1. Electricity and Magnetism

2. Electric Charge
Net electric charges result from an imbalance of protons and electrons
More electrons than protons = negative charge
More protons than electrons = positive charge
Like charges repel and opposite charges attract
A neutral object is attracted to a charged object

3. Transfer of Electric Charge
Charge results when electrons are transferred; protons always stay in the nucleus
Induced charge- charges redistributed without changing net charge
Charged by contact- electrons are transferred from a charged object to a neutral object
Charged by friction- electrons transfer as surfaces rub together, results in static electricity

8. Ohm’s Law Resistance = 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 𝑐𝑢𝑟𝑟𝑒𝑛𝑡 or R = 𝑉 𝐼
Voltage, in volts (V), measures potential difference in charge
high when opposite charges are far apart or like charges are close together; low when opposite charges are close together or like charges far apart
Current is the rate at which charges move
Measured in amperes or amps (A)
Resistance measures how much friction in a material will slow down the movement of charges (lower in conductors than insulators)
Measured in ohms (Ω)

9. R = 𝑉 𝐼
The headlights of a typical car are powered by a 12 V battery. What is the resistance of the headlights if they draw 3.0 A of current when they are turned on?
A 1.5 V battery is connected to a small light bulb that has a resistance of Ω. What is the current in the bulb?
The current in a video game is 0.50 A. If the resistance of the game’s circuitry is 12 Ω, what is the voltage of the battery?

10. Circuits
When a load, such as a light bulb, is connected across a source of voltage it is called a closed circuit
Without a complete path, it is called an open circuit

11. Series vs. Parallel Circuits
Series circuits form a single pathway for charges to flow
If one element is removed, the circuit will not work
Adding more bulbs increases resistance (Rt= R1 + R2 + R3….)
Parallel circuits have two or more paths for electricity to flow
If one pathway is open, the others will still work
Adding more bulbs decreases resistance ( 1 𝑅 𝑡 = 1 𝑅 𝑅 𝑅 3 …..)

12. Total Resistance

13. Total Resistance

14. Total Resistance

15. Total Resistance

16. Magnetic Fields
Magnetism is caused when electrons align in the same way.
Magnets have a north and south pole.
Like poles repel; opposite poles attract.
Magnetic field lines form loops from north to south pole.
The field is strongest near the magnet’s poles.

17. Earth’s Magnetic Field
Compasses align to earth’s magnetic field.
Earth’s geographic north pole is actually its magnetic south pole. This is why compass needles point north (opposites attract).

18. Electromagnets Moving electric charges produce magnetism
A solenoid is a coil of wire with an electric current running through it.
More loops of wire = stronger magnetic field
More current = stronger magnetic field
A rod of magnetic material like iron can be inserted through the solenoid to increase its strength and create an electromagnet.