Charge & Magnetism Final 24-25 Review

Charge and Magnetism FInal Review

By Elias Heard

Atoms - the basic unit of matter

- protons (positive)

- neutrons (neutral)

- electrons (negative)

2.1 The Nature of Matter

Charged objects

• When an objects gains electrons, it becomes more negative

• When an object loses electrons, it becomes more positive

• If an object has the same amount of positive charges as negative charges, then it will be neutral

Multiple Choice

Will these particles attract or repel?

• attract

• repel

Multiple Choice

Will these particles attract or repel?

• attract

• repel

Multiple Choice

Which of the following can move from one atom to another?

• protons

• neutrons

• electrons

• the nucleus

Multiple Choice

Look at the following Triboelectric series. If I rub rabbit fur with a glass rod, what will happen to the charges?

• The negative charges will transfer from the fur to the rod, making the fur positive and the rod negative.

• The negative charges will transfer from the rod to the fur, making the fur negative and the rod positive.

• The positive charges will transfer from the fur to the rod, making the fur negative and the rod positve.

• The positive charges will transfer from the rod to the fur, making the fur positive and the rod negative.

Multiple Choice

Which of these materials will become more negative when I rub it with cotton?

• Wool

• Glass

• Paper

• Plastic

Multiple Choice

Why does static electricity make your hair stand on end?

• Similar charges on your hairs repel, causing them to stand away from each other

• Opposite charges on your hairs repel, causing them to stand away from each other

• Opposite charges on your hairs attract, causing the hair to stick together and up

• 
  Similar charges on your hairs attract, causing the hair to stick together and up

Conductors and Insulators

• Conductors: Materials that allow the flow of electric current.
• Insulators: Materials that do not allow the flow of electric current.
• Examples: Copper, aluminum, and silver are common conductors, while rubber, glass, and plastic are insulators.

Multiple Choice

glass, rubber, silk, and plastic are all examples of

• Conductors

• Insulator

• Thermel conductivity

• Materials

Multiple Choice

Metals such as copper, iron, gold, and silver are ...

• conductors
• brittle
• insulators
• resistors

Voltage

• The force motivating charge carriers to “flow” in a circuit is called voltage.

• Symbol used is V or E

• Unit of Measurement: Volts or V

Current

• Continuous movement of electric charge through the conductors of a circuit.

• Referred to in terms of “flow,” just like the flow of a liquid through a hollow pipe.

• Symbol used is I

• Unit of Measurement in Ampere (Amp) or A

Resistance

• Current tends to move through the conductors with some degree of friction, or opposition to motion

• Symbol is R

• Unit of Measurement is Ohm

• 
  

Additonal information about circuits

• Closed switch = on

• Open switch = off

• A fuse is a safety device that prevents short circuits
  

• Short circuits happen when the path of the wire is not connected properly

  (light does not turn on, can start fires)

Multiple Choice

How do we measure Voltage?

• Ω (Ohms)

• V (Volts)

• A (Amps)

• W (Watts)

Multiple Choice

What is the symbol used for Voltage?

• Ω

• A

• V

• C

Multiple Choice

What is the symbol used for Current?

• Ω

• A

• V

• I

Multiple Choice

How do we measure Current?

• Ω (Ohms)

• V (Volts)

• A (Amps)

• W (Watts)

Multiple Choice

What is the total resistance of the circuit?

• 100Ω

• 200Ω

• 25Ω

• 75Ω

Multiple Choice

How do we measure Resistance?

• Ω (Ohms)

• V (Volts)

• A (Amps)

• W (Watts)

Multiple Choice

What is the symbol used for Resistance?

• O

• R

• I

• V

Multiple Choice

What is the total resistance of a series circuit with values of 5, 9, and 17 ohms?

• 31

• 765

• 17

• 3

Multiple Choice

What is the current of a series circuit with values of 5, 9, 17 ohms, with a battery of 12V

• 0.3871

• 3870.0

• 372.0

• 4.4395

Multiple Choice

What is the Voltage of a circuit that has a resistance of 5 Ω and a current of 2 A?

• 25 V
• 10 V
• 2.5 V
• 0.4 V

Multiple Select

Which of these are short circuits?

• A

• B

• C

• All are short circuits!

​The number of bulbs and batteries impact the voltage and current in a series circuit.

The more batteries, the greater the voltage and the greater the current. The bulbs will be brighter.

But the more lightbulbs you add, the brightness of the bulbs will be less. This is because adding more bulbs adds more resistance. Which means the current will be less.

​Series Circuits

​More Bulbs

​More Batteries

Multiple Choice

Once the switch is flipped, which circuit will have the brighter bulb? Circuit A that has one bulb and one battery? Or Circuit B that has one bulb and two batteries?

• A

• B

Multiple Choice

Once the switch is flipped, which circuit will have the brighter bulbs?  Circuit C that has one bulb and one battery? Or Circuit B that has two bulbs and one battery?

• C

• D

​​The number of bulbs in a parallel circuit do not impact the brightness of the bulbs as long as they are on their own separate branch.


But the more bulbs there are on a single path, those bulbs will be dimmer than the bulb who has their own branch for the current to flow.

​Each bulb has it's own branch, and the same level of brightness.

One branch has two bulbs and they will be dimmer than the branch that has only one bulb.

Multiple Choice

Which of the two circuits would have the brightest bulbs? 

• A
• B

Multiple Choice

If all of the batteries have the same voltage, which circuit will have the dimmest (least bright) bulbs?

• LEFT

• MIDDLE

• RIGHT

• if they have the same voltage they will all be the same brightness.

Multiple Choice

In a Series circuit the more lightbulbs you add the brighter they get 

• False 
• True 

Multiple Choice

When you remove a bulb from a three bulb circuit, and the other two bulbs go off, then the bulbs must have been connected in __________.

• parallel
• series
• open
• closed

Multiple Choice

You remove any ONE of the light bulbs on one of the branches. What happens?

• The other bulbs will go out.
• The other bulbs will stay on
• The other bulbs will get dimmer.
• The battery will become stronger.

Magnetic Force & Strength

• You have probably played with magnets and might have noticed that two magnets exert forces on each other. Depending on which ends of the magnets are close together, the magnets either attract or repel each other. You might have noticed that the interaction between two magnets can be felt even before the magnets touch. The strength of the force between to magnets increases as magnets move closer together, and decreases as magnets move further apart.

• This is an inverse relationship

Opposite poles attract

Opposite poles on magnets attract one another. The north pole and south pole pull toward one another.

Same poles repel

The same poles repel one another. The north poles on both magnets push away from each other. The south poles on both magnets push away from each other.

Multiple Choice

When you hold two south pole ends of a magnet together are they going to attract (pull together) or repel (push apart)?

• repel (push apart)

• attract (pull together)

Multiple Choice

Will north and south poles attract or repel?

• attract (pull together)

• repel (push apart)

Multiple Choice

What happens if you cut a magnet in half?

• You would create a single stronger magnet on one side.

• Each half would become a magnet with its own north and south poles.

• The magnetic field would disappear.

• The domains would not be aligned and would scatter randomly.

Multiple Choice

What cause and effect relationship can you infer by looking at Table 1 below?

• The distance from the magnet makes no difference in the amount of force the magnet has.

• The farther the object is from the magnet, the stronger the force is.

• The closer the object is from the magnet, the stronger the force is.

Magnetic Domains

In magnetic materials such as iron, the magnetic field created by each atom exerts a force on other nearby atoms. These forces cause large groups of neighboring atoms to align, meaning that almost all north magnetic poles in the group point in the same direction. These groups of atoms with aligned magnetic poles are called MAGNETIC DOMAINS. Because the poles of individual atoms are aligned, the domain itself behaves like a large magnet.

Multiple Choice

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 an ordinary piece of metal, they're all jumbled up.

• In a magnet, the domains all point toward the north pole; in an ordinary piece of metal, they all point to the south pole.

• In a magnet, the domains are very strong; in an ordinary piece of metal, they're very weak.

• A magnet contains magnetic domains; an ordinary piece of metal does not.

Multiple Choice

Can magnetic domains travel within a material?

• Yes, they can move from one pole to anoter, causing an object to become magnetzied.

• No. Once an object's domains are unaligned, they can't be aligned.

• No. The domains rotate instead, causing an object to be magnetic or nonmagnetic.

• Impossible to tell.

Multiple Choice

What happens to iron filings as a magnet is waved above them?

• The iron filings separate in place, following the magnet as it is waved overhead.

• The iron filings stay in place, following the magnet as it is waved overhead.

• The iron filings rotate in place, following the magnet as it is waved overhead.

• The iron filings disappear in place, following the magnet as it is waved overhead.

Multiple Choice

Which of these images illustrates a unmagnetized material?