Name: 
 

MCAS Electrical Charges and Forces



Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 1. 

Why does a plastic rod have a negative charge after being rubbed with a piece of fur? (MCAS 2006)
a.
The fur gives up protons to the rod.
c.
The fur gains protons from the rod.
b.
The rod gives up electrons to the air.
d.
The rod gains electrons from the fur.
 

 2. 

A negatively charged rubber rod was brought near some small pieces of  paper. The rod’s charges repelled the negative charges in the pieces. Which of the following caused the repulsion of the negative charges? (MCAS 2006)
a.
conduction
b.
gravitation
c.
induction
d.
insulation
 

 3. 

The figure below shows a neutral glass rod and a positively charged metal sphere. (MCAS 2006)
mc003-1.jpg
Which of the following best describes the movement of charges as this glass rod touches the sphere?
a.
Negative charges move from the sphere to the glass rod.
b.
Negative charges move from the glass rod to the sphere.
c.
Positive charges move from the sphere to the glass rod.
d.
Positive charges move from the glass rod to the sphere.
 

 4. 

Two oppositely charged objects are separated by a small distance. The objects are then moved three times farther apart from each other. Which of the following statements best describes what happens to the electrical force between the objects? (MCAS 2008)
a.
The force of attraction increases.
c.
The force of attraction becomes zero.
b.
The force of attraction decreases.
d.
The force of attraction stays the same.
 

 5. 

A teenager removes the plastic wrapping from a CD. The pieces of wrap cling to her hand.
Which of the following forces causes the wrap to cling to her hand? (MCAS 2008)
a.
electrostatic
b.
gravitational
c.
magnetic
d.
net
 

 6. 

The distance between two charges is represented by d. In which of the following diagrams is the attractive force between the two charges the greatest? (MCAS 2008)
a.
mc006-1.jpg
c.
mc006-3.jpg
b.
mc006-2.jpg
d.
mc006-4.jpg
 

 7. 

The diagram below shows two aluminum spheres. (MCAS 2004)
mc007-1.jpg
Aluminum sphere A contains a small negative charge and is touched by aluminum sphere B, which has a larger negative charge. Which of the following occurs next?
a.
Protons flow from sphere B to sphere A.
c.
Electrons flow from sphere B to sphere A.
b.
Protons flow from sphere A to sphere B.
d.
Electrons flow from sphere A to sphere B.
 

 8. 

Which of the following describes an object that must have a net negative charge? (MCAS 2005)
a.
It contains more molecules than atoms.
c.
It is carrying an electric current.
b.
It contains more electrons than protons.
d.
It is made of metal.
 

 9. 

A student combs her hair with a hard rubber comb and then hangs the comb on a loop of light thread that is suspended from a hook as shown below. (MCAS 2005)
mc009-1.jpg
She immediately combs her hair with a second identical comb and hangs it on the second suspended loop of light thread. If the combing has caused a charge to accumulate on the combs, which of the following shows what will occur?
a.
mc009-2.jpg
c.
mc009-4.jpg
b.
mc009-3.jpg
d.
mc009-5.jpg
 

 10. 

A balloon is rubbed against a sweater. Which of the following occurs because of the rubbing? (MCAS 2009)
a.
destruction of charged particles on the balloon
b.
release of charged particles from the air in the balloon
c.
movement of negatively charged particles from one material to the other
d.
movement of positively charged particles from one material to the other
 

 11. 

An electrostatic paint sprayer is used to spray paint evenly onto the surface of a car. Before the paint is sprayed, the car body is given a positive charge and the paint droplets are given a negative charge. The paint droplets experience an attractive force as soon as they are released from the sprayer. The paint droplets are originally sprayed at a distance of 30 cm from the car body, as shown below. (MCAS 2009)
mc011-1.jpg
Which of the following changes will cause the largest increase in the attractive force on the paint droplets?
a.
The charge on the car body is doubled.
b.
The charge on the paint droplets is doubled.
c.
The distance between the paint droplets and the car body is halved.
d.
The distance between the paint droplets and the car body is doubled.
 

 12. 

Which of the following conditions results in the buildup of static charge on an object? (MCAS 2010)
a.
when neutrons outnumber electrons
b.
when there are more protons than neutrons
c.
when there are more electrons than protons
d.
when all neutrons have been removed from the object
 

 13. 

A copper sphere, a glass sphere, a plastic sphere, and a rubber sphere are placed on individual insulating stands. A student touches each sphere with an electrically charged object.
The sphere made of which material will distribute the electric charge fastest over its entire surface area? (MCAS 2010)
a.
copper
b.
glass
c.
plastic
d.
rubber
 

 14. 

In a television set with a cathode ray tube display, a beam of negatively charged particles called cathode rays passes by a positively charged plate. The beam is deflected before it hits the television screen to produce an image. Which of the following changes would result in the greatest increase in the attraction between the negatively charged particles in the beam and the positively charged plate? (MCAS 2010)
a.
increasing distance between the plate and particles and increasing the charge on the plate
b.
increasing distance between the plate and particles and decreasing the charge on the plate
c.
decreasing distance between the plate and particles and increasing the charge on the plate
d.
decreasing distance between the plate and particles and decreasing the charge on the plate
 

 15. 

Which of the following statements describes the electric force between two oppositely charged particles as they approach each other? (MCAS 2011)
a.
The attractive electric force increases.
b.
The electric force becomes repulsive.
c.
The magnitude of the electric force decreases.
d.
The repulsive electric force becomes attractive.
 

 16. 

Electric charges can move most easily on which of the following objects? (MCAS 2011)
a.
glass tubes
b.
metal plates
c.
plastic cups
d.
rubber tires
 

 17. 

Which of the following actions would increase the electric force between two positively charged particles? (MCAS 2012)
a.
decreasing the mass of the particles
b.
decreasing the distance between the particles
c.
changing the charges from positive to negative
d.
transferring all the charge from one particle to the other
 

 18. 

A student rubs a glass rod with a piece of cloth and rubs a plastic ruler with a different piece of cloth. The glass rod becomes positively charged, and the ruler becomes negatively charged.
Which of the following statements describes the most likely result when the two pieces of cloth are brought close to each other? (MCAS 2012)
a.
The pieces of cloth repel each other.
b.
The pieces of cloth attract each other.
c.
A continuous current flows between the pieces of cloth.
d.
There is no electric interaction between the pieces of cloth.
 

 19. 

The diagram below shows the inside of a Van de Graaff generator.
mc019-1.jpg
A net charge can be built up on the generator’s sphere. A moving belt removes charged particles from the sphere and deposits them on the brush. Charged particles flow freely over the surface of the sphere, but do not move on the belt. The generator could be made from which of the following? (MCAS 2012)
a.
a copper belt and a plastic sphere
c.
a copper belt and an aluminum sphere
b.
a rubber belt and a plastic sphere
d.
a rubber belt and an aluminum sphere
 

 20. 

A neutral balloon is rubbed with a piece of wool cloth. As a result, the balloon has a negative static charge. Which of the following statements best explains why the balloon has a negative charge? (MCAS 2013)
a.
The balloon is a conductor.
b.
The balloon is an insulator.
c.
The balloon transfers charges to the cloth.
d.
The balloon receives charges from the cloth.
 

 21. 

Which of the following graphs best represents how the force between two identical electric charges varies as the charges move away from each other? (MCAS 2013)
a.
mc021-1.jpg
c.
mc021-3.jpg
b.
mc021-2.jpg
d.
mc021-4.jpg
 

 22. 

Two positively charged objects are separated by a large distance. One of the positively charged objects is replaced by a negatively charged object, and the two objects are moved closer to each other. Which of the following occurs in this situation? (MCAS 2013)
a.
The attractive force becomes a repulsive force, which increases as the objects move closer to each other.
b.
The repulsive force becomes an attractive force, which increases as the objects move closer to each other.
c.
The attractive force becomes a repulsive force, which decreases as the objects move closer to each other.
d.
The repulsive force becomes an attractive force, which decreases as the objects move closer to each other.
 

 23. 

What will happen when two objects with opposite electric charges are moved closer together? (MCAS 2014)
a.
The objects will attract each other with a greater force.
b.
The objects will attract each other with a smaller force.
c.
The objects will repel each other with a greater force.
d.
The objects will repel each other with a smaller force.
 

 24. 

Electrostatic air cleaners installed in hospitals use static electricity to reduce dust particles in the air. The neutral dust particles are attracted to positively charged ions sprayed into the air cleaners. (MCAS 2014)
mc024-1.jpg
Which of the following figures shows the charge distribution on the dust particle as it is attracted to the positively charged ions?
a.
mc024-2.jpg
c.
mc024-4.jpg
b.
mc024-3.jpg
d.
mc024-5.jpg
 

 25. 

Which of the following placements of two charges results in the greatest repulsive force? (MCAS 2014)
a.
mc025-1.jpg
c.
mc025-3.jpg
b.
mc025-2.jpg
d.
mc025-4.jpg
 

Open Response
 

 26. 

A student rubs a balloon on her hair and the balloon acquires a negative charge. (MCAS 2007)

a.       Explain why the balloon acquires a negative charge.

b.      After the balloon is rubbed on the student’s head, the student’s hair stands out from her head. Explain why this happens.

The student then brings the negatively charged balloon near another balloon that was charged in the same way.

c.       Describe and explain what happens when the negatively charged balloon is brought near another negatively charged balloon.
 

 27. 

In the diagram below, shaded circles 1, 2, and 3 represent fixed charged objects, and circle 4 represents a charged object that is free to move. The magnitude of all the charges is equal. (MCAS 2009)
es027-1.jpg
a.       Describe how charged objects 1, 2, and 3 will each affect object 4.
b.       Compare the magnitude of the electric force between object 3 and object 4 with the magnitude of the electric force between object 2 and object 4.
c.       Draw a diagram to show where object 4 will most likely move in relation to fixed objects 1, 2, and 3. Explain your answer.
 



 
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