Electrostatics Review

Which type of charge follows the path of the electric field?

• Positive

• Negative

• Neutral

Answer explanation

Electric fields start at positive charges and move towards negative charges.

Why do clothes sometimes stick together after being in the dryer?

• Because of the heat

• Because of the weight of the clothes

• Because of static electricity

• Because of the moisture

Answer explanation

The clothes are made up of different materials. When two pieces of clothes rub together they exchange electrons, causing the clothes to become oppositely charged.

Which of the following is NOT a property of static electricity?

• 
  It involves the transfer of electrons.

• 
  It can only occur in metals.

• 
  It can cause objects to attract or repel each other.

• 
  It can be generated by rubbing certain materials together.

Answer explanation

Static electricity can occur in any material (plastics, organic material, rubber, etc.) the material only determines the exchange of the electrons and which material will gain or lose electrons. Some materials exchange electrons better than others.

The process of rearranging electrons on a neutral object by bringing a charged object close to it is called

• Charging by conduction

• Charging by induction

• Charging by radiation

• Charging by convection

Answer explanation

Charging by induction is achieved by bringing a charged object near but not touching a neutral object.

How do storm clouds become charged to produce lightning?

• Friction from water particles rubbing together due to high winds in clouds.

• Induction from clouds forming near each other.

• Conduction because water is a good conductor.

• Magic

Answer explanation

When storm clouds form, high winds cause the water droplets and other particles to swirl around each other. As the water droplets and particles rub against each other, they transfer electrons. Eventually, the positively charged particles move to the top of the storm cloud and negative particles move to the bottom of the cloud.

A proton and an electron are placed in between two oppositely charged plates. The plates produce a uniform electric field. The electrostatic force on the proton

• Is greater than the electrostatic force on the electron becuase it has a greater mass.

• Is less than the electrostatic force on the electron becuase it has a smaller mass.

• Is equal to the electrostatic force on the electron becuase they have he same mass.

• Is equal to the electrostatic force on the electron becuase they have the same charge.

In order for a charged particle to be suspended motionless within an electric field produced by the two parallel plates

• The electrostatic force on the particle must be opposite in direction and less than the gravitational force on the particle

• The electrostatic force on the particle must be zero

• The electrostatic force on the particle must be equal in direction and magnitude to the gravitational force on the particle

• The electrostatic force on the particle must be opposite in direction and equal in magnitude to the gravitational force on the particle

Answer explanation

In order for a particle to remain motionless, its net force must be zero. The electrostatic force be opposite in direction and equal in magnitude in order to cancel out the gravitational force.

Which of the following best describes electric field lines?

• They originate from positive charges and end on negative charges

• They indicate the path that a positive test charge would follow

• Both A and B

• Neither A nor B

Answer explanation

Electric fields always flow from positive charges to negative charges. Positive charges will move along electric field lines while negative charges will move against field lines.

An ebonite rod is rubbed with rabbit's fur. During this process, a negative charge is given to the ebonite rod by

• Adding electrons to the rod

• Removing protons from the rod

• Adding protons to the rod

• Removing electrons from the rod

Answer explanation

Only electrons can be transfer between objects. If an object aquires a negative charge, it aquires an excess of electrons.

When a negatively charged rod is brought near the knob of a neutral electroscope the leaves of the electroscope repel each other. This is becuase

• The electrons move away from the leaves into the knob, giving the leaves a positive charge

• The electrons move away from the knob into the leaves, giving the leaves a negative charge

• The protons move away from the knob into the leaves, giving the leaves a positive charge

• The protons move away from the leaves into the knob, giving the leaves a negative charge

Answer explanation

Electrons will be repelled by the negatively chraged rod. The farthest they can move is into the leaves, giving the leaves negative charges which repel.