DC - Unit 3 Practice Test

The precipitator uses a high-voltage DC power supply to provide a set of wires with a positive charge and a set of plates with a _____ charge. a. positive b. negative

negative

Bringing a charged test object near the ball of a charged electroscope causes the leaves to move closer together. This indicates that the test object charge is the _____ polarity as the electroscope charge. a. opposite b. same

opposite

When an object protected by a lightning _____ is struck by a lightning bolt, it will bleed the lightning discharge to ground before the protected object can be harmed. a. rod b. arrestor c. umbrella d. catcher

rod

The static charge sometimes used during spray painting is called a(n) _____ static charge. a. useful b. nuisance

useful

Insulators are the only materials that can hold _____ stationary. a. electrons b. atoms

electrons

The semiconductor material used as a coating on copy machine drums is _____. a. silicon b. germanium c. aluminum d. selenium

selenium

Selenium is a(n) _____. a. semiconductor b. conductor c. insulator

semiconductor

A precipitator is a type of _____. a. power supply b. small wire c. air filter d. lightning rod

air filter

The lightning protection device that does not connect directly to the object to be protected is called the lightning _____. a. umbrella b. rod c. arrestor d. catcher

arrestor

The current flow that occurs within a lightning bolt flows _____. a. from positive to negative b. in both directions c. from negative to positive

from negative to positive

If a thundercloud has a positive charge, the current in the lightning bolt will flow from the _____. a. ground to the cloud b. cloud to the ground

ground to cloud

Electrostatic charges occur on _____. a. conductors b. insulators

insulators

A static electric charge is an electric charge which _____ moving. a. is not b. is

is not

If you walk across a carpet, touch a doorknob and get a shock, the shock was the result of a(n) _____ static charge. a. useful b. nuisance

nuisance

The static charge that accumulates on clothes in a dryer is a(n) _____ charge. a. nuisance b. useful

nuisance