Science: Lesson 3

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Describe a Series circuit

-All parts are connected in a row that forms one path for the electric charges to follow -Current is the same for all loads -One bulb burns out-->circuit opens-->charges can't flow-->all bulbs go out

What is a common energy source for a circuit?

A battery

What do fuel cells, batteries, and solar cells have in common?

All sources of DC

Describe DC

Always flows in same direction -Generated by batteries (flashlights, cars, cameras)

Where does a compass point and why?

Always point North b/c the South pole of metal inside compass is attracted to Earth's North pole

Where does a magnetic field occur in relation to an electrified wire?

Around the entire length of the wire

When an electric current runs through a wire, a magnetic field is induced _______?

Around the wire

Which of the following atoms is considered neutral?

Atom with 5 protons and 5 neutrons

Why is static electricity not useful as a power source?

Because all energy is released at once in static electricity

Magnetic force

Bring two magnets together-->exert a push or pull on each other

Transformers

Device that relies on electromagnetic induction-->uses induction to increase or decrease the voltage of AC

Load

Device that uses electrical energy to operate

Describe Fields

Earth's inner structure produces its magnetic field --Charged particles move in the liquid and form a magnetic field-->constant rotation keeps Earth magnetized

What is the relationship between electricity and magnetism?

Electricity is a form of magnetism

Lightning is a form of static electricity. What can you infer about what happens when lighting strikes the ground?

Electrons are transferred from the clouds to the ground

What causes the shock you receive when you touch a doorknob?

Electrons being pulled from one surface to another

Magnetic poles

Ends of magnets (N or S)

What are the three components of a circuit?

Energy source, conductor, and receiver

Which of the following is a true statement?

Faraday built on Orsted's discoveries to describe electromagnetic induction

Define current.

Flow of electrons (HOW FAST) -measured by how many electrons pass a point during each second (amp, A) -AC: comes from outlet; different directions -DC: comes from battery; one direction

Which of the following devices is most likely to contain an electromagnet? -Stove, flashlight, fridge, watch

Fridge

You're going camping, and you need a source of electric current. So, you guy a gasoline powered ___.

Generator

Aurora

Glow of particles interacting with atoms in the air-->cause visible light

How do you read electric meters?

Go clockwise or counterclockwise -Go with lower number (arrow between 6 and 7, go with 6)

How are the magnetic domains of a magnet different from the domains of an ordinary piece of metal?

In a magnet, the domains all point in the same direction; in the ordinary piece of metal, they're all jumbled up

How is variation measured?

In degrees

If you have an electromagnet, how can you make its magnetic field stronger?

Increase the strength of electric current

What can you infer about magnetic domains from the fact that they are arrangements of atoms

Individual domains are extremely small

Which of the following metals can be magnetized?

Iron

Electromagnet

Iron core wrapped around with electrical wire -Made by wrapping a solenoid around an iron core-->Combines magnetic field of solenoid with magnetic field of magnetized iron core

What can you infer about iron from the fact that most compass needles are made from it?

It can be easily magnetized

What are electrons?

Negatively charged subatomic particles

When does a compass needle point south?

Never; a compass needle always points north

What are the two poles of a magnet called?

North and South

Grounding

Providing a path that allows charges to flow into the ground

What role does adhesion play in static electricity?

Pulls electrons from one surface toward another

Electromagnetism

Relationship between electricity and magnetism -->happens when electric currents and magnetic fields interact with each other

What can you infer about this source of electricity?

Source of AC

Magnetic field

The area surrounding a magnet where magnetic forces can be detected

Static Electricity

The buildup of electric charge on an object

Two electromagnets contain the same types of magnets and wires. But the magnet in the first moves much faster than the second. Therefore ________

The first electromagnet has a more powerful current than the second

Why does a compass needle point in the direction it does?

The needle lines up along Earth's magnetic field

How could you use a compass to travel due west?

Travel in the direction 90 degrees to the left of where the needle points

Describe Friction

Two objects rubbing together-->Causes transfer of electrons between objects

Electric Generators

Use Induction to change mechanical energy into electrical energy

Electromagnetic induction

Using a magnetic filed to create an electric current in a wire

How does a generator create current?

Using an electromagnet

When will a circuit breaker trip?

When a very strong current passes through it

Which of the following are sources of mechanical energy?

Wind and fossil fuels

Describe a Parallel Circuit

-Electric charges have more than one path that they can follow -Loads are connected side by side-->any bulb can burn out without opening the circuit -Can have different currents-->All loads experience same voltage

Describe Domains

-Groups of atoms form tiny areas called domains -N and S poles of atoms in domain line up and make strong magnetic field -Domains point toward same direction-->form magnetic field --In other materials, there are no domains to line up b/c atoms have no magnetic fields

What is the purpose of the Van de Graaff generator?

-Places charge on dome -Uncharged object touches dome-->Becomes charged by contact

How do electromagnets differ from regular magnets?

-They can be turned on and off -Their polarity can be reversed -Their strength can be changed

What is a solenoid?

A coil of wire that carries an electric current, producing a magnetic field -more loops=stronger magnetic field

Solenoid

A coil of wire that carries an electric current, producing a magnetic field-->more loops=stronger magnetic field

Electric circuit

A complete, closed path through which electric charges can flow-->Form a loop

A flow of electrons through a conductor is called _____?

A current

Galvanometer

A device that measures the strength and direction of an electric current in a wire-->contains electromagnet

What causes lightning?

A difference in electrical charge

Which of the following devices is most similar to a compass?

A global positioning system

What happens when electricity flows through an object?

A magnetic field is created

Electrical conductor

A material through which charges can move freely

Electrical insulator

A material through which charges cannot move easily

If a substance has an excess number of electrons on its surface, what type of charge does it have?

A negative charge

What does the earth have in common with a bar magnet?

A north and south pole

Describe Force

A push or pull exerted on an object in order to change the motion of the object; force has size and direction

What do you need to build a working electric motor?

A source of electricity

Semiconductor

A special class of materials that conduct electric charge better than insulators but not as well as conductors

What device opens and closes an electric circuit?

A switch

Define Induction

A way of rearranging the charges within an object without touching it

Voltage

Amount of work required to move each unit of charge between two points-->expressed in volts (V)-->sometimes called electric potential

What is static electricity caused by?

An imbalance of positive and negative charges

Which term best describes a compass? -A complicated device, a device that's difficult to use, an unsophisticated device, an ornate device

An unsophisticated device

Define Electric Force

Any two charged objects exert a force on each other

Place these events in sequence: A) Voltage decreased by transformer B) Voltage increased by transformer C) Electrical current enters home

B, A, C

How can you create a magnetic field?

By running a current through a wire

Electric motor

Changes electrical energy into mechanical energy-->Runs on AC or DC

What is the function of every generator on Earth?

Changing mechanical energy into electrical energy

Describe Conduction

Charged object and uncharged object touch-->charged object transfers charge to touched area

Electric discharge

Charges that build up as static electricity leaving the object

How is the compass affected by the Earth?

Compass is affected by earth's magnetic field

Why are paperclips attracted to magnets?

Contain iron

In physics, to "induce" something is to _____?

Create it

What is the major difference between static electricity and current electricity?

Current electricity involves a flow of electrons; static electricity involves a single transfer of electrons

How does AC differ from DC?

DC flows in same direction; direction of AC switches back and forth

Amperes

Electric current expression-->Symbol is A

Electric Energy

Energy of electric charges

How might life be different if we didn't have compasses?

European explorers might never have made it to North and South America

Where might you find an electromagnet?

In an electric motor

What can you infer about any object that gives you a tactic shock when you touch it?

It's a conductor

What does a magnetic field look like?

It's invisible

What is the simplest requirement for an electromagnet?

Length of electrified wire

Magnet

Material that attracts iron or objects made of iron

Ferromagnetic

Material that can be turned into a magnet

In most electrical circuits, the pathway is made of _____?

Metal

What happens when you touch a metal doorknob after rubbing your shoes on the carpet?

Millions of electrons go from your finger into the doorknob

What is one possible reason why it's a good idea to conserve electricity?

Often produced by burning fossil fuels, which are a polluting, non-renewable resource

Define resistance.

Opposition to flow of electricity -Good conductors have low electricity -Depends on temp, length, and thickness of wire -Measured in Ohms

Resistance

Opposition to the flow of electric charge-->expressed in ohms

Why would the domains of a paperclip line up?

Paperclip has been exposed to a magnetic field

Define Electric Charge

Property that leads to electromagnetic interactions between the particles that make up matter

How are electrons different from protons and neutrons?

Protons and neutrons exist inside atomic nuclei; electrons orbit atomic nuclei

What is the function of a power source in a circuit?

Provides a steady flow of electrons

Describe AC

Repeatedly changes directions -Comes from outlets (toasters)

What effect will the north pole of one magnet have on the north pole of another magnet?

Repulsive

To change the polarity of an electromagnet, you would ____?

Reverse the current's direction

How does rubber differ from most metals?

Rubber is a good insulator; most metals are good conductors

What is the main function of a turbine?

Spinning

What is a current?

Steady flow of electricity

Which word best describes electricity as it occurs in nature?

Sudden

Which of the following materials is an insulator? -Foil, sweater, coin, or pool flotation thing

Sweater

Define Ion

The atoms overall positive or negative charge

How would you compare the magnetic field generated by a simple length of wire to the magnetic field generated by a coil of wire?

The coil generates a stronger magnetic field

What is variation?

The difference between where a compass points and the Geographic North Pole

What might happen if transformers didn't exist?

The electricity in your house might have an extremely high voltage

What happens if you disconnect a circuit from its positive terminal?

The electrons stop flowing, and the current stops

Electric current

The rate of flow of electric charges

What does lightning have in common with the shock you receive when you touch a doorknob?

They're both forms of static electricity

How does electricity travel from power plants to your house?

Through transmission wires

How might an electric motor be used in a washing machine?

To make the machine spin

Which of the following is an example of a load? -Outlet, battery, toaster, circuit

Toaster

Describe Induction

Way of rearranging charges within an object without touching it

What might happen if wires weren't insulated?

We'd be in danger of harm from electric shocks

Define voltage.

measure of push applies to force electrons to move through a circuit (HOW MUCH IS BEING PUSHED) --Also called potential difference Higher the voltage, the more energy each electron carries and the more work it can do


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