Static Electricity

Question 1

What is electricity

Answer 1

Electricity is the flow of electrical charges - it is the result of the movement of electrons.
It is the main form of energy used today.

Question 2

NO NET CHARGE =

Answer 2

Matter with an equal number of protons and electrons.

Question 3

Some energy sources used to make electricity are:

Answer 3

hydro dams
solar
coal
natural gas
wind
nuclear energy

Question 4

Where does an electrical charge come from?

Answer 4

Each electron and each proton carries a tiny amount of electrical charge.

A net electrical charge comes from the imbalance of protons and electrons

Question 5

Positive (+)

Answer 5

a positive charge occurs when there are more protons than electrons.

Question 6

Negative (-)

Answer 6

a negative charge occurs when there are more electrons than protons.

Question 7

Nucleons

Answer 7

The particles in the nucleus of atoms, protons and neutrons, are called nucleons.

Nucleons are what give an atom its identity (6P = carbon, 19P = K ,etc).

Nucleons are BIG when compared to electrons.

When it comes to electricity, nucleons DO NOT move.

Question 8

Electrons

Answer 8

These particles are much smaller and lighter than nucleons

They are able to move from atom to atom in some materials.

They are responsible for the electrical phenomena we will be studying.

Question 9

Measuring electrical charges

Answer 9

In lab experiments and everyday life, we cannot really notice and measure the effect of a single electron’s charge; it is too small (certain experiments can).

It is more common to measure the charge of large groups of displaced electrons. One coulomb contains many MANY electrons!

Question 10

Charge of a proton

Answer 10

A proton has a positive charge of 1.60 x 10-19 C

Question 11

Charge of an electron

Answer 11

Electrons have a negative charge of - 1.60 x 10-19 C

Question 12

Unit

Answer 12

UNIT: coulomb ( C )

Question 13

How many electrons are in 1 Coulomb?
Remember, one electron has a charge of (negative) 1.60 x 10-19 C.

Answer 13

x = 6.25 x 10 18 electrons

Question 14

How much charge is contained in an object that has gained 3.2 x 1012 electrons?

Answer 14

Positive 3.52 x 10-5 C

Question 14

How much charge is contained in an object that has lost 500 000 000 electrons?

Answer 14

negative 1.15 x 10-10 C

Question 15

An object is found to have a net charge of -3.2 x 10-4 C. How many electrons were transferred IN or OUT of the object?

Answer 15

5.75 x 1018 electrons transferred OUT

Question 16

Electrical forces

Answer 16

When two charged objects come in close proximity to each other an electrical force is created.
If the objects are of opposite charge, the electrical force will pull them towards each other.
If the objects are of the same charge, the electrical force will push them apart.

Question 17

TWO TYPES OF ELECTRICITY

Answer 17

static and dynamic

Question 18

Static electricity

Answer 18

This is called static electricity because it is about stored, non-moving charges.

Question 19

CHARGING OBJECTS

Answer 19

Most object are neutral (# of e- = # of p+)

For an object to become charged a transfer of e- must take place.

An object is deemed ”charged” when it has an unequal amount of positive and negative charges.
Objects can be positively or negatively charged. It is always via gaining or losing valence electrons that an object becomes charged.

Question 20

FRICTION

Answer 20

Charging by rubbing (one material “likes” electrons more than another material and “takes” the electrons when they are rubbed)

Question 21

CONDUCTION

Answer 21

Charging by contact (excess/deficit of electrons is shared between the objects in contact)

Question 22

INDUCTION

Answer 22

Charging without contact (bringing a charged object close to another cause the uncharged object to become temporarily charged)

Question 23

Friction procedure

Answer 23

Start with: two neutral objects made of different materials
One “likes” electrons more, and will take them from the
other object (See table)
Finish with: two oppositely charged objects

Question 24

CHARGING BY CONTACT/CONDUCTION
procedure

Answer 24

Start with: one charged object, one neutral object
When the objects touch, the surplus (too many, negatively charged object) or lack (too few, positively charged object) of electrons is shared among the two objects
Finish with: two objects with same charge (each is less charged than the initial object: the initial charge is shared).

When conductive objects touch, as far as the electrons are concerned, the two objects essentially become one.
Excess (or lack of) electrons is spread out inside the new bigger object.
Each part of the object gets charged equally (depends on how conductive)
The initial charge is now shared among the 2 objects.
When you separate them, each retains the new excess/lack of electrons, which is less than the initial.

Question 25

CHARGING BY INDUCTION
procedure

Answer 25

Start with: one charged object, one neutral object
When the charged object is brought close to the neutral object, the electrons in the neutral object are either attracted or repelled by the charged object
The electrons in the neutral object become unevenly distributed, giving the appearance of opposite charges on each side of the neutral object
If you remove the charged object, the electrons in the neutral object redistribute themselves evenly over time

Question 26

Conductors and insulators

Answer 26

Most objects are neutral (# of e- = # of p+)
Charging an object = transferring e- from one object to another
Depending on how an object reacts to the transfer electrical charges,

Question 27

Conductors

Answer 27

Permits the free flow of electric charges
Ex: metals and electrolytic solutions

Question 28

Typical conductors

Answer 28

Silver
Gold
Copper
ALuminum
Mercury
Steel
Iron
Seawater
Concrete
Platinum
Brass
Bronze
Graphite

Question 29

Insulators

Answer 29

Impedes the free flow of electrical charges
The charges do not move well
Ex: Non metals (wood, plastic, glass, paper, ceramics …)

Question 30

3 groups

Answer 30

we classify them in 3 groups
Conductors
Semiconductors
insulators

Question 31

Semi conductors

Answer 31

Semiconductors
Used in electronics
Ex: Metalloids, carbon

Question 32

Typical insulators

Answer 32

Glass
Plastic
Ceramic
Rubber
Wood
Fabric
Paper
Wool
Cork

Question 33

ELECTRIC FIELD

Answer 33

A charged object has an influence on the space around it.
Faraday imagined this influence as invisible tentacles. Today we visualize the electric field as “lines” that radiate from charges.
The arrows always go from positive to negative.
(Electric field line arrows are drawn to show how an imaginary positive test-charge would move. Like charges repel, opposite charges attract.)

Question 34

Coulomb’s Law

Answer 34

Measures the electrical force between charges
Greater charge = greater the force
Greater distance between charge = weaker the force
No need to memorize the formula or the constant it is given. You do need to know the units for electrical force, charges, and distance

Question 35

Fe = kq1q2
r2

Answer 35

Fe = electrical force (N)
k = coulomb constant (9 x 109 Nm2/C2)
q1 and q2 = charge of particles (C)
r = distance between particles (m)

Question 36

ELECTRICAL FORCE

Answer 36

The electric force a charge experiences depends on it’s own charge (q1), the charge on the other object (q2), and the distance between the charged objects (r).
q1 and q2 are measured in Coulombs (C)
r is measured in meters (m)
k is a constant and has a value of 9x109 Nm2/C2