Current, Voltage, and Resistance.ppt

science 8

1. CURRENT, VOLTAGE,
AND RESISTANCE
PREPARED BY : TYPE YOUR NAME HERE

2. •Infer the relationship
between current and
voltage

3. CURRENT
•Current:flow of electrical charges (electrons)
within a conductor or how fast charge is
moving.
•The symbol Iindicates the electric current,
and qshows that the electric current is
directly proportional to the amount of charges
that pass through a conductor for every unit of
time, t.

4. CURRENT
•The unit for current is coulomb per
Second (C/s) or Ampere (A)
•I = q/t

5. ANDRÉ AMPÈRE (1775 –1836)
•French physicist and
mathematician.
•One of the main
discoverers of
electromagnetism.
•SI unit of measurement of
electric current, the
ampere, is named after
him.

6. PROBLEM SOLVING :
1.Compute the current produced by a
6.5
x10-18C charge flowing in 15s.
Answer: 4.33 x10
-19
A
2. A steady current of 0.6 A flows
through a wire. How much charge
passes through the wire in 1 minute?
Answer: 36 C

7. ELECTROMOTIVE FORCE (EMF)
•It is a not a force. Instead it is a
potential energy given to unit to make it
flow through a conductor or around a
complete circuit. It acts like a charge
pump that cause charges to flow
through a circuit. As measurable
quantity, EMF is measured using the
unit volt (V).

8. •Electromotive force is what the
voltage source provides to a
circuit.It is the push given to
the electric charges for them
to flow from the source.

9. VOLTAGE/EMF
•Voltage:the charge (electron) “pusher.”
Voltage causescurrent to flow/move.
•Voltage sources:
•Battery
•Generator
•Outlets
•Symbol for voltage= V
•Unitfor voltage= Volts (V)

10. ALESSANDRO VOLTA (1745 –
1827)
•Italian physicist
•known especially for the
invention of the
electrochemical cell,
aka the battery in 1800.

11. VOLTAGE AT HOME
•Power utilities use large generators to
provide the 120V that is delivered to your
home outlets.
•When you plug in something to the outlet
(lamp, blow dryer, TV, etc) the voltage is
applied across the circuit, allowing the
charge to flow (electric current).

12. CURRENT
•The unit for current is coulomb per
Second (C/s) or Ampere (A)
•I = q/t

13. RESISTANCE
•Resistance:opposes the push from the
voltage source. Resistance affects the
speed of the current.
•Symbol for Resistance = R
•Unit for Resistance = Ohms (Ώ)

14. GEORG OHM (1789 –1854)
•German physicist
•Ohm determined that there is
a direct proportionality
between the voltage applied
across a conductor and the
electric current.
•This relationship is known as
Ohm's law.

15. VOLTAGE AND CURRENT
•If the voltage in a circuit increases, the
current will increase.
•If the voltage in a circuit decreases, the
current will decrease.
•This is a direct/proportionalrelationship.

16. RESISTANCE AND CURRENT
•If the resistance in a circuit increases,
the current will decrease.
•If the resistance in a circuit decreases,
the current will increase.
•This is an inversely proportional
relationship.

17. OHM’S LAW
•State the relationship between current,
voltage, and resistance.
•German physicist George Ohm had the
law named after him, because of his
extensive research.

18. V=IR
OHM’S LAW
Voltage is equal to the current multiplied by
the resistance.
Voltage,
measured in
Volts, V
Current, measured
in Amps, A
Resistance,
measured in
Ohms, Ω

19. OHM’S LAW EXAMPLES…
•If you want to find Voltage
in Volts:
V = IR
If I= 2 A and R = 5 Ohms
Then, V= (2A)(5Ω)= 10 V

20. EXAMPLES…
•If you want to find Resistancein
Ohm’s:
R = V / I
If V = 9 Volts and I = 4 A
Then R = 9 V/ 4A = 2.25 Ω

21. EXAMPLES…
•If you want to find Currentin
Amps:
I = V / R
If V= 140 V and R = 2Ω
Then, I = 140V/ 2Ω= 70 A

22. OTHER WORDS TO
REMEMBER:
•Electrical conductor –is any material
that allows the free flow of electric current.
•Electrical resistivity –is an intrinsic
property of the material that describes
how it resists the electric current flowing
through it

23. OTHER WORDS TO
REMEMBER:
•Electrical conductivity –the
counterpart of electrical resistivity.
•Electric circuit –is the pathway
for the current to move to and from
the source and the appliance.

24. OTHER WORDS TO
REMEMBER:
•Open circuits –where there is a gap
in a circuit and the current cannot flow.
•Closed circuit –it allow the current to
flow from the source of the current to
the load where the current is needed.

25. •Schematic diagrams –make it easy to
draw circuits.
•Basic Components of electric circuits
wire battery light bulb
Switch –open power pack
Switch –closedammeter
Resistor voltmeter
Single cellfuse

26. •Resistor –is an electronic component
used to provide a specific amount of
resistance. It can be considered as a load
•Types of Circuits:
•A. Series Circuit
B. Parallel Circuit:

27. Content, images, text, etc. used
belong to the rightful owner. No
copyright infringement intended.

28. •“However difficult life may
seem, there isalways
something you can
doand succeed at.”
―STEPHEN HAWKING