SCIENCE FORM 2 CHAP 7 (7.2)

CHAPTER 7:

Electricity and magnetism

7.2 flow of electric current in a series
circuit and parallel circuit.

Electric current

• Electricity is the flow electrical charges
(electrons) in one direction.

• The continuous flow of electrons form an
electric current.

To observe the evidence of the flow of
electric current

• Galvanometer
• Van de Graaff

Van de graff

Electric current, voltage and resistance.

Terms Meaning

Voltage (V): The energy needed to move the
electrical charges from one point to
another.

Electric current (I) the continuous flow of electrons in an
electric circuit.

resistance (R) the property of resisting or opposing
the flow of electrical charges through it.

Electric current, voltage and resistance.

• Electric current flows from
positive terminal to negative
terminal.

• electrons flow from negative
terminal to positive terminal.

Electric Current, I

• Measured with an ammeter.
• Unit: ampere (A)

-An ammeter is connected in series to
the electric circuit.

The positive and negative terminals of
the ammeter are connected to the
positive and negative terminals of the
electric supply (battery).

To measure Voltage V

• Measured with a voltmeter.
• Unit: volt (V).

A voltmeter is connected in parallel to
the electric circuit.

The positive and negative terminals of
the ammeter are connected to the
positive and negative terminals of the
electric supply (battery).

Relationship between current, voltage
and resistance

• Ohm’s Laws states that the current flowing
through a conductor is directly proportional

• to its voltage.



Flow of electric current in a electric
circuit

• Electric current requires a complete path to
flow known as electric circuit.

• 2 types of circuit:

-series circuit

-parallel circuit.



PARALLEL AND SERIES CIRCUIT

• Series circuit parallel circuit

Parallel circuit

Series circuit



NUMERICAL PROBLEM

• Textbook page 157…

R
V

SERIES CIRCUIT

1-EFFECTIVE RESISTANCE, R = RI+R2+R3

R = RI+R2+R3
= 1ռ+3ռ+5ռ
= 9ռ

2-CURRENT, I = V/R
I = V/R
= 9 V/9ռ
=1A

3- VOLTAGE, V = VI+V2

V = 9V

Textbook page 157 Question 3
TRY DO IT!!