10 G8 Science Q1- Week 5-6-Current Vs Voltage-.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 I indicates the electric current, and q
shows 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
x10-18 C 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
causes current to flow/move.
•Voltage sources:
•Battery
•Generator
•Outlets
•Symbol for voltage = V
•Unit for 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/proportional relationship.

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 Resistance in
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 Current in
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 –openpower 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
is always something
you can do and succeed
at.”
― STEPHEN HAWKING