Negative charges in an atom are called electrons

Negative charges in an atom are called electrons ______.

Rules 1. Like charges repel one another 2. Unlike charges attract one another 3

What kind of electricity can be caused by rubbing two materials together?

When you rub a balloon with a cloth, _____ negative charges are knocked off the cloth and are collected onto the balloon. This makes the balloon have a negative charge. _____

The van de Graaf generator (large silver ball) deposits electrons on the ball. When a person places their hand on the ball and the machine is turned on, electrons are transferred to and collected on the person touching the silver ball. Why do you think this machine affects the hair of the children in the picture?

What is a discharge of static electricity in the atmosphere called?

Lightning occurs when negative charges the ______ in the thundercloud build up and jump to the positively ______ charged ground.

What is an electric shock? • When the electric current enters your body. • The amount of current depends on whether it is fatal or not.

What are some things you should know about lightning safety? • Take shelter inside if you hear thunder or see lightning. • Avoid open fields and high places of elevation. • Avoid isolated objects (trees in a field) • Avoid metal objects (bleachers, picnic shelters) and bodies of water • If you cannot go inside then assume the “duck-cover position”

What are the rules about electrical forces? • The positively charged protons in the nucleus attract the negatively charges electrons in the energy levels and hold them in place. • The closer the objects are that are attracted to each other the stronger the electrical forces. • Like charges repel and unlike charges attract.

What is an electric field? • Electric forces exerted at a distance between two objects create the electric field.

What is grounding? • Grounding is the use of a conductor to send a large electric discharge into a substance that cannot be harmed instead of following the path that it would normally follow. • Example: sending lightning into the Earth instead of into a house

What kind of electricity is caused by a continuous flow of electrons?

Current • Flow of electrons through a conductor • Measured in amperes (A) 15

Voltage • A difference in electrical potential • Measured in volts 16

What is the path that electricity flows through called?

A circuit must be closed to allow _____ the flow of electricity. Electrons flow thru a circuit because of the applied voltage across the circuit (Ohm’s Law)

What is the difference between an open circuit and a closed circuit? A closed circuit is one in which the pathway of the electrical current is complete and unbroken. An open circuit is one in which the pathway of the electrical current is broken. A switch is a device in the circuit in which the circuit can be closed (turned on) or open (turned off).

How many pathways does a series circuit have?

Series Circuit • Current flows through a single path. 21

Series Circuit • If the path is broken at any point, current flow stops. • Ex: Old Christmas lights 22

How many pathways does a parallel circuit have?

Parallel Circuit • Current flows through multiple paths. 24

Parallel Circuit • If one path is broken, current continues to flow through other paths. • Ex: House wiring

What can be used to control the flow of electricity?

What do we call materials that allow the flow of electricity?

What do we call materials that do not allow the flow of electricity?

What is a conductor and insulator? A conductor is a material which allows an electric current to pass. Metals are good conductors of electricity. An insulator is a material which does not allow an electric current to pass. Nonmetals are good conductors of electricity. Plastic, glass, wood, and rubber are good insulators

What is a poor conductor called?

Resistors allow electrical energy to be ______ changed into other forms of energy.

Resistance • The opposition to the flow of electrons through a conductor • Measured in ohms ( ))

Ohm’s Law • Relationship between voltage, current, & resistance • Current = voltage resistance or I = V / R

Direct Current (DC) • Electrical current that flows in only ONE direction • Ex: Batteries

Alternating Current (AC) • Electrical current that changes direction as it flows • Ex: Homes wired to an electrical power grid

In DC, the electrons flow steadily in a single direction, or "forward. "

In AC, electrons keep switching directions, sometimes going "forwards" and then going "backwards. "

Name three types of energy that electricity can be changed into. Heat, light, and mechanical energy

Electrical Power and Cost • Electrical power is measured in watts (W) • Electricity is calculated in Kilo. Watt-Hours

How is the cost of your electricity determined? • Power is the rate at which energy is used, or the amount used per second. • Electricity is sold in kilowatt hours (1, 000 watts). • 1 k. W is the amount of electrical energy for 1 hour. • 10 100 -W light bulbs for 1 hour or one 100 -W bulb for 10 hours.

What is the area of magnetic force called?

Electric current creates a magnetic field. _______

Magnetism • Like poles attract • Unlike poles repel • Magnetic fields are strongest near the poles.

Magnetic Fields • Field flows North to South

What do you make if you put together a closed circuit and wrap the wire around an iron bolt? Electromagnet

How can you make an electromagnet stronger? You can wrap the wire around the iron bolt more times.