This presentation gives a brief information about basics of electricity. It also provides activities to help you understand it.

1. Basic Electricity

2. Each and every matter in this world is
made up of atoms. Atom is the
smallest part of the matter. At the
center of the atom, there is nucleus
with protons (+ve charge) and
neutrons (neutral). It is orbited by
one or more electrons (-ve charge).
In some materials, electrons are tightly bound to the
atoms. On the other hand, some materials, especially
metals have electrons which can detach from the atom
easily. These are called free electrons which help
electricity to flow through this material. And that is why
these materials become electrical conductors while the
materials with electrons tightly bound to the atoms
become electrical insulators.

3. Examples of electrical insulators:
wood, cotton, glass, plastic etc.
Examples of electrical conductors: Most of the metals
are good conductors of electricity. Copper, Silver, Gold
to name a few.
An atom is called electrically neutral when the no. of
electrons are equal to the no. of protons present in it.

4. •It is the movement of free electrons
between different atoms which
creates electricity.
•The flow of electrons is called the
current.
•The unit of current is ‘amps’
For electricity to flow, there has to
be something to push the electrons
along.
This is called an electromotive
force (EMF). A battery or power
outlet creates this Electromotive
force which induces current in a
circuit.
EMF is measured in volts

5. Potential Difference:
The difference in EMF across two points is called the
potential difference. (change in electrical potential
energy).
What is the potential
difference of this light bulb?
3 volts 5 volts
5 volts - 3 volts = 2 volts
So, where did the 2 volts go?
- They have been transferred
from electrical energy into
light energy.
- +

6. Power
Power = work done
Work done = moving an electron from one place to another
Power is measured in Watts
Power (Watts) = EMF (Volts) x Current (amps)
Power = EMF x Current
- - -
- - -

7. Power Activity 1
EMF = 2 volts, Current = 11 amps
What is the power of this CFL bulb ?
EMF = 8 volts, Current = 11 amps
What is the power of this filament bulb?
Which one do you think is better to use and why?

8. Electrical energy means work done in a period of time.
Electrical energy is measured in Joules (in SI units).
Since a watt is just a joule per second (J/s), a kilowatt
hour is a measure of energy which is normally used
everywhere.
(1 kW hr = 1000 W hr = 1000 J/s hr = 1000 J/s * 3600
s = 3.6 * 106 J)
Kilowatt Hours (kwh) = power x time
= EMF x current x time
Funny Facts:
Electricity travels very fast (186,000 miles per second). If you traveled
that fast, you could travel around the world eight times in the time it
takes to turn on a light! And if you had a lamp on the moon wired to a
switch in your bedroom, it would take only 1.26 seconds after you flipped
the switch for electricity to light the lamp 238,857 miles away!

9. Activity 2
a. A hand grinder at Vigyan Ashram workshop has a power rating
of 800 watts. It runs for 20 minutes a session and is used 2
times a day. Calculate the daily electrical energy that is
needed in kwh.
Hint: Length of time in a day = 2 times x 20 minutes
= 40 minutes /day
Convert to hours = 40 mins /60 mins = 0.66 hour
b. The water pump at Vigyan Ashram uses 4.4 kwh a day. It
runs for two hours a day. If the EMF of the pump is 230 volts
what is the current used?