Electricity and Magnetism

Which statement best describes a bar magnet that has been broken into two pieces?

• Both pieces have lost their magnetic poles.

• One piece has a north pole only, and the other piece has a south

  pole only.

• Each piece has both a north and a south pole.

• Both pieces have a north pole only.

A light bulb with a resistance of 100 ohms is plugged into a 120-volt outlet. What is the current flowing through the bulb?

• 0.83 ampere

• 1.2 amperes

• 20 amperes

• 220 amperes

Which statement is true about parallel circuits?

• They provide one path through which current can flow.

• They are usually called open circuits.

• They contain separate branches through which current can flow.

• They cease to function when one part of the circuit is disconnected.

Which best describes a circuit in series?

• Different parts are on separate branches.

• Current values are different at various points in the circuit.

• Electrons may take several paths.

• Electrons have only one path at all times.

A circuit has 2.25 amps of current and a resistance of 4.00 Ω. What is the voltage difference across the circuit?

• 9.00 V

• 6.25 V

• 1.78 V

• 0.56 V

A copper wire is connected across a constant voltage source. Which change will cause an increase in the current flowing through the wire?

• an increase in the length of the wire

• an increase in the resistance of the wire

• an increase in the diameter of the wire

• an increase in the insulation around the wire

Which will cause an electromagnetic solenoid to increase its strength?

• replacing the wire with an insulator inside the solenoid

• increasing the temperature surrounding the solenoid

• increasing the number of wire coils in the solenoid

• removing the iron core from the solenoid

How could the output voltage of an electrical generator be increased?

• by reducing the generator’s rotational speed

• by reducing the mechanical work put into the generator

• by increasing the resistance of the coils in the generator

• by increasing the number of coils in the generator’s electromagnet

Tags

NGSS.MS-ETS1-1

A student wants to build a simple circuit. Which material would be used to design a circuit with the least amount of resistance?

• long wires with a thin diameter

• long wires with a large diameter

• short wires with a thin diameter

• short wires with a large diameter

Which action will have the least effect on the strength of an electromagnet?

• changing the amount of current

• changing the current’s direction

• changing the number of wire loops

• changing the size of the metal core