Physics Test 7

(a) Why are metals good conductors? (b) Why are materials such as rubber and glass good insulators?

(a) Free Electrons (b) Bound Electrons

(a) If electrons are rubbed from cat's fur onto a rubber rod, does the rod become positively or negatively charged? (b) How about the cat's fur?

(a) negatively (b) positively

In one part of the room, there are two balloons - one hanging straight down and the other being attracted to it. This evidence that ____________________________________________________________.

... nonsense! This would never happen if the balloons are identical and simply suspended by strings. They will attract each other and both be deflected from a vertical orientation.

What happens to the charges in your hair and a balloon if you rub them together? (Check all that apply.) - Your hair will become neutral. - The balloon will become positively charged. - Your hair will become negatively charged. - The balloon will become neutral. - The balloon will become negatively charged. - Your hair will become positively charged. What is this called? - This is called charging by contact. - This is called neutralization by contact. - This is called neutralization by friction. - This is called charging by friction.

1) - The balloon will become negatively charged. - Your hair will become positively charged. 2) This is called charging by friction.

A negatively charged object has more __________________ than __________________.

1) Electron 2) Proton

When you rub a glass rod with a silk cloth, electrons are transferred from the __________________ (glass, silk) to the __________________ (glass, silk). As a result, the glass rod acquires a __________________ (+ or -) charge and the silk cloth acquires a __________________ (+ or -) charge. (Hint: Celluloid (-) Sulfur Rubber Copper, Brass Amber Wood Cotton Human Skin Silk Cat Fur Wool Glass Rabbit Fur (+)

1) Glass 2) Silk 3) Positive 4) Negative

Triboelectric series

1) It is a listing of a variety of materials in order of their relative attraction for the electrons of another material. 2) Materials listed near the top of the table have a higher affinity for electrons than those located below them. 3) When two materials are rubbed together, electrons are transferred from the material that has the lesser affinity for the E to the material that has the greater affinity to E. 4) The object that gains the E acquires a negative charge and the object that loses E acquires a positive charge.

Voltage

1) It is the difference in the amount of energy carried by current at two points in a circuit. 2) Potential energy in a circuit 3) It is electric potential energy per unit charge, measured in joules per coulomb.

Resistance

1) It is the measure of how strongly a material resists current. 2) It is the OPPOSITION to CURRENT 3) Certain materials resists more than others

Current

1) It is what flows and carries power in a circuit. 2) It is the movement of electrical charges (electrons) through the use of ENERGY difference (VOLTAGE) between two points. 3) It is the amount of charge that passes a point in a given time interval. 4) It is a flow of electrical charge carriers, usually electrons or electron-deficient atoms.

Suppose you rub a glass rod with a silk cloth and a second glass rod with rabbit fur. The silk cloth will acquire a __________________ (+ or -) charge; the rabbit fur will acquire a __________________ (+ or -) charge. The rabbit fur and the silk cloth will then be observed to __________________ (attract, repel, not interact with) each other. (Hint: Celluloid (-) Sulfur Rubber Copper, Brass Amber Wood Cotton Human Skin Silk Cat Fur Wool Glass Rabbit Fur (+)

1) Negative 2) Positive 3) Attract

When two materials are rubbed together, electrons are transferred from the material that has the greater affinity for electrons. The object that gains the electrons acquires a __________________ (+ or -) charge __________________ (+ or -).

1) Negative 2) Positive

Suppose you rub a rubber rod with a silk cloth and a second rubber rod with a wool sweater. The silk cloth will acquire a __________________ (+ or -) charge; the wool sweater will acquire a __________________ (+ or -) charge. The sweater and the cloth will then be observed to __________________ (attract, repel, not interact with) each other. (Hint: Celluloid (-) Sulfur Rubber Copper, Brass Amber Wood Cotton Human Skin Silk Cat Fur Wool Glass Rabbit Fur (+)

1) Positive 2) Positive 3) Repel

An an object begins to gain or lose electrons from its atoms, it becomes __________________ or __________________ charged.

1) Positively 2) Negatively

Protons are __________________ charged, and electrons are __________________ charged.

1) Positively 2) Negatively

A positively charged object has more __________________ than __________________.

1) Proton 2) Electron

The __________________ are positively charged and the __________________ are negatively charged

1) Protons 2) Electrons

The charged parts of an atom are the __________________ and the __________________.

1) Protons 2) Electrons

Like charges __________________, and opposite charges __________________.

1) Repel 2) Attract

When you pull a cotton sweater off your skin, electrons are transferred from the __________________ (cotton, skin) to the __________________ (cotton, skin). As a result, your body acquires a __________________ (+ or -) charge and the cotton sweater acquires a __________________ (+ or -) charge. (Hint: Celluloid (-) Sulfur Rubber Copper, Brass Amber Wood Cotton Human Skin Silk Cat Fur Wool Glass Rabbit Fur (+)

1) Skin 2) Cotton 3) Positive 4) Negative

According to Ohm's law, the current in a circuit increases if the __________________ increases. The current decreases if the __________________ increases.

1) Voltage 2) Resistance

Distinguish between a series circuit and a parallel circuit.

A series circuit has one path that electrons can go one while a parallel circuit has two paths that the electrons can go on.

The unit for current is the __________________

Ampere

What does it mean to say an object is electrically neutral?

An object is electrically neutral when its net charge is zero.

Your physics teacher has prepared the room for the class's entry by suspending several inflated balloons from the ceiling. Upon entering the physics room, you observe two balloons being drawn towards each other. The attraction of these balloons for one another provides evidence that ________________________________________________________________________.

At least one of the balloons is charged; the other is either charged or neutral.

A charged object and a neutral object will __________________.

Attract.

A __________________ provides voltage to a circuit.

Battery

Why are protons and neutrons unable to leave the atom?

Because they are tightly bound.

As you look around the room, you observe two other balloons being pushed away from each other. The repulsion of these balloons from one another provides evidence that ________________________________________________________________________.

Both balloons are charged with the same type of charge.

A __________________ has a complete path for the current and contains no breaks.

Closed Circuit

The unit in which charge is measured is the __________________

Coulomb

What is the SI unit of charge?

Coulomb

__________________ is what flows and carries power in a circuit.

Current

What does the "J" stand for in a equation: J = I/A

Current Density

How much does each battery cost?: D Batteries C Batteries AA Batteries AAA Batteries 9V Batteries

D Batteries: 1.5 C Batteries: 1.5 AA Batteries: 1.5 AAA Batteries: 1.5 9V Batteries: 9V

__________________ are used when drawing circuit diagrams.

Electrical symbols

An object is __________________ when it has equal numbers of positive and negative charges.

Electrically Neutral

On the other hand, __________________ are located outside the nucleus and are easily removed from or added to atoms.

Electrons

What's the formula for Coulombs law?

Force = q1(Charge),q2 (Charge) ------------------------------- Distance^2

An electrically neutral atom is an atom which ____________________________________.

Has a balance of protons and electron (the same number of each)

An electrically charged atom (sometime referred to as an ion) can be distinguished from an electrically neutral atom in that the charged atom (ion) ____________________________________.

Has an imbalance of protons and electrons (unequal numbers of these)

What's the formula for Current?

I(Current) = Q(Charge) --------------- T(Time) Or V(Voltage) ------------- R(Resistance)

What's the formula for Ohm's Law?

I(Current) = V(Voltage) --------------- R(Resistance) Or V(Voltage) = I(Current) x R(Resistance)

What does it mean to say that current and resistance in a circuit are inversely proportional?

If the resistance is multiplied by a number, the current is divided by that number.

What does it mean to say that current and voltage in a circuit are directly proportional?

If the voltage is multiplied by a number, the current is multiplied by that number.

Ohm's law

It explains the relationship between current, voltage, and resistance in a circuit.

Open Circuit

It has a break it, so there is no current.

Closed Circuit

It has a complete path for the current and contains no breaks.

Conductor

It is a material that ALLOWS CURRENT to flow through it to do electrical work.

Insulator

It is a material that DOES NOT ALLOW all CURRENT to flow through it to do electrical work.

Superconductor

It is a material that can conduct electricity or transport electrons from one atom to another with no resistance.

Ohm

It is the unit for measuring resistance.

Volt

It is the unit for measuring voltage.

Switch

It is used to create a break in a circuit.

Electrically Neutral

It is when an object has equal numbers of positive and negative charges.

What is an electric dipole?

It is when you have two objects that are charged, that have opposite but equal electric charges, that are unconnected by distance.

What is the function of a fuse or a circuit breaker in a circuit?

It prohibits currents from becoming too great and overheating.

What is lightning?

Lightning is a giant spark of electricity that is caused by water and ice that's in the cloud. The water is within warm air, while the ice is within cold air. Throughout the storm the water and the ice hit each other, and then separate while in the air. As they hit each other, they make "static electrical charges" within the clouds. Due to the bumping each other, some charges were either positive or negative. Due to this, the positive charges ended up on top of the cloud while the negative charges ended up on the bottom. When the negative charge gets enough power, the cloud lets out an energy. The energy then goes to a place that has an opposite charge than itself. The lightning can either go from the cloud to the ground or the cloud to another cloud.

What is a Conductor made out of?

Metals

What is the overall charge in an atom?

Neutral

The __________________ are not charged.

Neutrons

Are all the electrons flowing in a circuit provided by the battery? Explain.

No, because the battery is pushing the electrons in the circuit, but the electrons were already there.

What is a Insulator made out of?

Non-metals

The __________________ is the unit for measuring resistance.

Ohm

What is the unit for resistance?

Ohm

__________________ explains the relationship between current, voltage, and resistance in a circuit.

Ohm's law

A __________________ has a break it, so there is no current.

Open Circuit

What's the formula for Power?

P(Power) = V(Voltage) x I(Current) or P(Power) = E(Work) -------------- t(Time)

Is an objects net charge positive or negative if it loses electrons?

Positive

Another word for Voltage is:

Potential difference

Which has more mass -- a proton or an electron?

Proton

The __________________ reside in the nucleus of atoms and are tightly bound; they will never leave an atom as a result of electrostatic procedures.

Protons

Battery

Provides voltage to a circuit.

What's the formula for Resistance?

R(Resistance) = V(Voltage) ----------------- I(Current)

__________________ is the measure of how strongly a material resists current.

Resistance

Is the electric current: Scalar or Vector?

Scalar but the arrows are often drawn to indicate the direction of the current flow.

A __________________ is used to create a break in a circuit.

Switch

Electric Force

The attractive or repulsive interaction between any two charged objects.

How does the charge of an electron compare to the charge of a proton?

The charge of an electron is equal to the charge of a proton with the opposite sign.

During a physics lab, a plastic strip was rubbed with cotton and became positively charged. The correct explanation for why the plastic strip becomes positively charged is that ________________________________________________________________________

The plastic strip lost electrons to the cotton during the charging process.

Why are household appliances almost never connected in series?

The reason why household appliances almost never connected in series is because if one appliance went out then all the other appliances would go out.

What is meant by a short circuit?

The short circuit bypasses the "regular" circuit, meaning that it's the shorter path.

Ampere

The unit for current

Coulomb

The unit in which charge is measured in.

How are electrons able to leave the atom?

They are exposed to other atoms and to forces that are capable of ejecting them or stripping them of the atom.

Where are protons and neutrons located?

They are located in the interior of an atom (the nucleus).

Where are electrons located?

They are located on the exterior of an atom (ELECTRON CLOUD).

Atom

They are the building blocks of matter.

Electrical symbols

They are used when drawing circuit diagrams.

How do protons and electrons differ in their electric charge?

They differ because protons are positive and electrons are negative. They also differ because you can gain or lose electrons but you can't gain nor lose protons.

What's the formula for Voltage?

V(Voltage) = E(Work) . --------------- . q(Charge) Or V(Voltage) = I(Current) x R(Resistance)

The __________________ is the unit for measuring voltage.

Volt

__________________ is the difference in the amount of energy carried by current at two points in a circuit.

Voltage

Current in a conductor is equal to the __________________________________

Voltage applied to it divided by it's resistance.

Why is it important to always have dry hands when working with circuits?

Water can make skin conductive.

Are Coulombs worth more or less than electrons?

Worth more AKA it's worth a billion.

Explain what must happen in order for an oxygen atom to become negatively charged.

You must add electrons.

Explain what must happen in order for an oxygen atom to become positively charged.

You must take away electrons.

The greater the resistance in a circuit, the less the __________________.

current

What symbol is used to represent this ohm?

Ω