Physical properties of electric current

1. Physical properties of
electric current

2. Objectives:-
❑Identify the components of the electric circuit and the role
and symbol of each component.
❑Find out what is meant by an electric current and how its
generated.
❑Explore the physical properties of an electric current such
as current intensity, potential difference and electric
resistance
❑Predict the relation between current intensity and
potential difference (Ohm’s Law).

3. Warm up
➢ How can we operate all these devices?
➢ What kind of energy these devices need
to operate?
➢ How can connect these devices to the
source of energy?
➢ Can we control the flow of energy or
should it be turned on all the time?

4. The electric circuit:-

6. The role and symbol of each component:-

7. How to draw an electric circuit using
symbols:

8. The electric current:-
The electric current is
generated in electric power
stations that are away from our
houses by hundreds or
thousands of kilometers
How is the electric current
generated ? And what is meant
by an electric current

9. What is an electric current?

10. Electric current: it’s the flow of electric negative charge (electrons) through a
conducting material like the copper wire

11. Physical properties of the electric current:-
• 1 Current intensity( I ) measured in Ampere
• 2 Potential difference( V ) measured in Volt
• 3 Electric resistance( R ) measured in Ohm

12. 1) Current intensity (I) (Ampere)
• It’s the quantity of charges that flows through a across section
of a conductor in one second.
Current intensity=
𝑸𝒖𝒂𝒏𝒕𝒊𝒕𝒚 𝒐𝒇 𝒄𝒉𝒂𝒓𝒈𝒆𝒔(𝒒)
𝑻𝒊𝒎𝒆 𝒊𝒏 𝒔𝒆𝒄.(𝒕)
1 Ampere=
𝟏 𝑪𝒐𝒖𝒍𝒐𝒎𝒃
𝟏𝑺𝒆𝒄𝒐𝒏𝒅

13. Problem:
Calculate the current intensity passing through a across-section
due to the flow of 5400 coulomb for 5 minutes.
Solve in your copybook

14. Now observe what happens to the current intensity in the following cases
➢ If the quantity of charges is doubled and the time is constant
➢ If the time is doubled and the quantity of charges is constant
What do we conclude

15. The electric current intensity is
• Directly proportional to the
quantity of charges
when time remains constant
• Because when the quantity
doubled, the intensity also
doubled.
• Inversly proportional to the time
of charges
when quantity remains constant
• Because when the time doubled,
the intensity decreased to half.

16. Problem: if an electric current of intensity 6 ampere passes
through a conductor in 15 sec. find the quantity of electric charge
that passes through a cross section of this conductor

17. How to measure the current intensity passing
through the circuit?

18. Quick check
➢What are the main components of an electric circuit?
➢The current intensity is measured in………………………. Using a device
called……………………….
➢The intensity is…………………. Proportional to the quantity of charges
while its ……………….. Proportional to the time.
➢The source of the electric current in the electric circuit is………………
while …………… is used to control opening and closing the circuit.
➢The ammeter is connected in ………………. In the electric circuit.