3. • Benjamin Franklin
• Proved that lightning was electricity by
flying a kite in a lightning storm
• Helped people understand the principles
of electricity
• Thomas Edison
–Invented the electrical light bulb
4. What is electricity?
• Electricity is a form of energy
• It is caused by a flow of tiny particles
called electrons through a material
5. Electricity
Electricity is a flow of electric charges
along a wire.
•This flow of electric charge is called a current
•Current is measured in the units of Amps (A)
6. What is an Electrical Circuit?
• A circuit is an electrical device that provides a
path for electricity to flow.
8. Resistor
• A resistor can change the amount of
current in a circuit
• In a variable resistor, the resistance can be
changed.
9.
10. Types of circuit
There are two types of electrical circuits;
SERIES CIRCUITS PARALLEL CIRCUITS
11. • The components are connected end-to-end, one
after the other
• They make a simple loop for the current to flow
round.
•Voltage is shared between the components
SERIES CIRCUITS
1.5V 1.5V
3V
12. PARALLEL CIRCUITS
•The components are connected side by side.
•The current has a choice of routes (paths).
•voltage is the same in all parts of the circuit
3V
3V
3V
14. DEFINITION OF 1 OHM
The resistance of a conductor is said to be 1 Ohm, if
current of 1 ampere flows through it when a
potential difference of 1volt is applied its ends.
16. UNIT OF CONVERSION
Prefix Symbol Multiplier Power of Ten
Terra T 1,000,000,000,000 1012
Giga G 1,000,000,000 109
Mega M 1,000,000 106
kilo k 1,000 103
none none 1 100
centi c 1/100 10-2
milli m 1/1,000 10-3
micro µ 1/1,000,000 10-6
nano n 1/1,000,000,000 10-9
pico p 1/1,000,000,000,000 10-12
18. LINEAR RESISTOR
•Resistors, which values
change with the applied
voltage and temperature, are
called linear resistors.
•They are subdivided as
FIXED and VARIABLE
Resistor.
19. OHM’S LAW
•Ohm established in the late
1820’s
•Ohm's law states that the
current through a conductor
between two points is directly
proportional to the voltage
across the two points.V = I*R
I = V/R
R = V/I
20. NON-LINEAR RESISTOR
•Nonlinear resistors are those
resistors, where the current
flowing through it does not
change according to Ohm’s Law
but, changes with change in
temperature or applied voltage
21. Thermister
•It is a variable resistor which
notices the change in
temperature.
•Its Resistance is inversely
proportional to the
temperature
•Thermisteres has a negative
temperature coefficient
(NTC) but there is also a
PTC (Positive Temperature
Coefficient)
22. Voltage Dependent Resistors
•The resistance of a VDR is
variable and depends on the
voltage applied
•Their resistance decreases
when the voltage increases.
23. Light Dependent Resistors
Resistor which terminal value
of resistance changes with
light intensity, When light falls
on the photoconductive cells
(LDR or Photo resistor), then
there is an increase in the free
carriers (electron hole pairs)
due to light energy, which
reduce the resistance of
semiconductor material.