Download Electricity What you should already know

Electricity – What you Should Already Know
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 Atomic Structure:
 Nucleus
– Protons – positive charge
– Neutrons – neutral
 Electrons – negative charge
 Electrons do the moving – little and on the outside
 Protons and neutrons don’t move
-Tightly bound in the nucleus
-Much bigger mass than electrons
 Electrostatics – charges build up, but don’t flow continuously
 Like charges repel
 Unlike charges attract
 neutral charges neither repel nor attract each other
 a neutral object can attract a - or + charge
 Current Electricity – continual flow of electrons through a conductor
 Conductors – materials that electrons can move through easily
ex. – copper, gold, silver
 Insulatorselectrons can’t move easily
ex. – wood, cotton, rubber, glass
 Current (I) is measured by how many electrons pass a point during each second
 Units: Amperes (A)– amount of current flowing in one second
 Load or resistor – device that uses the electrical energy
Light bulb, heating coils in a toaster,
microwave oven
 Resists the flow of electrons
 Electrical energy converted into heat, light, or mechanical energy
 Voltage (V): the electric potential energy that pushes the electrons; units: volts (V)
 Resistance (R): an property of the parts of the circuit that slow down the electrons; units: ohms (Ω)
3 Types of circuits:
– Parallel circuits – the electrons flow in more than one path to reach each resistor individually
– Series circuits – the electrons flow in only one path passing through each resistor
– Combination circuits – some resistors are in series, some are parallel
Ohm’s Law:
V=IR
(different on equation sheet)
Electrical Power: P=IV
(different on equation sheet)
Units of Power: Watts(W)
1.
What is voltage if current is 1.5 amperes and resistance is 30 ohms?
2.
What is the current flowing through a wire if the resistance is 20 ohms and the voltage is 40 volts?
3.
What is a wire’s resistance if a current of 0.5 amperes flows through a wire and the voltage is 50 volts?
4. Your clothes dryer has 220V running into it and a current of about 18A. How much Power does it use?
5. Which type of circuit are these?