CHAPTER 7 7.2 SERIES AND PARALLEL CIRCUITS

CHAPTER 7:ELECTRICITY
AND MAGNETISM

7.2 FLOW OF ELECTRIC CURRENT
IN A SERIES CIRCUIT AND
PARALLEL CIRCUIT

04-Jul-21 Prepared by:Teacher Ida Marwani binti Abdullah 1

Electrical Circuit Components

A complete electric circuit is made up of electrical components which are represented by symbols.

Electrical Symbol Electrical Symbol
component component

Switch Bulb

Dry cell Resistor

Voltmeter Fuse

Galvanometer Variable
Ammeter resistor

TYPES OF Types of
ARRANGEMENTS OF arrangement

ELECTRICAL
COMPONENTS

Series circuit

Series circuit Parallel
circuit

Parallel circuit

04-Jul-21 Sample Footer Text 3

D I F F E RE NC E S B E T W E E N S E RI E S
C I RC UI T A ND PA RA L L E L C I RC UI T

Series circuit Parallel circuit

There is only one path for current to There are several paths for current to

flow through the bulb flow through the bulbs

Bulbs do not glow as bright as those Bulbs are brighter than those

connected in parallel connected in series

If one bulb is fused, the other bulbs If one bulbs is fused, the other bulbs
do not light up because the circuit still light up because current still
become incomplete. flows through the other bulbs.

04-Jul-21 Sample Footer Text 4

Calculation of Current, Voltage and Resistance in Series
Circuit

Ohm’s Law Current
I = I1 = I2 = I3

Voltage
V = V1 + V2 + V3

Resistance
R = R1 + R2 + R3

Example:

Two resistors, R1 and R2 are
connected in series in a circuit
as shown in the figure.
Calculate:
a) The effective resistance, R
b) The current, I in the circuit
c) The voltage, V1 and V2

Example: R = R1 + R2
=2Ω+2Ω
Two resistors, R1 and R2 are =4Ω
connected in series in a circuit
as shown in the figure.
Calculate:
a) The effective resistance, R
b) The current, I in the circuit
c) The voltage, V1 and V2

a) R = 4 Ω

Example: I=V÷R
=6÷4
Two resistors, R1 and R2 are = 1.5 A
connected in series in a circuit
as shown in the figure.
Calculate:
a) The effective resistance, R
b) The current, I in the circuit
c) The voltage, V1 and V2

a) R = 4 Ω

b) I = 1.5 A

Example: V1 = I1 x R1 V2 = I x R2
= I x R1 = 1.5 x 2
Two resistors, R1 and R2 are = 1.5 x 2 = 3V
connected in series in a circuit
as shown in the figure. = 3V
Calculate:
a) The effective resistance, R
b) The current, I in the circuit
c) The voltage, V1 and V2

a) R = 4 Ω

b) I = 1.5 A

c) V1 = 3V ; V2 = 3V

Calculation of Current, Voltage and Resistance in
Paralell Circuit

Current Ohm’s Law
I = I1 + I2 + I3

Voltage
V = V1 = V2 = V3

Resistance

= + +

R R R R3

Example: 3
3
Two resistors, R1 and R2 are
connected in parallel in a circuit
as shown in the figure.
Calculate:
a) The effective resistance, R
b) The voltage, V
c) The current, I in the circuit

Example:

Two resistors, R1 and R2 are 3
connected in parallel in a circuit 3
as shown in the figure.
Calculate: 2xR=1x3
R = 1 x 3 ÷2
a) The effective resistance, R R = 1.5 Ω

b) The voltage, V

c) The current, I in the circuit

a) R = 1.5 Ω = +

R R R

= +

R 3 3

= 2

R 3

Example: 3
3
Two resistors, R1 and R2 are
connected in parallel in a circuit
as shown in the figure.
Calculate:
a) The effective resistance, R
b) The voltage, V
c) The current, I in the circuit

a) R = 1.5 Ω V = 6V
b) V = 6 V

Example: 3
3
Two resistors, R1 and R2 are
connected in parallel in a circuit
as shown in the figure.
Calculate:
a) The effective resistance, R
b) The voltage, V
c) The current, I in the circuit

a) R = 1.5 Ω I=V÷R
b) V = 6 V = 6 ÷ 1.5
c) I = 4 A = 4A

Example: 3
3
Two resistors, R1 and R2 are
connected in parallel in a circuit
as shown in the figure.
Calculate:
a) The effective resistance, R
b) The voltage, V
c) The current, I in the circuit

a) R = 1.5 Ω I1 = V1 ÷ R1 I2 = V2 ÷ R2 I = I1 + I2
b) V = 6 V = 6÷ 3 = 6÷ 3 =2+2
c) I = 4 A = 2A = 2A = 4A

Advantage & Disadvantage of a Series
Circuit

Advantages Disadvantages

a) The brightness of the bulbs can be a) Damage to any part of the circuit will

increased by connecting more cells to the stop the flow of current. When the circuit

circuit. is broken, the whole circuit becomes

incomplete.

b) Each bulb lights up with equal b) When more bulbs are added to the
brightness. series circuit,the bulbs become dimmer
because the electrical energy is shared by
many bulbs.

Advantage & Disadvantage of a
Parallel Circuit

Advantages Disadvantages

a) Electric current can still flow in a) The brightness of bulbs does
the circuit through other paths if not increase when more cells are
one of its components is damaged added to the circuit

b) Each electrical component can b) The dry cells become weak
be controlled separately by quicker when more bulbs are
switches connected in parallel