Current and Resistance likely covers these key points: Electric Current – The flow of electric charge, measured in amperes (A). Voltage (V) – The potential difference that drives current through a circuit. Resistance (R) – The opposition to current flow, measured in ohms (Ω). Ohm’s Law – V = IR, where voltage equals current times resistance. Factors Affecting Resistance – Material, length, cross-sectional area, and temperature. Series and Parallel Circuits – How resistance behaves in different circuit configurations. Applications – Real-world examples like resistors in electronics and heating elements.

1. Current

2. 2
The glow in the
filament of an
incandescent
lightbulb is caused by
the electric current
passing through it.

3. 3
This electrical energy
is transformed into
thermal energy. This
causes the wire to
reach very high
temperatures, making
it glow.

4. 4
Every day, we observe the application of electric
current in several electrical devices.

5. 5
Electric current exists in conductors such as
wires, semiconductors, and even in human
cells.
In this lesson, we will learn about the motion of
charges and other factors affecting it.

6. 6
How do charges move in a
conductor?

7. 7
Electricity
What examples in real life do you use electricity?

8. 8
Electric Current
● Any movement of charges from one region to another
is called current.
● Specifically, the electric current is defined as the net
charge flowing through an area per unit time.

9. 9
Electric Current
Consider charges moving in a direction perpendicular to a
cross-sectional area of a wire.

10. 10
Electric Current
In this case, the direction of current is the same as the
flow of positive charges.

11. 11
Electric Current
In this case, the direction of current is opposite as the
flow of positive charges.

12. 12
Electric Current
In both cases, the average current is mathematically
defined as:
In a general sense, all currents are simply the averages of
the charge passing through an area over time.

13. 13
Electric Current
On the other hand, instantaneous current is the limit of
the average current as the time interval approaches zero.

14. 14
Electric Current
● Electric current has an SI unit of coulomb per second
(C/s) or the ampere (A).

15. 15
Electric Current
● Electric current has an SI unit of coulomb per second
(C/s) or the ampere (A).
● It was named after André-Marie Ampère, a French
physicist and mathematician, who laid the foundations
of electrodynamics, now known as electromagnetism.

16. 16
Electric Current
● Charges flowing through a surface can be positive,
negative, or both.

17. 17
Electric Current
● Charges flowing through a surface can be positive,
negative, or both.
● In metals, moving charges or charge carriers are
always negative.

18. 18
Electric Current
● Charges flowing through a surface can be positive,
negative, or both.
● In metals, moving charges or charge carriers are
always negative.
● In plasma, these charges may include both positively-
and negatively-charged ions.

19. 19
Electric Current
● The conventional current is defined based on the
direction of the flow of positive charges.

20. 20
Electric Current
● The conventional current is defined based on the
direction of the flow of positive charges.
● The opposite of the conventional current is electron
flow.

21. 21
Concept Formula Description
Electric Current
where
● Iav is the average current
in coulomb per second
(C/s or A);
● ΔQ is the amount of
charge in coulombs (C),
and
● Δt is the time interval in
Use this formula to
solve for the average
electric current if the
amount of charge and
the time interval are
given.

22. Resistance

23. 23
A diode is a device
that allows current to
flow in one direction
while restricting its
flow in the other
direction.

24. 24
To function as such, it
should have low
resistance in one
direction but has a
high resistance in the
other direction.
polarized ends

25. 25
Semiconductors, such as silicon, can be
effectively used in this specific application.

26. 26
What is resistance?

27. 27
Resistance
When you hear the word resistance, what comes in your
mind?

28. 28
Resistance
Is it something you fight for?

29. 29
Resistance
Or is it something that fights over all else?

30. 30
Resistance
● Resistance is the opposition of a material to the flow of
charges.

31. 31
Resistance
● Resistance is the opposition of a material to the flow of
charges.
● This flow is hindered by the collisions of atoms within
the conductor.

32. 32
Resistance
● Resistance is the opposition of a material to the flow of
charges.
● This flow is hindered by the collisions of atoms within
the conductor.
● Resistance is also defined as the proportionality factor
between the voltage and the current passing through
the wire, expressed as R = V/I.

33. 33
Resistance
The SI unit for resistance is the ohm, abbreviated as Ω,
which is the Greek capital letter omega.

34. 34
Resistance
● All electrical devices have a specific resistance to the
current.
○ load: electric heaters, filaments in light bulbs
○ wires

35. 35
Resistivity
● Resistivity is the measure of resistance of a specific
material for a given dimension.
● It is abbreviated as ⍴, which is the Greek letter rho.

36. 36
Resistivity
● The greater the resistivity of the material, the greater
the electric field needed to produce a given current
density.
● What do you think is the SI unit of resistivity?

37. 37
How is resistance related to
resistivity?

38. 38
Resistivity
● The resistance of a conductor is affected by the length,
the area, and the type of material. It can be expressed
as
● Every material has a specific value for resistivity,
depending on its atomic structure and temperature.

39. 39
Resistivity

40. 40
Concept Formula Description
Resistivity
where
● E is the magnitude of the
electric field in the material,
and
● J is the magnitude of the
current density caused by the
electric field.
Use this formula to
solve for resistivity if
the magnitude of the
electric field and the
magnitude of the
current density are
given.

41. 41
Concept Formula Description
Temperature
dependence
of resistance
where
● R is the resistance at a
temperature T;
● R0 is the resistance at a reference
temperature T0;
● α is the temperature coefficient
of resistivity;
● T is the temperature, and
Use this formula to
solve for resistance if
the reference
resistance, reference
temperature, final
temperature, and
temperature
coefficient of resistivity
are given.

42. Ohm’s Law

43. 43
Ohm’s law is
considered as one of
the foundations of
electronics. Its uses
span across both
domestic and
industrial
applications.

44. 44
It is so prevalent that
even our own nervous
system operates in
accordance with it.

45. 45
Our nerve cells store electrochemical potentials
that then become responsible for the production
of signals essential for the various functions.

46. 46
What does Ohm’s law state?

47. 47
What relations among current,
resistance, and voltage can we
deduce from the formula V = IR?

48. 48
Recall
Can you define current, voltage, and resistance?
What analogy can you think of these variables?
Can you identify real-life scenarios that involve these
variables?

49. 49
Recall
A conductive path that permits the continuous flow of
charge, called current, driven by the voltage and
opposed to some degree by resistance, forms an electric
circuit.

50. 50
Ohm’s Law
Ohm’s law states that the amount of current in a given
circuit is determined by the amount of voltage and
resistance present in the system.

51. 51
Ohm’s Law
Key Quantities in Ohm’s Law
Quantity Symbol
Unit of
Measurement
Definition
current I ampere (A) rate of the flow of
charges
voltage V (or E) volt (V) drives electron
flow
resistance R ohm ( ) controls and
restricts electron
flow

52. 52
Ohm’s Law
Ohm’s discovery revealed that “the amount of current
flowing through a conducting material in a circuit is
directly proportional to the potential difference across it”.

53. 53
Ohm’s Law Triangle

54. 54
What does the Ohm’s law state?

55. 55
Ohm’s Law Triangle

56. 56
The unit for charge, C, stands for
coulomb. Current is denoted by the
letter I, which stands for “intensity”, or
more specifically, current intensity.