Physics Study Guide CH: 18 Electrical Charge

What is an electric field?

An electric field is an area where the electrical forces act on a charged object.

A positively charged balloon is brought near a neutral conducting sphere as shown below. While the balloon is near, the sphere is touched (grounded). At this point, there is a movement of electrons. The electrons move _____________. a. into the sphere from the ground (hand) b. out of the sphere into the ground (hand) c. into the sphere from the balloon d. out of the sphere into the balloon e. from the ground through the sphere to the balloon f. from the balloon through the sphere to the ground g. .... nonsense! Electrons do not move at all. Notice: the letters in the picture don't apply.

Answer: A. into the sphere from the ground(hand)

What is the unit for charge?

Coulomb or C

TRUE or FALSE: An object that becomes grounded gains neutrons during the grounding process.

False

Which one of these sources of charge is positively charged and which is negatively charged. Explain your answer. (Image is on the Physics Study Guide)

The one on the left is negative because the vectors are pointed toward the charge. The one on the right is positively charged because the vectors are pointed away.

Which set of charged objects has the stronger electric field intensity? Explain your answer. (Image on Physics Study Guide)

The one on the right because it has a higher density of electric field lines.

In physics and electrical charges world, what does the term ground mean?

A ground has a infinite supply of electrons and is useful for balancing out the charge of any charged object to make it neutral.

In charged objects, which subatomic particle is actually moving from object to object.

Electrons. Protons and Neutrons are fixed to the nucleus and cannot move freely.

What is electrostatic equilibrium?

Electrostatic equilibrium is what is reached when the charges are balanced out and no longer move (meaning that they are not moving toward or away from each other).

A 0.90-gram balloon with a charge of -75 nC is located a distance of 12 cm above a plastic golf tube that has a charge of -83 nC. Find the net force and acceleration of this system.

Force is 0.00389 N Acceleration is 4.32 m/s^2

What are the 3 different ways an object can become charged? How do they differ from one another?

Friction - in contact and surfaces are being rubbed together. Objects started out as being neutral and gain charge due to electron affinity Induction - a charged object is brought near a non charged object but does not touch it. Conduction - a charged object is touched to a non charged object and electrons are transferred.

And why is grounding important?

Grounding is important because it neutralizes charged which could have been dangerous in different situations.

A negatively charged balloon is brought near a neutral conducting sphere as shown below. As it approaches, charge within the sphere will distribute itself in a very specific manner. Which one of the diagrams below properly depicts the distribution of charge in the sphere?

Image C. The balloon does not touch the sphere meaning that the sphere remains neutral, but the electrons will be repelled to the other side of the sphere.

Which of the diagrams below best represents the charge distribution on a metal sphere when a positively charged plastic tube is placed nearby? (sorry couldn't copy the images from Google Doc)

Image D since the positive charges are attracted to the negative charges.

Is electrical force a contact force?

It is a long distance force.

Is electrical force a vector?

It is a vector

What happens when a charged object comes into contact with a neutral object?

It is attracted to it since the electrons will move allowing for it to be attracted.

What is electrical force measured in?

It is measured in Newtons, like all forces.

What does it mean for an object to be polarized?

It means there is a positive charge on one side of the object and a negative charge found on the other side.

What do each of the variables in Coulomb's Law equation stand for?

K = a constant equal to 9x10^9 in air. It is a measure of air conductivity Q = the charges of two objects F = the electrical force between two objects D = the distances between the center of mass of two charged objects

What is the charge of a single electron?

Negative 1.6 x 10^-19 C

Determine the quantity and type of charge on an object that has 3.62 x 10 ^12 more protons than electrons.

Positive because there are more protons. Multiply the number of protons by the charge of one proton and the answer is 5.8 x 10^-7 C.

8.25749 x 10^17 protons and 5.26 x 10^14 electrons; the charge on this object is _______Coulombs.

Positive because there are more protons. Subtract the number of electrons from the protons, then multiply by the charge of one proton. The answer is 0.13 C.

If the electrons move from the sweater to the balloon, which has the greater electron affinity? How can you tell?

The balloon does. Electron affinity means that the object attracts electrons to itself so if the balloon gains a negative charge, that means the electrons traveled from the sweater to the balloon because it has a higher affinity for the electrons.

What's the difference between a conductor and an insulator?

The electrons found in a conductive material are more free to move around than those found in a insulative material.

Define electrical force.

The force experienced by a charged object. This force can either attract or repel and depends on the charges involved.

A neutral metal sphere is touched by a negatively charged metal rod. As a result, the sphere will be ____ and the metal rod will be ____. Select the two answers in their respective order. a. positively charged b. negatively charged c. neutral d. much more massive e. ... not enough information to tell

The sphere will be ___B: negatively charged___ and the metal rod will be __B: negatively charged___.

Determine the electrical force of attraction between two balloons with separate charges of +3.5 x 10-8 C and -2.9 x 10-8 C when separated a distance of 0.65 m.

There is an attractive force of 2.16x10^-5 N

Where would you expect an electrical field vector to have the greatest strength?

When it is closer to the charged object

A metal sphere is electrically neutral. It is touched by a positively charged metal rod. As a result, the metal sphere becomes charged positively. Which of the following occur during the process? List all that apply. a. The metal sphere gains some protons. b. Electrons are transferred from the sphere to the rod. c. The metal sphere loses electrons. d. The overall charge of the system is conserved. e. Protons are transferred from the rod to the sphere. f. Positive electrons are moved between the two objects.

b. Electrons are transferred from the sphere to the rod. c. The metal sphere loses electrons. d. The overall charge of the system is conserved.

Which statement best explains why a rubber rod becomes negatively charged when rubbed with fur? a. The rubber that the rod is made of is a better insulator than fur. b. The fur is a better insulator than the rubber. c. Molecules in the rubber rod have a stronger attraction for electrons than the molecules in the fur. d. Molecules in the fur have a stronger attraction for electrons than the molecules in the rubber rod.

c. Molecules in the rubber rod have a stronger attraction for electrons than the molecules in the fur.