Understanding Electric Forces and Fields

How do electric charges interact with each other?

• They always attract each other.

• They always repel each other.

• Like charges repel, unlike charges attract.

• Like charges attract, unlike charges repel.

Answer explanation

Electric charges interact based on their types: like charges (positive-positive or negative-negative) repel each other, while unlike charges (positive-negative) attract each other. Thus, the correct choice is: Like charges repel, unlike charges attract.

Tags

NGSS.MS-PS2-3

What determines the strength of an electric field?

• The color of the charged object.

• The amount of charge and the distance from the charge.

• The temperature of the environment.

• The speed of the charged object.

Answer explanation

The strength of an electric field is determined by the amount of charge and the distance from the charge. More charge increases the field strength, while greater distance decreases it.

Tags

NGSS.MS-PS2-3

What happens when two electric fields interact?

• They cancel each other out completely.

• They create a magnetic field.

• They combine to form a new electric field.

• They disappear.

Answer explanation

When two electric fields interact, they combine to form a new electric field. This results in a superposition of the fields, leading to a resultant field that reflects the vector sum of the original fields.

Tags

NGSS.HS-PS3-5

Which of the following materials is an electric insulator?

• Copper

• Rubber

• Aluminum

• Silver

Answer explanation

Rubber is an electric insulator, meaning it does not conduct electricity. In contrast, copper, aluminum, and silver are all conductive metals that allow electric current to flow.

Which of the following materials is an electric conductor?

• Glass

• Wood

• Plastic

• Copper

Answer explanation

Copper is a well-known electric conductor, allowing electricity to flow easily. In contrast, glass, wood, and plastic are insulators, which do not conduct electricity effectively.

How do different materials hold electric charges?

• Conductors allow charges to move freely, insulators do not.

• Insulators allow charges to move freely, conductors do not.

• Both conductors and insulators allow charges to move freely.

• Neither conductors nor insulators allow charges to move freely.

Answer explanation

Conductors, like metals, allow electric charges to move freely due to their free electrons, while insulators, like rubber, restrict this movement, preventing charge flow. Thus, the correct choice is that conductors allow charges to move freely, insulators do not.

What is the process called when a charged object is brought near a neutral object, causing a separation of charges within the neutral object?

• Conduction

• Induction

• Insulation

• Convection

Answer explanation

The process is called induction. When a charged object is brought near a neutral object, it causes a separation of charges within the neutral object, leading to an induced charge distribution.

Which of the following best describes an electrically neutral object?

• It has more protons than electrons.

• It has more electrons than protons.

• It has an equal number of protons and electrons.

• It has no protons or electrons.

Answer explanation

An electrically neutral object has an equal number of protons and electrons, which balance each other out. If there are more protons or more electrons, the object would be positively or negatively charged, respectively.

What is the primary difference between conduction and induction?

• Conduction involves direct contact, while induction does not.

• Induction involves direct contact, while conduction does not.

• Both involve direct contact.

• Neither involves direct contact.

Answer explanation

Conduction occurs when heat is transferred through direct contact between materials, while induction transfers energy without direct contact, using electromagnetic fields. Thus, the correct choice is that conduction involves direct contact, while induction does not.

Tags

NGSS.MS-PS3-4

NGSS.MS-PS3-5

Why do electric fields have direction?

• Because they are scalar quantities.

• Because they are vector quantities.

• Because they are neither scalar nor vector quantities.

• Because they are imaginary.

Answer explanation

Electric fields have direction because they are vector quantities. Vectors have both magnitude and direction, which is essential for describing how forces act in space, unlike scalar quantities that only have magnitude.

Tags

NGSS.HS-PS3-5

NGSS.HS-PS2-4