Electricity and Current REVIEW

The force or push that causes electric charges to move is called _______.

• resistance

• voltage difference

• current

• static electricity

Answer explanation

The force that causes electric charges to move is known as voltage difference. It represents the potential energy per unit charge, driving the flow of current in a circuit.

Electric charges always flow from _______ areas to _______ areas.

• positive, negative

• negative, positive

• positive, neutral

• neutral, negative

Answer explanation

Electric charges flow from areas of negative charge, where there is an excess of electrons, to areas of positive charge, where there is a deficit of electrons. Thus, the correct answer is negative, positive.

A material through which electrons do NOT flow easily is a(n) _______.

• insulator

• fuse

• conductor

• circuit breaker

Answer explanation

An insulator is a material that does not allow electrons to flow easily, making it the correct choice. In contrast, conductors allow easy flow of electrons, while fuses and circuit breakers are safety devices, not materials.

Mr. Robinson and his class are conducting an experiment. The class needs to choose a good insulator. Which of the following could be used as an insulator?

• plastic plate

• silver spoon

• copper wire

• gold necklace

Answer explanation

A plastic plate is a good insulator because it does not conduct electricity or heat well. In contrast, silver, copper, and gold are all metals that conduct electricity, making them poor choices for insulation.

Tags

NGSS.MS-PS3-3

Which of the following will increase the resistance of a wire?

• using a thicker/wider wire

• using a shorter wire

• increasing the temperature of the wire

• using silver instead of copper

Answer explanation

Increasing the temperature of a wire raises its resistance due to increased atomic vibrations, which impede electron flow. In contrast, thicker wires, shorter lengths, and using silver (which has lower resistance than copper) would decrease resistance.

What is the current produced by a 9-volt battery flowing through a resistance of 0.2 ohms?

• 1.8 amps

• 45 amps

• 0.022 amps

• 8.8 amps

Answer explanation

Using Ohm's Law (I = V/R), the current I is calculated as I = 9V / 0.2Ω = 45A. Therefore, the correct answer is 45 amps.

What does the symbol labeled #2 represent?

• light

• battery

• resistor

• switch

Answer explanation

The symbol labeled #2 represents a battery, which is commonly depicted in circuit diagrams. Batteries provide the necessary voltage and current to power the circuit, distinguishing them from other components like resistors or switches.

What process is the method by which a neutral object obtains an electrical charge from a distance?

• convection

• conduction

• radiation

• induction

Answer explanation

The process by which a neutral object obtains an electrical charge from a distance is called induction. This occurs when a charged object influences the distribution of charges in a neutral object without direct contact.

Which of the following objects would NOT be a good insulator of electric charge?

• skin

• wood

• plastic

• rubber

Answer explanation

Skin is a poor insulator of electric charge compared to wood, plastic, and rubber, which are effective insulators. This makes skin the correct choice for the object that would NOT be a good insulator.

Tags

NGSS.MS-PS2-3

Which symbol below would represent a device that can easily turn the circuit on or off?

• Symbol A

• Symbol B

• Symbol C

• Symbol D

Answer explanation

Symbol B represents a switch, which is commonly used to easily turn a circuit on or off. The other symbols do not indicate a simple on/off mechanism.