140 likes | 230 Views
Explore the basics of electric current, resistance, and Ohm's Law to grasp the fundamentals of electricity. Learn about the flow of electric charge, units of measurement, factors affecting resistance, and the relationship between voltage, current, and resistance.
E N D
There are 72 names of French mathematicians, engineers and scientists on the side of the Eiffel tower
Electric Current (I) • The flow of electric charge • Unit- Amperes (Symbol A) • An Ampere - 1 coulomb of charge second (1 coulomb = 6.24 billion billion electrons) Measured using an ammeter
Electric Current • When no electricity is applied…free electrons (conducting electrons) are always moving in random motion • But when the switch is closed the free electrons of the conductor are forced to drift toward the positive terminal under the influence of the electric field
Resistance- helps to control the amt of current • Opposition to the passage of an electric current through that conductor. • Unit- ohm (Ω)
Resistance (R) • The resistance of an object depends primarily on 3 factors: • 1) What the material is made of • Place in order of least resistance the following materials: • Aluminum, gold, silver, glass, copper • Silver • Copper • Gold • Aluminum • Glass
The resistance of an object depends primarily on 3 factors: • 2) It’s thickness • A thick copper wire has lower resistance than an otherwise-identical thin copper wire.
Not a good idea • 3) It’s length • For example- a long copper wire has higher resistance than a short copper wire.
Ohm’s Law • Current = Voltage Resistance Current (amps)= Voltage (volts) Resistance (ohms) The greater the voltage the _ the current The greater the resistance the _ the current
Resistance • A typical lightbulb has a resistance of 100 Ώ • An iron or toaster has a resistance of 15-20 Ώ The lower resistance permits a large current, which produces a considerable amount of heat