Basic Electricity, physics

1. Electricity
Ohms Law, Circuits
Series & Parallel Circuits

2. Electricity (Circuit)

3. Circuit Symbols

4. R – Resistance ( )
IRV 
Ohms Law

I– Current (Ampere Amps)
V - Voltage( Volts V )

5. What is R in Diagram A?
Ohms Law
What is R in Diagram B?

6. Ohms Law
Volts (V) Current (Amp) Total Resistance (Ω)
1.5 V 3 Ω
3.0 V 6 Ω
6.0 V 5 Amp
5 Amp 7 Ω

7. Resistivity
Resistivity – the resistance of conductors to flow
of current.
What could be the factors about conductors that
affect flow of current?
– Type of material
– Length
– Cross-sectional Area

8. Resistance of Conductor
A
L
R 
areasectional-cross-
conductorofLength
materialofyresistivit
A
L 


9. Resistivity of Some Conductors
Material Resistivity (Ω-m)
Silver 1.59 x 10-8
Copper 1.7 x 10-8
Gold 2.4 x 10-8
Aluminum 2.8 x 10-8
Polyethylene 108 -109
Glass 1010 - 1014
Hard rubber 1013

10. Series
Equivalent Resistance Re is equal to the
sum of the resistance of each resistor

11. Series
321 VVVVbattery 
Voltage of Circuit is equal to the sum
of voltage drops across each resistors.

12. Series
321 IIIIbattery 
Current supplied by the battery is equal to
the current that passes through each resistor

13. Analysis of Circuit

14. Parallel

15. Parallel
321 IIIItotal 

16. Parallel
321
1111
RRRRe


17. Problem:
A parallel circuit contains 2 resistors:
2Ω and 4Ω. The battery carries 24 V.
321 VVVVbattery 
Obtain Re , Ibattery , V1 ,V2 and I2
Parallel