Ch 20 Electricity

The strength of an electric field depends on the

• amount of charge that produced the field.

• distance from the charge.

• tha amperes

• both A and B

What is the SI unit of electric charge?

• ampere

• ohm

• volt

• coulomb

If a neutral metal comb is held near an object with a negative charge, the comb will become charged by

• induction.

• contact.

• friction.

• static discharge.

. The type of current in your school is mostly

• direct current.

• alternating current.

• series current.

• produced by batteries.

An electrical insulator has

• electrons that freely move

• more protons than electrons.

• negatively charged ions.

• electrons tightly bound to its atoms.

Which of the following would reduce the resistance of a metal wire?

• increasing its thickness

• increasing its temperature

• increasing its length

• all of the above

 $V=IR$  The current in a clothes iron measures 5.0 amps. The resistance of the iron is 24 ohms. What is the voltage?

• 120 V

• 4.8 V

• 19 V

• 600 V

How many paths through which charge can flow would be shown in a circuit diagram of a series circuit?

• one

• two

• none

• an unlimited number

If you know the power rating of an appliance and the voltage of the line it is attached to, you can calculate the current the appliance uses by

• multiplying the voltage by the power.

• subtracting the power from the voltage.

• dividing the voltage by the power.

• dividing the power by the voltage.

Which of the following is made from a crystalline solid that conducts a current only under certain circumstances?

• cathode-ray tube

• analog devise

• semiconductor

• vacuum tube