply. They are essential for适配ting the high voltage used in power transmission to safer levels suitable for home and industrial use. The script refers to transformers in the context of AC's advantages over DC for long-distance transmission.

💡Inverters

Inverters are used to convert AC to DC. They are common in electronic devices where DC is required for operation. The video script mentions inverters as a means to explain how AC from the power grid can be converted to DC for use in devices like laptops.

💡Ammeter

An ammeter is a device used to measure the flow of current in a circuit. It is connected in series with the circuit, allowing the current to flow through it. The script describes using an ammeter, or more commonly a multimeter set to measure current, to determine the rate of electron flow.

💡Resistors

Resistors are components in a circuit that oppose the flow of current, thereby reducing its amount. They are used to control the current and protect other components from excessive current flow. The video script provides an example of using a 270 Ohm resistor to prevent an LED from burning out when connected to a higher voltage battery.

💡Fuses

Fuses are safety devices that protect electrical circuits from overcurrent conditions. They contain a thin wire that melts when too much current flows through it, breaking the circuit and preventing damage. The script explains how fuses act as a weak point in the circuit, designed to fail safely and protect more expensive components.

💡Circuit Breakers

Circuit breakers are automatic switches that open to break the circuit when too much current flows, or when a surge is detected, such as from an electrical shock. They are designed to protect both the electrical system and users from potential harm. The video script describes how circuit breakers operate to prevent damage and provide safety.

Highlights

Electrical current is the flow of electrons in a circuit, essential for using electricity.

Copper is popular in circuits due to its loosely bound electrons that move easily.

Electrons need to flow in the same direction for useful work, like lighting lamps.

Voltage is the force that pushes electrons to move, akin to water pressure in pipes.

Cables and electrical devices have ratings to prevent damage from excessive current flow.

Current is measured in Amperes (Amps), with a fuse rated for a specific current.

Device labels indicate the input voltage and current they require, like a laptop charger.

Alternating Current (AC) and Direct Current (DC) differ in electron flow direction.

AC is used for efficient long-distance power transmission and can be easily transformed.

DC is easier to control and is used in small electronic devices like laptops and phones.

Appliances may use both AC and DC, with different components requiring different types.

An ammeter measures the flow of current in amps, similar to a water meter.

One amp is equivalent to the flow of approximately six quintillion electrons per second.

A multimeter can be used to measure current in series with a circuit.

In a series circuit, adding resistance reduces the overall current flow.

In a parallel circuit, the total current is the sum of the currents in each branch.

Resistors can be used to limit current and protect devices from burning out.

Energy meters can measure and calculate the cost of using electrical appliances.

Fuses act as a weak point to protect circuits by breaking if too much current flows.

Circuit breakers automatically open to prevent damage from excessive current or a surge.

Transcripts

Hey there, guys,

Paul here from TheEngineeringMindset.com.

In this video,

we're going to be discussing electrical current.

We'll be looking at what is current,

the different types of current,

how to check the ratings of your electrical devices.

As well as how we use safety features

to save you from being electrocuted.

Current is the flow of electrons in a circuit.

To use electricity,

we need electrons to flow

in the same direction around a circuit.

We usually use copper cables to form the circuit

because the atoms that make copper

have a loosely bound electron in their outermost,

or valance shell,

which is free to move around inside the metal.

This free electron is very easy to move,

which is why copper is so popular.

It's so easy to move

that it will naturally just move

to other copper atoms by itself,

but this occurs randomly in any

and all directions which isn't useful for us.

For us to make use of this,

we need lots of electrons to flow

in the same direction along the circuit.

We can then place things like lamps

in the way of these electrons so that they flow through it

and then they generate light and heat, etc.

To do this, we need to force the electrons to move

and we can do that by applying a voltage.

Voltage is the pushing force.

It's like pressure in a water pipe.

The more pressure we have,

the more water can flow,

the more voltage we have,

the more electrons can flow.

We covered the basics of voltage

in detail in a previous video.

Do check that out,

link's in the video description down below.

So we need a lot of electrons to flow along a circuit

and through our lamps to get them to shine brightly.

However, the cable and lamps can only handle

a certain amount of electrons passing through them.

Just like a pipe is rated to handle a certain amount

of water passing through it or a certain pressure.

If it exceeds this,

then the pipe will burst.

Likewise, if too many electrons

pass through the cable or the lamp,

then they will just burst or burn out.

We refer to the flow of electrons as current,

and we measure this in the unit of Amperes,

although you'll usually just hear people say Amps.

This is represented with a capital A.

For example, this fuse has a three and a capital A,

which means it's rated for three amps of current.

We'll look at how we use fuses later on in this video.

If you look on the plugs of your electrical devices,

you should find labels from the manufacturers,

which tell you what the product is designed to handle.

For example, this laptop charger

tells us that for the device to work,

it needs an input of between 100 and 240 volts

and 1.5 amps of AC, or alternating current.

The charger will then convert this

to give an output of 19.5 volts

and 3.3 amps of DC, or direct current.

AC and DC are different types of electricity.

The plugs in your homes will provide AC,

or alternating current.

In this type,

the electrons do not flow in a continuous loop.

They instead alternate between

moving backwards and forwards,

just like the tide of the sea.

Your electrical devices,

like laptops and mobile phones,

will use DC electricity, or direct current.

In this type, the electrons do flow in only one direction,

much like the flow of water in a river.

We transport electricity from

the power stations in AC, alternating current,

and send this to our cities and homes.

We use AC here because it can

be transported very efficiently

and over much greater distances

than if we were to use DC, direct current.

We can also very easily increase

or decrease the voltage using simple transformers.

We've covered how transformers work in our previous videos.

Links down below for that,

do check them out.

We mostly use DC, direct current,

in the circuit boards of small electronic devices,

like laptops, mobile phones and televisions.

That's because DC is easier to control

and allows circuits to be smaller and more compact.

Many appliances will use a combination of AC and DC.

For example, a washing machine

will use AC for the induction motor,

which is used to spin the tub with the clothes in,

but the circuit board which controls the settings,

the lights, the timers,

as well as how fast the motor spins,

will use DC power.

We can convert AC to DC using an invertor.

This is extremely common in electronics.

We covered how inverters work previously.

Links down below if you want to watch

and learn about that also.

People often refer to a river

or the tide of a sea as having a strong current.

It's very similar to electricity.

A river with a lot of fast flowing water

is said to have a strong current.

The same with electricity.

A cable with a lot of electrons

flowing through it has a high current.

A river is able to handle a certain

amount of water flowing through it,

but if more water enters

than the river can handle,

then the river will burst its banks.

The same with electricity.

A cable will burst and burn out.

Therefore, manufacturers need to be able to test cables

and lamps to find out how much current they can handle.

We also want to be able to see how much current

is flowing through our circuits

as well as being able to calculate this.

We can measure this using an ammeter

where we measure the flow of current

in the circuit using the units of amps.

So what is an amp?

One amp is equal to one coulomb,

and one coulomb is equal to approximately

six quintillion, 242 quadrillion electrons per second.

What does that mean?

Another way to look at this is that

to power this 1.5W lamp with a 1.5V battery,

approximately, six quintillion, 242 quadrillion

electrons need to flow from the battery

and through the lamp

every second for the lamp to stay on.

If we reduced the voltage,

then less electrons will move

and the lamp will become dimmer.

If we increase the voltage,

then more electrons will flow

and eventually the lamp will not be able to cope

so it will burst or burn out.

So to measure the current in a circuit,

we need to connect an ammeter in series

so that the current flows through it.

Think of it like a water meter.

The water need to flow through the water meter

for us to know how much water is flowing in the pipe.

Likewise, we need the electrons to flow through our ammeter

so that we know how much electricity

is flowing in our circuit.

Instead of using an ammeter,

we're going to use a multimeter

as we can do a lot more with this device.

I'll leave some links down in the video description

where you can pick up a good multimeter cheaply.

I highly encourage you to get one of these for your toolkit.

They're pretty cheap and are very useful.

If we connect a lamp to a battery in series,

then we can measure the current using

a multimeter by connecting it in series.

If we connect this 1.5 volt battery

and this lamp,

which has a resistance of one Ohm,

then we get a current of 1.5 amps,

which means nine quintillion, 636 quadrillion electrons

are flowing through the lamp every second.

Because it's in series,

all the electrons in the circuit

are flowing along the same path.

So that means we can move the multimeter to here

and we get the same reading.

If we add another lamp to the circuit connected,

again, in series,

the lamp also has a resistance of one Ohm,

then we are adding more resistance to the circuit,

so the electrons are slowed down.

In this case, we get a reading of 0.75 amps,

which means four quintillion, 818 quadrillion electrons

are flowing per second.

This is in series,

so again we can move the multimeter

and we get the same reading.

If we now connect the circuit with two lamps in parallel,

both with a resistance of one Ohm

and connect this to a battery of 1.5 volts,

then in the main wire,

to and from the battery,

we get three amps.

But on the branch of each lamp,

we get 1.5 amps.

That's because the path for the electrons has split,

so the electrons are shared

with some flowing through lamp A

and some flowing through lamp B.

In this example,

both lamps have an equal resistance

so the current is split equally.

But if the lamps are of different resistance,

then the current is split unequally.

For example, if lamp A has a resistance of one Ohm

and lamp B has a resistance of three Ohms,

then in the main wire,

we get an amp reading of two amps.

In the branch for Lamp A,

we get 1.5 amps,

and in the branch for lamp B we get 0.5 amps.

As you can see,

lamp B is dimmer because there is a higher resistance

so less electrons can flow through it.

In both cases,

the amps in the branches will add up

and are equal to the total current flowing

in the main wire to and from the battery.

Now, I mentioned that lamp B was dimmer

because the resistance was higher.

If you remember,

I also said that cables and lamps, etc.,

are only rated to handle a certain amount of current.

If it exceeds this,

then they can burn out.

So restrict the amount of current that can flow,

we can add resistors into the circuit

or into part of the circuit.

These act like speed bumps and slow the electrons down.

Resistors are like putting a bend into a garden hose.

The kink adds resistance to the flow of water,

which reduces the amount of water

that can flow out of the hose.

Similarly, we can add resistors to the circuit

and it slows down the electrons.

For example, this LED is rated at 25 mA and 3.3 volts.

But our battery is rated at nine volts.

So if we were to connect the LED to the battery,

it would just burn out because it can't

handle that much voltage and current.

So to stop the battery from burning out,

we need to place a resistor into the circuit.

In this case, we'll use a 270 Ohm

resistor to bring the voltage

and current down to a safe level for the LED.

If you want to see how much current

is flowing through your electrical devices at home,

then you can use one of these cheap energy meters.

You simply plug your appliances into it,

and it'll measure the voltage,

amps, watts, power factor, etc.,

and you can then even calculate

how much it costs to use the appliance.

I recommend you have one of these.

They're a great little device for your toolkit.

I'll leave some links down below

for where you can get a good one very cheaply.

So we saw earlier that we can use resistors

to reduce the amount of current flowing in the circuit

and protect our devices.

Another thing we can use is a fuse.

Fuses in a basic sense,

have a thin piece of wire inside them,

which is rated to handle a certain

amount of current flowing through them.

In this case, this one is rated to handle three amp,

or 19 quintillion, 272 quadrillion electrons per second.

The fuse acts as a weak point

and it's very cheap to replace.

So if too much current flows in the circuit,

it will burn out and open to break the circuit

and protect the more expensive electrical components.

You can find these melted on circuit boards

and you can also find these built into some plugs.

For example, this plug from the UK has a fuse

built into it to protect the electrical device.

Another device we use,

and you've probably seen these in your homes,

this is the circuit breaker.

It's essentially a switch that will automatically

open to break the circuit if it detects too much current

or too many electrons flowing through it.

It's rated to handle a certain amount

of electrons flowing through it per second,

but it measures this using heat

or an electromagnetic field to detect

and act on if too many electrons are passing through it.

If it exceeds this,

then it will open to break the circuit.

If for example, we slowly add load to a circuit,

then the bimetallic plate will detect

this slow rising current because

the current causes it to heat up.

As it approaches the designed rating,

it will break the circuit to cut the power

and protect the cables and devices.

The load can then be reduced

and the circuit breaker reset,

unlike a fuse.

Another extremely important function is if for example,

you touch a live component

and receive an electrical shock.

There will be a sudden surge in current

and the circuit breaker can detect this

and cut the power almost instantly

to stop you being electrocuted

and save your life.

Okay, that's it for this video,

but if you want to continue learning about electricity

and electrical engineering,

then just click one of these videos on the screen now

and I'll catch you there for the next lesson.

If you have any questions,

let me know in the comment section down below.