static electricity test (4/30)

The electrostatic force between two charges located 8 meters apart is 0.10 N. What will the force be between these charges when they are located 2 meters apart?

1.6 N

One electron has a charge of negative _ Coulombs.

1.6 x 10 -19

Each electron carries with it the fundamental charge, which is _ Coulombs.

1.6 x 10^-19 (0.00000000000000000016 Coulombs)

Two charges separated a distance of 1.0 meter exert a 2.0-N force on each other. If the charges are pushed to a separation of meter, the force on each charge will be

18.0 N

A 2-C charge and a 4-C charge attract each other with 10 N of force. How much will a 2-C charge and a 12-C charge attract each other when placed the same distance apart?

30 N

Two charges separated by a distance of 1 meter exert a 20-N force on each other. If the charges are pulled to a 2 meter separation distance, the force on each charge will be

5 N

The charge of an electron is -1.6 x 10-19. Find the electric force between an electron and a proton that are 2 x 10-8 m apart. k=9.0 x x109 Nm2/C2

5.8 x 10^-13

There are _ electrons for every negative Coulomb.

6.24 x10^18

Two charges separated by a distance of 1 meter exert a 2-N force on each other. If the magnitude of each charge is doubled, the force on each charge is

8 N

Notes from the Royal Society in 1705 reveal how hard _ tried to stamp his personality and to impress his masters. In November he came up with a rotating glass sphere

Francis Hauksbee

At the dawn of the 19th century in a cellar in Mayfair, the most famous scientist of the time _ built an extraordinary piece of electrical equipment four meters wide twice as long (4m x 8m). It had been created to pump out more electricity than had ever been possible before. It was in fact the biggest battery the world had ever seen.

Humphrey Davy

Electrical research done in Leiden Holland by professor _ is one of the most significant of the 18th century (Leyden Jar or Leiden Jar) and it can still be found in almost every electrical device today (capacitor).

Pieter van Musschenbroek

This is the Royal Society in London in the early 1700s after years in the wilderness Isaac Newton finally took control of it after the death of his enemy _.

Robert Hooke

Static electricity occurs when an object obtains _, creating an imbalance that wants to be returned to equilibrium.

a net amount of positive or negative electric charge

In this diagram of a charged insulator, where the left side is going to have a negative charge, the right side is going to have _.

a neutral charge

Charge carriers in a metal are electrons rather than protons, because electrons are

all of the above

The gravitation and electrostatic forces work in totally different ways. The force of gravity is _. But the electrostatic force is _

always attractive. .... either attractive or repulsive.

_ causes charged particles to move.

an imbalance of electrical charge

If it is _, all of those charges, those electrons, are fixed. So we can add charges to one part of it and it does not mean the rest of it has to get charged.

an insulator

In _, the charges are going to be fixed wherever you put them.

an insulator

In _, like in _, all electrons are fixed, they can move a little bit, but they are always going to be stuck to that proton of the atom of which they are part.

an insulator, .... plastic or in glass

Protons and electrons

attract each other

Coulomb's law is essentially identical to Newton's law of universal gravitation. The only difference is that the electric force can be attractive or repulsive depending on the signs of these terms and the resulting sign on the force, while gravity is always _.

attractive

Electrical polarization occurs when

charge distribution in a neutral molecule separates.

Say you have a glass rod that's electrically neutral, and you rub it with a cloth. That physical interaction causes electrons to hop onto the cloth, leaving the rod with an overall positive charge. This is called _.

charging by friction

Electrical forces between charges are strongest when the charges are

close together

_, we are touching two objects so electrons can move.

conduction

So, an object can be charged through friction, like rubbing your hair on a balloon, or it could also be conduction, touching another charged object, or charging by induction. Depending on what that charged object is, maybe it is a _, then the electrons in there are mobile, they can move around, and that charge is going to start to dissipate or at least move within the object itself.

conductor like metal

A substance that can easily transfer electric charge is a _. One that can't is an _.

conductor, insulator

_ allow electricity to flow through them. Like the human body or metals.

conductors

The SI unit of charge is the

coulomb

Opposite charges attract one another because of the electric force. This is outlined in _, which states that the magnitude of the electric force between two objects is equal to the constant k times the charge on one object times the charge on the other divided by the square of the distance between them.

coulomb's law

Coulomb's law says that the force between any two charges depends

directly on the size of the charges, inversely on the square of the distance between the charges (both A and B)

The force between two charged particles is equal to the product of the two charges times k, divided by the _.

distance between them squared

The fundamental force underlying all chemical reactions is

electrical

Ancient Greeks rubbed amber which they called _ to get small shocks.

electron

When we are rubbing an object we can actually pull _ off or add _ to it.

electrons

The _, which are the essence of electricity, are easily transferable and it is the transfer of _, in this case from your hair to the balloon that generates electric charge in previously neutral materials.

electrons, electrons

The ancient Greeks actually rubbed fur against amber and discovered that the amber would then attract hair and feathers. We know that the fur got _ during this process, and the amber was left with an overall _ charge.

electrons, positive

A good way to study induction and conduction, in the science lab, is to use something called an _.

electroscope

A material is a good insulator if outer electrons of atoms in the material are free to roam around.

false

Electrical forces are strong, but in comparison, gravitational forces are stronger.

false

In solid materials, protons stay fixed, but some electrons are free to move around. These moving electrons are called _.

free electrons

Materials that are conductors, like _, let free electrons move freely throughout the solid, while insulators, like _, hold on to them tightly, limiting their flow.

gold, rubber

The more densely packed the field lines are in a particular region, the _ the strength of the field.

greater

The reason a charged balloon will stick to a wall is that

induced opposite charges in the wall are closer than other wall charges.

Bring a charged object near a conductor and then momentarily touch the conductor. This demonstrates charge by

induction

Objects can be charged by

induction, friction, and touching (all of the above)

_ held electric charges within them and wouldn't let it move. Like silk, glass, rubber, ceramic.

insulators

The net charge of a nonionized atom

is zero

It's important to know that no new charges are created during friction, induction, or contact. Although electrons move from one object to another the overall charge between the two objects is still zero. This is known as the _.

law of conservation of electric charge

How easy it is for electrons to move around depends on the _.

material

An electroscope has a metal ball at the top, a metal rod that goes through the middle, and _ on the bottom. They are all insulated from the surroundings with a rubber stopper at the top.

metal leaves

A positive ion has

more protons than electrons

An electroscope is charged positively, as shown by foil leaves that stand apart. As a negatively charged rod is brought close to the electroscope, the leaves

move closer together

The charge of an electron is

negative

One way we depict electric fields is by drawing electric field lines, which generally point towards _ charges and away from _ charges, and do not cross

negative, positive

If you comb your hair and the comb becomes positively charged, your hair becomes

negatively charged

To say that electric charge is conserved means that no case has ever been found where

net charge has been created or destroyed

Remember it is going to be the electrons and the protons in the atoms that make up the material itself. So, if we have a neutral object that means we are going to have an equal number of positive and negative charges. They are going to balance out, and there is going to be _.

no net charge

The common hydrogen atom consists of

one proton and one electron

Two charged particles held close to each other are released. As they move, the force on each particle increases. Therefore, the particles have

opposite signs

A rubbed balloon will stick to a wooden wall, which demonstrates charge

polarization

To understand electricity, you should start with an atom. Atoms contain charged particles - _ protons and _ electrons.

positive, negative

Two balloons that have been rubbed on your hair will strangely push each other away. This occurs because of the electric charge, which is displaced by the rubbing together of these materials. The hair becomes _ and the balloons become _, which is terminology developed by Benjamin Franklin.

positively charged, negatively charged

Atomic nuclei of almost all elements consist of

protons and neutrons

Opposite charges will attract one another, which is why your hair sticks to the balloon, and like charges repel, which is why the two balloons push each other away. This property of electric charge is carried by certain subatomic particles. The most common of these are _, which are positively charged, and _ which are negatively charged.

protons, electrons

Remember, the _ are going to stay where they are, it is always the _ that are moving.

protons, electrons

If a child went down the slide, friction of the hair on the slide actually _ and so now hair is _.

pulled electrons off, positively charge

Two charges are separated by a certain distance. If the magnitude of each charge is doubled, the force on each charge is

quadrupled

When the distance between two charges is halved, the electrical force between the charges

quadruples

Let's take two pieces of tape that are both stuck to a table. If you rip them both off the table and try to stick them together - they _ one another.

repel

Two like charges

repel each other

A difference between electrical forces and gravitational forces is that electrical forces include

repulsive interactions

A new movement sweeping across 18th century Europe was called the Enlightenment. Enlightened intellectuals used reason to question the world and their legacy was radical politics, iconoclastic art, and natural philosophy or _.

science

We could get the shock from a doorknob, or a balloon can stick to our hair, or we can be shocked by touching another person, or by a lightning strike. They're all governed by the same principle:_.

static electricity

To be safe in the unlikely case of a lightning strike, it is best to be inside a building framed with

steel

_ built a wooden frame from the top beam. He suspended two swings using silk rope. He also had a device like Francis Hauksbee's machine for generating static electricity. With a large audience in attendance, he got one of the orphan boys who lived at Charterhouse to lie across the two swings. He placed some gold leaf in front of the boy, he then generated electricity and charged the boy through a connecting rod. Gold leaf even feathers left to the boy's fingers. So, electricity could move from the machine to the boy's body, through his hands but the silk rope stopped it dead. It meant the mysterious electrical fluid could flow through some things but not through others.

stephen gray

As we bring a positively charged glass rod to the electroscope and if we touch the electroscope, now conduction takes place, we are actually transferring charges. As the rod is pulled away _.

the leaves are going to be held apart

As we bring a positively charged glass rod to the electroscope, there is induction going on, it will impact the charges within the electroscope. As the rod is pulled away - _.

the leaves go back to where they were

Conservation of charge means that

the total amount of charge in the universe is constant, no experimenter has ever seen a single charge destroyed by itself, electrons by themselves can be neither created nor destroyed, charges can neither be created or destroyed (all of the above)

In a good insulator, electrons are usually

tightly bound in place

All electrons are identical, all have exactly the same mass and charge.

true

All electrons are identical; all have exactly the same mass and charge.

true

Electricity is one of nature's most awesome phenomena and the most powerful manifestation of it we ever see is - lightning.

true

Just as a *gravitational field* is what allows the gravitational force to propagate, it is an electric field that allows the *electric force* to propagate.

true

Semiconductors can be made to conduct electricity and they can also be made to act like good insulators.

true

The study of electricity at rest is electrostatics.

true

The force F _ with the charge of two charged objects.

varies directly

The force F _ with the square of the distance between the centers of two charged objects.

varies inversely