1) The document describes electrical circuits and their components, including batteries, resistors, switches, and how voltage, current, and resistance are related. 2) Key concepts covered include series and parallel circuits, and how voltage and current are distributed in each. Formulas for calculating total resistance, voltage, and current are also provided. 3) Examples problems are given to demonstrate calculating various circuit values for series, parallel and combination circuits.

2. Power source
To supply
electrical power
Conductor
To conduct
electricity
A device that
uses energy
A switch that controls the flow of
electricity is a good addition

3. Cell
Battery
Light Bulb
Resistor

4. Switch
Ammeter Voltmeter

5. 𝒆−
Electrons are
supplied at the
negative pole of
the battery
Flow from
negative to
positive
Electrical current is the flow of electrons

6. Historically it was
thought electricity
was the flow of +
charges
Flow from positive to negative
We still use the
convention today

8. Energy gets supplied by the battery
Energy gets used up by circuit components

9. • Symbol: V
• SI-Unit: Volt (V)
• Formula : 𝑉 =
𝑊
𝑄
Where V = Potential difference (V)
W = Work done/energy
transferred (J)
Q = Charge transferred (C)
The electrical work done per unit charge

10. Measured with:
Voltmeter

11. Electromotor Force:
The maximum amount of electrical energy that
a battery can supply to the charge that flows
through it

12. V
Measured across the poles of the battery when
switch is open (no current)

13. 10 J energy is transferred when 5
Coulomb charge moves from point A to
point B. Calculate the potential difference
between the two points.

15. Number of particle being pushed through the
circuit

16. The rate at which charge flows
• Symbol: I
• SI-Unit: Ampère (A)
• Formula : 𝐼 =
𝑄
∆𝑡
Where I = Current (A)
Δt = Time (s)
Q = Charge transferred (C)
1 Ampère is the current when 1 Coulomb
charge moves past a point in 1 second

17. Measured with:
Ammeter

18. It takes 5 C charge 2 min to move from
point A to point B. Calculate the current
in the wire.
Calculate the current if 10 J energy is
converted to heat by a lightbulb in 50 s.
The potential difference over the ends of
the lightbulb is 5 V.

19. Magnified representation of a wire
+
+
+
+
+
+
+ +
+ +
+
+
+
+ +
+
+
+
+
+
+ +
+
+
+
+
+
• Delocalized electrons collides wit positive
atomic rests
• Causes Resistance
Tendency to inhibit the flow of electrons

20. Resistance increases if temperature
increases
Resistance decreases if thickness
increases

21. Resistance increases if length increases
Different materials
does not conduct
electricity to the
same extent

22. The relationship of the potential difference (V)
across a component to the current (I) through
that component
• Symbol: R
• SI-Unit: Ohm (Ω)
• Formula : 𝑅 =
𝑉
𝐼
Where R = Resistance (Ω)
V = Potential difference (V)
I = Current (A)

23. A conductor has a resistance of 1 Ω if a current
of 1 A flows through it while the potential
difference across the ends of the conductor is
1 V
V
I R

24. The ammeter
reading is 2 A
and the
Voltmeter
reading is 10 V.
a) Calculate the resistance R.
b) What is the emf of the battery?

25. Resistors in series act as voltage dividers
while the current stays the same
𝑉𝑇 = 𝑉1 + 𝑉2

26. Advantage:
Lowers electricity usage

27. 𝑅 𝑇 = 𝑅1 + 𝑅2 + 𝑅3
𝑉𝑇 = 𝑉1 + 𝑉2 + 𝑉3
𝐼 𝑇 = 𝐼1 = 𝐼2
V
I R

28. Each cell has an emf of 10
V. The resistors have the
following resistances:
R1= 3 Ω; R2 = 2 Ω; R3 = 5 Ω
Calculate:
a) The total
voltage
b) Total
resistance
c) Ammeter
Reading
d) The readings
on each of
the
voltmeters

29. Resistors in parallel act as current dividers
while the voltage stays the same

30. Advantage:
If one lightbulb fuses the other will still work

31. 1
𝑅 𝑇
=
1
𝑅1
+
1
𝑅2
+
1
𝑅3
𝑉𝑇 = 𝑉1 = 𝑉2 = 𝑉3
𝐼 𝑇 = 𝐼1 + 𝐼2 + 𝐼3
V
I R

32. Each cell has an emf of
1,5 V. The ammeter
readings are as follows:
A1= 1 A; A2 = 2 A
Calculate:
a) The total voltage
b) Total resistance
c) The readings on
each of the
voltmeters
d) Each of the
resistances

33. Resistor in series with parallel connection
1
𝑅 𝑃
=
1
𝑅2
+
1
𝑅3
𝑉𝑇 = 𝑉1 + 𝑉𝑃
Calculate Rp
𝑉𝑃 = 𝑉2 = 𝑉3
𝑅 𝑇 = 𝑅1 + 𝑅 𝑃
Calculate RT

34. Resistor in parallel with series connection
1
𝑅 𝑇
=
1
𝑅 𝑠
+
1
𝑅3
𝑉𝑠 = 𝑉1 + 𝑉2
Calculate Rs
𝑉𝑇 = 𝑉𝑠 = 𝑉3
𝑅 𝑠 = 𝑅1 + 𝑅2
Calculate RT

36. The potential difference across R1 is 10 V and
the reading on A1 is 0,4 A. The resistances of
R2 and R3 is 45 Ω and 157,5 Ω respectively.
a) What is the reading on V1 if switch S2 is
open?
b) What is the potential difference over the
battery if switch S2 is open?
Both switches are now closed.
c) Calculate the resistance of R1.

37. d) Calculate the total resistance.
e) What is the reading of V1?
f) What is the readings on A2 and A3?
g) What is the current through R3?
The switch S2 is now open.
h) What is the new readings on A1 and V1?
i) How did the voltage across resistor R1
change? Explain why

38. V1
R1 R2
R3
V2
V3
Vs

39. V1
R1
R2
R3
V2
V3
VT
I1
I2
I3
IT

40. A
V
R

41. V1
R1 R2
R3
V2 V3
VT
I1 I2
IT IT

42. A1
R1
R2
R3
A2
A3
S1
V1
S2
24 V