Science test physic

The three subatomic particles in an atom

• Electrons

• Protons

• Neutrons

Electron electric charge

(-)

Proton electric charge

(+)

A neutral atom contains the same number of what and what?

A neutral atom contains the same number of protons and electrons.

what subatomic particles do atoms lose or gain to become electrically charged?

Atoms loss or gain electrons to become electrically charged.

Neutral objects become positive by ___ electrons

Neutral objects become positive by losing electrons

Neutral objects become negative by ___ electrons

Neutral objects become negative by gaining electrons

How does an atom become negatively charged

An atom becomes negatively charged when it gains one or more electrons.

Law of attraction and repulsion

Like charges repel each other

Unlike charges attract each other

Charged objects will attract neutral objects

A positively charged object is brought near another positively charged object.

Like charges repel each other

A positively charged object is brought near a neutral object.

Charged objects attract neutral objects

A negatively charged object is brought near a positively charged object.

Unlike charges attract each other

What does the word static mean in reference to static electricity?

The word static mean “not moving” which means that the charge stay in the same area.

Insulator definition and examples

Insulators are substances in which electrons cannot move freely from atom to atom. Examples: Glass, wood, air, plastic, etc.

Conductor definition and examples

Conductors are substances in which electrons pass freely from one atom to another. Examples: Copper, gold, silver, aluminum, water,etc.

Objects become charged when ___ moves from one object to another.

Objects become charged when electrons moves from one object to another.

What are the three ways to electrically charge an object?

1. By Friction

2. By Conduction (Contact)

3. By Induction

Charging by Friction

Start with two neutral objects. The objects are rubbed together. One object is positively charged and the other is negatively charged (electrostatic series).

Charging by Contact

Start with one charged object and one neutral object. The Objects are briefly touched together. The neutral object will end up with the SAME charge as the charged object.

Charging by induction

Start with one charged object and one neutral object. The objects are brought close together without touching. The Neutral object will end up with the OPPOSITE charge of the charged object.

Explain how the electrostatic series is used to determine the charge that will result from the objects in the table below being rubbed together (ie. Charged by friction)

The electrostatic series shows which materials tend to lose or gain electrons when rubbed together. The material higher on the list becomes positively charged, and the one lower becomes negatively charged.

What happens to a neutral object if you touch it with a positive object?

The neutral object will become positively charged

What happens to a neutral object if you touch it with a negative object

The neutral object will become negatively charged

What happens to a neutral object if your bring a negatively charged object close to it?

The neutral object will become positively charged

What happens to a neutral object if your bring a positively charged object close to it?

The neutral object will become negatively charged

rubbing your feet on the carpet while you walk. Friction, contact, or induction

Friction

Getting a shock when you touch a door knob. Friction, contact, or induction.

Contact

Charging the exterior (outside) of an airplane when it is flying through the air. Friction, Contact, or induction.

Friction

The positive charge on the ground when an electrically charged lightning cloud is moving over it. Friction, contact, or induction

Induction

The sparks produced when a wool sweater is pulled off. Friction, contact, or induction

Friction

What could you use if you wanted to determine if an object was electrically charged or not?

You can use a metal-leaf electroscope.

Explain why the leaves of an electroscope move away from each other when a charged object is brought near it.

Both metal leaves will receive the opposite charge of the charged object and will repel since like charges repel.

Will a positively charged balloon stick to a wall just as easily as a negatively charged balloon? Explain why.

A positively charged balloon will stick to a wall just as easily as a negatively charged balloon because both will induce a charge on the wall

Would a negatively charged balloon stick to a metal wall as easily as to a wooden wall? Explain your answer.

a negatively charged balloon wouldn’t stick to a metal wall as easily as to a wooden wall because a wooden wall is an insulator and holds static charges and metal wall will conduct the electrons and not hold the static charge.

What is grounding and what does it do?

Grounding is the process of connecting a charged object to the ground (Earth’s surface).

Define electrical discharge and give one real life example of an electrical discharge.

Electrical discharge is the transfer of static charge from one place to another. Lightning is an example

Explain how the sound of thunder is formed.

The lightning heats the air to temperatures hotter than the sun, causing a rapid expansion of the air around it – this ‘explosion’ of the air creates the sound of thunder.

Why do we usually hear thunder after we see lightning, even though they occur at roughly the same time?

Light travels about a million times faster than the speed of sound.

What should you do if you are outside and you hear lightning?

If you hear lightning and your outside find shelter and if lightning is about to hit you get to the ground and crouch.

If lightning hits a car, the effect is minimal. Explain why.

A car provides a safe path for charge to flow around the passenger compartment and is insulated by its rubber tires.

What if you had the windows rolled up during a thunder storm

If the windows are rolled up and no one inside touches any metal components of the car, and so the effect of a lightning strike is minimal.

What is a lightning rod and how does it work?

A lightning rod is a metal pole with a wire attached to it that runs down to the ground.

How can you ground static charges on a car? On an airplane?

Static charges on a car can be grounded using grounding straps that allow the charge to safely flow to the ground. Airplanes use static wicks to release excess charge into the air while flying, preventing buildup and protecting their system.

Suppose you have a plastic lightning rod that was the same size and design as a metal lightning rod. Would the plastic lightning rod work better than, the same as, or not as well as a metal lightning rod? Explain your answer.

A plastic lightning rod is an insulator and would not effectively pass the electric charge to the ground. The metal lightning rod would because metal is a conductor.

How would a humidifier in a home affect static charge build up? Would you need to use one more in the summer or winter?

A humidifier reduces static charge buildup by adding moisture to the air, which helps prevent charges from accumulating. People needs to use it more in the winter, when the air is dry and static electricity is more common.

While standing on a wooden chair, a student holds her hand on the Van de Graaf generator. As time passes, her hair begins to stand up. Explain what is happening.

When the student places her hand on the Van de Graaff generator, the machine begins to transfer electric charge to her body. Since she is on a wooden chair, she will build up charge and then they repel each other, and that’s why they stand up.

This same student, while standing on the chair, touches a student who is nearby. Explain what will happen and why.

When the charged student (who is touching the Van de Graaff generator) reaches out and touches another student nearby, a sudden discharge of static electricity will occur. This is because the charge built up on the first student’s body now has a pathway to flow to the other student, who is likely neutral or less charged. Then, eventually, they will be both charged.

After this same student touches another student, she touches a wooden desk. Explain what happens and why.

When the student touches a wooden desk, nothing really changes because wood is an insulator and doesn’t allow electricity to pass more easily. As a result, they will still remain charged, and the student’s hair will continue to stand up.

If you wrap plastic wrap on a glass bowl it will cling to the bowl. Use your understanding of static charge to explain why.

Plastic wrap assumes a negative charge relative to glass. That is why cling wrap works well on glass containers.

If you find yourself out in the open during a thunderstorm, you should crouch, keep your feet close together, and stay on your toes. why should you do this?

You should crouch with your feet close together and stay on your toes to reduce your height and minimize contact with the ground, lowering the chance of being struck by lightning.

What did Charles-Augustin de Coulomb discover about electric charges

• The closer two objects are, the strongerthe attraction or repulsionstronger the

• The further two objects are, the weaker the attraction or repulsion

What is the metric unit for electric charge?

the metric unit for electric charge is coulomb

how many electrons adding or removed from a neutral object equals to a coulomb

One coulomb = 6.24 x 1018 electrons added or removed from a neutral object.

safely rules of lightning.

1. Stay or go indoors.

2. Stay away from anything that could conduct electricity.

3. Don’t use any plug-in electrical appliences.

4. Don’t use the telephone during the storm.

5. Stay in your automobile if you are traveling

6. Don’t use metal objects outside

7. Get out of the water

8. If you’re outdoors, seek shelter from lightning!

9. If you can’t find shelter, avoid the tallest objects in the area.

10. When you feel the electrical charge. Drop to the ground immediately!