# Watts, Amps and Volts and How To Understand Electricity

## So What Are Watts, Amps and Volts All About?

A guide to the basics of **electricity**. Here is everything you need to know about electrical power (Watts), current (Amps) and voltage (Volts), how to understand simple electricity and the way these parameters relate to one another.

**Lets begin with some simple definitions:**

**Amps**

Electricity consists of the flow of **electrons** through a conductor such as an electric wire. You can’t see electrons but a helpful analogy is to think of electricity as the flow of water through a pipe.

We measure the rate of flow of electricity as an **electric current** (just as we think of the rate of flow of water in a river as the river current). The letter used to represent current in an equation is** I**.

Electric current is measured in **Amperes**, shortened to **Amps** or simply the letter **A**.

**A current of 2 Amps can be written as 2A**. The bigger the current the more electricity is flowing.

## Volts

So what makes the current flow in the first place? A device such as a battery provides what is known as a potential difference in an electric circuit.

If we go back to our water analogy, the battery is like a water pump that propels water through a pipe.

It creates pressure in the pipe causing the water to flow. So how do we measure this pressure? We call electrical pressure **Voltage** and measure it in **Volts**, shortened to **V**. The letter **V** is also used represent Voltage in an equation.

**A voltage of 3 volts can be written as 3V.**

The bigger the voltage the higher the pressure and the more current flows. But in order for the current to flow, the electrical conductor or wire must loop back to the battery.

If we break the circuit, with a switch for example, then no current will flow.

## Electric Current

## Resistance

Before we get onto Power and Watts we need to understand **Resistance**. The letter **R** is used to represent resistance in an equation.

In the case of our battery, if we short circuited it with the wire (no bulb), the wire and battery would get very hot and the battery would soon be flat.

That is because there would be virtually no resistance in the circuit so a huge electrical current would flow until the battery was empty.

But once we add our bulb to the circuit, the bulb offers a lot of resistance and creates a local 'blockage' (or narrowing of the pipe) where the current finds it hard to flow.

This greatly reduces the current flowing in the circuit which means the energy in the battery is released more slowly.

As the battery forces the current through the bulb the battery's energy is released in the bulb in the form of light (and heat).

In other words, the current carries stored energy from the battery to the bulb where it is turned into light and heat energy.

**Resistance** is measured in **Ohms** or **Ω** (Omega) for short.

**So 5 Ohms can be written 5Ω.**

## Watts

So how do Current and Voltage relate to one another? Well, the bigger the current the brighter the light and similarly the bigger the voltage the brighter the light.

Both the voltage and the current in the bulb determine how much energy is released in a certain time.

The **Watt** is a measure of **power **or how much energy is released per second. It can be shortened to **W**.

**1 Watt can be written 1W**.

We can calculate the power released in a bulb by multiplying the voltage in Volts across the bulb by the current in Amps flowing through the bulb **(W = V x I)**.

**For example a current of 2 Amps flowing through a bulb with 12 Volts across it generates 24 watts of power. **

**In the UK**, domestic power is supplied at 240 Volts. A 100 Watt bulb will therefore draw a current of 100/240 Amps (about 0.4A). This means a 1A fuse can be safely added to the mains plug of a desk lamp with a 100W bulb because 1A is much greater than 0.4A.

**In the USA**, the domestic supply is typically 110V, safer than the UK, and this means a 100W bulb draws a current of 100/110 Amps (about 0.9A).

## Simple Calculations

These simple calculations are summarised in the formulae in the circle to the right. So, for example, we can calculate the power in Watts (see orange area top left of the circle) as **V x I**.

Hopefully now you now understand the difference between** electric current, measured in Amps, voltage, measured in Volts or electrical power measured in Watts. **

Finally, remember that if you know the voltage of your power supply then you can calculate the current through a bulb, fuse or other electrical appliance or component, based on its rating in Watts.

## Electricity Quiz - A couple of questions to try

## Electricity Video

## 35 comments

Lovely. Wonderful explanation of Watts, Amps, and Current.

Even though your blog is an excellent "guide to the basics of electricity", there are a couple of things that need to be considered:

You said, "In the USA, the domestic supply is typically 110V, much safer than the UK."

This is not true.

Firstly, the voltage in the UK is officially 230v (single phase, domestic).

Secondly, the voltage in the USA is 120v (domestic).

120v is in no way "safer" than 230v. A "safe" voltage is considered to be less than 50v RMS (AC) or 120v DC (ripple free). These voltages are known as "extra low voltages" & relate to "touch voltage limits".

You also said: "Finally, remember that if you know the voltage of your power supply then you can calculate the current through a bulb, fuse or other electrical appliance or component, based on its rating in Watts."

I think that you meant to say, "Finally, remember that if you know the voltage of your power supply then you can APPROXIMATELY calculate the current through a bulb, fuse or other electrical appliance or component, based on its rating in Watts."

Yeah, you really can't get the calculation it to an exact. But you can definitely get an approximate.

Thanks for this mate.

Helped a lot with my schoolwork. :P

Everyones a cridic. I understood completely and I understood that it is not on the money, and those of us who don't have to act like know it all's realize that there are factors involved that makes the math close, but there is room for error. Maybe thicknees of the wire being used, battery losing power, or whatever the reason. People chill!!! If I understood and realise this then you brain childeren should. Anal Bastards.

Useful and well-presented article! A lot of people seem to get confused about Watts and Amps and Volts - an explanation like this has been long overdue.

thanks for the free lesson. you made it very clear and easy to understand. here is a smart formula i'd like to pass on to beginners like myself. U+P=R or utilization plus practice equals retention. i wish there had been internet and google when i was a kid. best regards teach. bk

Shouldn't your graphic read I = sqrt(P) / R instead of I = sqrt(P) / V?

First, thank you does not say enough for this. I am a slow learner and forward to using this to help learn about electricity. I am finding out that it is not that hard, but like Bert K commented, U+P=R. Thank you again so much Mr. Ravado

Clear as crystal

I have a question.. Can the magnetic energy be converted to electric enegergy somehow by properly placing them on a flywheel? Rotating the flywheel using the magnetic force. There are lot of things going on the web about it. And how come they only sell guides but not the finished product.

Thanks for the heads-up Rik. I want to implement cheap renewable energy, could you outline few options? Pv or solar panels are not the options where i live. I heard a lot about fuel cells, are they expensive?

how do we determine the maximum limit of ampereage that can be drawn out of a 120 volts line

thanks for the answer. sir please give one more answer about transformers. I read somewhere that transformers can increase and decrease the voltage of a said line, so in that case is it possible to decrease the incomming 220v main line of my house to say 24v and then again increase it 220v for normal usage. will the performance be the same and will it decrease the electric bill.

Good explanation with examples

Very useful explanation.

I had cleared many doubts by using this........

I found it interesting that elkangorito said no way 120 is safer than 230 volts. Then why in England on ALL commercial work sites the max voltage used is 120? Everything is stepped down from 230 to 120.

Thanks

Can someone help to find out 12 volt ??? w required in the given satiation?

I required 220 volt 1000 w to run my application. i am planning to install solar panel to have full fill my requirement. it involve solar panel ,12 volt battery, and power inverter, how many watts of 12 volt panel do i required to have 220 volt 1000w power to run my application

great blog

Illustrated beautifully with a photo of Naomi Watts (wtf?) - clearly all this electrical stuff is about tits. Nice touch.

Thanks for the tutorial...it has been awhile and was looking for the basic equations. According to your article, "A" is short for amperes or amps. Later, "I" is introduced without relating it to amps. For clarity, you might add that.

Thanks a lot for your wonderful detail explainatin. I hope it would be very helpful to all beginers. Best wishes for your blog.

That was useful thanks

Please advise this old lady if I can use Gu10 replacement bulbs with 110/220 in the uk, as I bought them in error, thanking you in anticipation,

Marj

Very good

Being engineer myself I enjoyed reading the concepts.

hi there, i am just getting to know about electricity. and has always been confused to hell, what is Amps, Volts etc. now i understood it all.

thanks for the article. God Bless

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