Physical Science - Module 12

Question 1

Who was the inventor of the electrical generator and the electrical transformer?

Answer 1

Michael Faraday

Question 2

What did Maxwell and Faraday work together on?

Answer 2

Maxwell put Faraday’s theories about electricity and magnetism on a firm mathematical foundation.

“Maxwell’s Equations”

Question 3

What are the three principles regarding the force that exists between electrical charges?

1. Key words - Attract/repel
2. Key words - force = size
3. Key words - force = distance

Answer 3

1. All electrical charge attract or repel one another: Like charges repel, while opposite charges attract.
2. The force between charged objects is directly proportional to the amount of electrical charge on each object.
3. The force between charged objects is inversely proportional to the square of the distance between the two objects.

Question 4

Photon

a s p o l t a l a p

Answer 4

A small “package” of light that acts like a particle.

Question 5

Charging by conduction

c a o b a i t c i c w a o t a h a e c

Answer 5

Charging an object by allowing it to come into contact with an object that already has an electrical charge.

Results in the same type of charge.

Question 6

Charging by induction

c a o w d c b t o a a c

Answer 6

Charging an object without direct contact between the object and a charge.

Results in the opposite type of charge.

Question 7

A black object is heated until it glows with with a nice, orange-yellow glow. If the black object has no net electrical charge, where does the light come from?

Answer 7

The light comes from the interaction of charged particles. Even though the black object has not net electrical charge, it is still composed of protons and electrons, which are each charged.

Thus, the light comes from the interactions between protons and electrons in the object.

Question 8

Two charged particles are placed 16 cm from each other and the resulting force is measured. The charge on object #1 is then halved and the charge on object #2 is divided by 4. The distance between the objects is also reduced to 4 cm. How does the new force compare to the old force?

Answer 8

Step 1: The force is directly proportional to the charge of each object. #1 is divided by 2; #2 is divided by 4. When the force is divided by 2 and then 4, the total division is 8.

Step 2: The force is inversely proportional to the square of the distance between the charges. The distance went from 16 to 4 = divided by 4. When the distance is divided by 4, the force is multiplied by 4 squared = 16.

Step 1 gave us a division of 8 and Step 2 gave us a multiple of 16 = 16/8 = 2 times stronger than the old force.

Question 9

If you want to give an object a positive charge, but the only source of charge you have is negative, would you charge the object by conduction or induction?

Answer 9

Charge by induction.

Charging by induction gives you the charge opposite to what you are using.

Question 10

Electrical Current

t a o c t t p a f p i a e c e s

Answer 10

The amount of charge that travels past a fixed point in an electric circuit each second.

Question 11

What is an Ampere?

Answer 11

The unit of measure of an electrical current.

Question 12

What is the abbreviation for “Ampere”?

Answer 12

amp or A

Question 13

Conventional Current

c t f f t p s o t b t t n s. t i t w c i d i c d, e t i i w

Answer 13

Current that flows from the positive side of the battery to the negative side. This is the way current is drawn in circuit diagrams, even though it is wrong.

Question 14

Does the longer line represent the positive or negative side of the battery?

Answer 14

Positive

Question 15

Electricity is the flow of __________.

Answer 15

Electrons

Question 16

Which way does electricity flow?

Answer 16

Electricity flows from the negative side of the battery (the source of the electrons) to the positive side of the battery (where the electrons go).

Question 17

Resistance

t a o a m t i t f o c

Answer 17

The ability of a material to impede the flow of charge.

Question 18

What can resistance produce?

Answer 18

Heat and light.

Question 19

What happens to the electrons in an electrical circuit?

Answer 19

As they travel through the metal, the collisions they experience convert the energy produced by the electromagnetic force into heat or light.

Question 20

Open Circuit

a c t d n h a c c b t t s o t p s. a a r c d n f.

Answer 20

A circuit that does not have a complete connection between the two sides of the power source. As a result, current does not flow.

Question 21

In order for electricity to flow, it must have a ___________ circuit.

Answer 21

complete

Question 22

What is the difference between a parallel circuit and a series circuit?

Answer 22

Devises in a series circuit are in a line and the electricity can only flow if all devices are working.

A parallel circuit allows devises to work independently of one another because there are two or more paths for the electricity to flow.

Question 23

How do magnetic poles attract and repel?

Answer 23

Like poles repel one another; opposite poles attract one another.

Question 24

What are the names of the poles of a magnet?

Answer 24

North and South

Question 25

What word is used to describe a magnet with two poles?

Answer 25

Dipoles - because magnetic poles always come in pairs: one north and one south.

Question 26

What are magnetic field lines?

Answer 26

The way the force between the poles of a magnet is illustrated.

Question 27

How is the strength of magnetism measured?

Answer 27

The strength of a magnet depends upon what percentage of the atoms in the material are aligned. The larger the percentage, the stronger the pole of a magnet.

Question 28

Which way does magnetic force flow? From N to S or from S to N.

Answer 28

From North to South.

Question 29

Draw the force exerted by a + (positive) object and the force exerted by a - (negative) object.

-                                                         +

Answer 29

• —————-> <___________ +

Question 30

When drawing pictures of electrical current, which way do you draw the flow? From + to - or from - to +.

Answer 30

From + to - (this is the conventional drawing)

Question 31

If the force of the two north poles of two different magnets are measured and then distance between the two poles is doubled, what is the resulting magnetic force?

Answer 31

The force is decreased by a factor of 4. The force varies inversely with the square of the change of the distance.

Question 32

If a positively charged rod is charging another rod to result in a negatively charged rod, is induction or conduction used to charge the rod?

Answer 32

It was charged by induction because the charge resulted in the opposite type of charge.

Question 33

How can you get high energy out of a low voltage circuit?

Answer 33

Low voltage means that each electron will have only a little bit of energy, but you can get a lot of energy out of the circuit if you put a lot of energy in the circuit.

Question 34

How does conventional current flow differ from the actual flow of electrons?

Answer 34

Conventional current flow is drawn from + to -, but actual electron flow is from - to +.

Question 35

If you have a string of lights where if one light goes out, the rest go out, too, how is it wired?

Answer 35

It’s a series circuit.

Question 36

If you have a chandelier where if one light goes out, the rest will stay on, how is it wired?

Answer 36

It’s a parallel circuit.

Question 37

You have two wires of the same length and have the same current running through them, but one wire is thicker than the other. In addition, one wire is hotter than the other. Which one is hotter - the thin or the thick wire - and why?

Answer 37

The thinner wire is hotter.
The wire with the higher resistance is hotter.
A thicker wire will have a lower resistance because its electrons will spread out over a greater distance and not get as hot as a thinner wire.

Question 38

What causes objects to be magnets?

Answer 38

The atoms in the object are aligned. Some objects can become magnetized, some cannot.

Question 39

What happens if you cut a magnet in half?

Answer 39

You will end up with two magnets, both with a North and South pole. Therefore you will have two North poles and two South poles.