A student builds different electromagnets using a 9 volt battery connected to an iron nail and with coils wrapped around it. Each electromagnet has a different number of coils wrapped around the nail. Which electromagnet will pick up the most paper clips?

Question

Electromagnet
Number of coils
A
10
B
20
C
30
D
40
(1 point)
A
B
C
D

Answer 1

In general, the strength of an electromagnet increases with the number of coils of wire wrapped around the core (in this case, the iron nail). More coils mean that there are more loops of wire through which the electric current flows, which enhances the magnetic field produced by the electromagnet.

Given the options:

• A: 10 coils
• B: 20 coils
• C: 30 coils
• D: 40 coils

Electromagnet D, with 40 coils, will be the strongest and should be able to pick up the most paper clips. Therefore, the answer is:

D

Answer 2

Which variable does not increase the strength of an electromagne
(1 point)
• Adding batteries to the electromagnet
• Increasing the distance between the coils
• Increasing the thickness of the wire
• Increasing the number of coils

Answer 3

The variable that does not increase the strength of an electromagnet is:

Increasing the distance between the coils.

Increasing the distance between the coils would actually reduce the effectiveness of the electromagnet by decreasing the density of the magnetic field. The other options, such as adding batteries (increasing voltage), increasing the thickness of the wire (which can allow for more current), and increasing the number of coils, can all contribute to a stronger magnetic field.

Answer 4

There are different methods to electrically charge an object. A girl slides down a plastic slide and her hair sticks up as she exits the bottom of the slide. This is an example of which method of building up an electric charge? (1 point)
• Neutralization
• Conduction
• Induction
• Friction

Answer 5

The scenario described, where a girl slides down a plastic slide and her hair sticks up as she exits, is an example of friction.

When she slides down the plastic slide, there is friction between her clothing (or hair) and the slide, which can cause electrons to transfer between the materials. This results in her hair becoming positively charged, causing it to repel from other strands of hair, making it stand up.

Therefore, the correct answer is:

Friction.

Answer 6

A teacher places a metal can on top of an insulating foam cup and touches the side of the foam cup with a negatively charged rod.
What will happen to the negatively charged electrons when the rod touches the metal can?
(1 point)
• The electrons will transfer to the foam cup because it is an insulator.
• The electrons will transfer to the can because it is an insulator.
• The electrons will transfer to the can because it is the conductor.
• The electrons will transfer to the foam cup because it is a conductor.

Answer 7

In this scenario, when the negatively charged rod touches the metal can, the electrons will move from the rod to the metal can. Since the metal can is a conductor, it allows the flow of electrons.

So the correct answer is:

The electrons will transfer to the can because it is the conductor.