Unless, you’ve been living under the rock for the 2 centuries, you definitely can relate to whirr of an electric motor.  Wherever you look around, if you are able to detect a soft buzz or a growling hum or a shrieking ping, you’ve probably homed in on the presence of an electric motor in your vicinity.

This ubiquitous little invention, as  it would have been referred to back when it was invented, is a technological marvel that changed the course of Human Civilization and propelled us towards the path of the information age. Ever since conceptualization by the eminent British physicist Michael Faraday, Electric Motors have been a major part of our lives. 

Look around and you can spot a few around you! There are probably two in your computer for starters, one spinning your hard drive and the other one powering the cooling fan. If you're sitting in a bedroom, you'll find motors in hair dryers and many toys; in the bathroom, they're in your ventilation fans and electric shavers; in the kitchen, motors are in just about every appliance from washing machines and dishwashers to microwave oven.

So, how much do us all know about this invention which is an integral part  of our lives. Well, it’s always to good time to learn. So, let’s learn things now.

Electromagnetism

This is the main phenomenon behind the working of all electrical appliances. Discovered by Hans Christian Oersted, this phenomenon is what makes a motor run. You wanna see how it works? Simple. Take a length of an ordinary wire, make it into a big loop, and lay it between the opposite poles of two powerful magnets. Now, if you connect the two ends of the wire to a battery, the wire will jump up briefly. Why does this happen? Because of electromagnetism! If you place the wire near a permanent magnet, the temporary magnetic field caused by the flowing current interacts with the permanent magnet's field. 

Science behind Electric motors.

You can consider electric motors as just two friends who are pulling the carousel around. 

The basic idea of an electric motor is really simple: you let some current into into it at one end and a  metal rod rotates at the other end enabling you to harness the motion to drive a machine of some kind. How does this work in practice? Exactly how do you convert electricity into movement? 

Well, for that, we need know about this guy

More particularly about his hands, to understand how motors work.

Fleming’s Left Hand Rule 

Originated by John Ambrose Fleming in the late 19th century, the Fleming’s Left Hand Rule is an easy way of working out the direction of motion by in an electric motor. 

When current flows in a wire, and an external magnetic field is applied across that flow, the wire experiences a force perpendicular both to that field and to the direction of the current flow.

A left hand can be held, as shown in the illustration, so as to represent three axes- x, y, z on the thumb, first finger and middle finger. Each finger is then assigned to a quantity (mechanical force, magnetic field and electric current). 

One can figure out the direction in which the wire will move using Fleming's Left-Hand Rule. 

How to do this?

The Thumb, Index finger and Middle finger of your left hand must be stretched in such a way that all three are at right angles. Point the Middle finger in the direction of the Current (which flows from the positive to the negative terminal of the battery), and the Index finger in the direction of the Field (which flows from the North to the South pole of the magnet), your thumb will show the direction in which the wire Moves. 

• Index finger = Field
• Middle finger = Current
• Thumb = Motion

Now, how does this make a motor rotate?

Suppose we bend our wire into a squarish, U-shaped loop so there are effectively two parallel wires running through the magnetic field. One of them takes the electric current away from us through the wire and the other one brings the current back again. Because the current flows in opposite directions in the wires, Fleming's Left-Hand Rule tells us the two wires will move in opposite directions. In other words, when we switch on the electricity, one of the wires will move upward and the other will move downward.

If the coil of wire could carry on moving like this, it would rotate continuously—and we have our electric motor. 

This simple yet marvellous science is what powers the modern age- from small DC motors on our toys to the giant ships that traverse the earth !