Unit 3 Final REVIEW (8th: Electricity and Magnetism)

Shrek claims that Earth has a magnetic field. Which evidence would best support Shrek's claim?

• Shrek creates a working circuit that illuminates a bulb using wire and a battery.

• Shrek turns in all directions with a compass and the needle always points north.

• Shrek receives a shock after walking across the carpet and touching a doorknob.

• Shrek rolls a ball down a large hill and the ball comes to a complete stop at the bottom

Answer explanation

The compass needle consistently pointing north indicates the presence of Earth's magnetic field, as it aligns with magnetic north. This directly supports the student's claim about Earth's magnetic field.

Tags

GA.S8P5.a

Igor and Arthur each have a ball. The diagrams show the balls with their masses and the distances between them. In which diagram do Igor and Arthur experience the least gravitational force between their balls?

• I

• II

• III

• IV

Answer explanation

Diagram IV shows the least gravitational force because it likely represents the greatest distance between masses or the smallest mass, both of which reduce gravitational attraction according to Newton's law of gravitation.

Tags

GA.S8P5.a

Shrek and Aurora each have a charge. If their charges attract each other, then which of the following is true?

• Both charges must be positive.

• Both charges must be negative

• Both charges must be different.

• Both charges must be equal in value.

Answer explanation

For two charges to attract, they must be of opposite types: one positive and one negative. Therefore, the correct statement is that both charges must be different.

Tags

GA.S8P5.a

Viktor and Bella are investigating a magnet using iron filings, as shown in the picture. Viktor claims that the magnetic fields are not the same across the magnet. Using the picture, what evidence best supports Viktor's claim?

• The magnetic fields of the magnet are strongest at both poles.

• The magnetic fields of the magnet are strongest at the north pole.

• The magnetic fields of the magnet are strongest at the south pole.

• The magnetic fields of the magnet are strongest at the middle

Answer explanation

The statement that the magnetic fields are strongest at both poles supports the student's claim, as it indicates that the magnetic field strength varies across the magnet, contradicting the idea of uniformity.

Tags

GA.S8P5.a

Ratatouille and Pinocchio are experimenting with a wire and a battery in their science class. They notice that when electrical current flows through the wire, it can produce a certain type of force. Which type of force is produced by the electrical current?

• Chemical

• Gravitational

• Magnetic

• Nuclear

Answer explanation

Electrical current generates a magnetic field, producing magnetic forces. This is the principle behind electromagnets and electric motors, making 'Magnetic' the correct answer.

Tags

GA.S8P5.a

Arthur and Viktor each have an electric charge. The electric force between their charges increases when

• both charges become negative.

• both charges become positive.

• the charges get closer together.

• the charges get farther apart.

Answer explanation

The electric force between two charges increases when they get closer together due to Coulomb's law, which states that force is inversely proportional to the square of the distance between charges.

Tags

NGSS.MS-PS2-5

NGSS.MS-PS2-3

Shrek and Arthur each have a block, one weighing 250 g and the other weighing 150 g, placed 0.5 m apart as shown. What will happen to the force of gravitational attraction between the blocks if Shrek doubles the size of his block?

• It will increase.

• It will decrease.

• It will stay the same.

• It will repel.

Answer explanation

The force of gravitational attraction is directly proportional to the product of the masses of the objects. If one object's size (and thus mass) is doubled, the gravitational force will increase.

Tags

GA.S8P5.a

Bella and Arthur attach two identical balloons (X and Y) to the ceiling using a nylon thread so that the balloons are near each other. The table shows the observations from three different activities performed with the balloons.

What evidence supports that there is a non-contact force between the balloons?

• The balloons are not in contact and tend to move away from each other when both are rubbed with wool.

• The balloons are not in contact and tend to move away from each other when both are rubbed with rubber.

• The balloons are not in contact and tend to move close to each other when both are rubbed with a glass rod.

• The balloons are not in contact and tend to move close to each other when both are rubbed with wool.

Answer explanation

The correct choice indicates that when both balloons are rubbed with wool, they move away from each other, demonstrating a non-contact force (like static electricity) acting between them, despite not being in contact.

Tags

GA.S8P5.a

Ernie drops an apple from a tree, Igor uses a magnet to pick up some nails, and Cinderella combs her hair with a plastic comb. Each of these non-contact forces has an area of influence surrounding it.  What is this area called?

• gravitational attraction

• influence center

• field 

• attraction 

Answer explanation

The area surrounding a non-contact force where it can exert influence is called a 'field'. This term encompasses gravitational, electric, and magnetic fields, which describe how forces act over a distance.

Tags

GA.S8P5.a

Which drawing below represents the electric field surrounding two objects that have opposite charges or equal strength?

• 
• 
• 
• 

Tags

GA.S8P5.a