Electromagnetic and Gravitational Forces

How do you know when a pith ball is surrounded by an electric field?

• it will remain stationary when neutral objects are brought near it

• it will attract or repel other charged pith balls.

• it will attract a glass rod when it comes in contact with it.

• it will lose electrons and become negatively charged.

Tags

NGSS.MS-PS2-3

NGSS.MS-PS2-5

Predict what will happen when a balloon with a charge of -1 is brought near small pieces of paper that have a charge of +1.

• The balloon and the paper have the same charge, so they are attracted to each other.

• The balloon will repel the pieces of paper because they have the opposite charge.

• The balloon will attract the pieces of paper because the charges are opposite.

• The balloon will repel the pieces of paper because the charges are the same.

Tags

NGSS.MS-PS2-3

NGSS.MS-PS2-5

A -1 negatively charged pith ball is on a string between two heavy objects that are both positively charged. The object on the left has a charge of +6 and the object on the right has a charge of +3. Which direction will the -1 charged pith ball swing?

• to the right, because it is repelled more by the object with more positive charges on the left.

• to the left, because it is attracted more by the object with more positive charges on the left.

• to the right, because it is attracted more by the object with less positive charges on the right.

• to the left, because it is repelled more by the object with less positive charges on the right.

Tags

NGSS.MS-PS2-3

NGSS.MS-PS2-5

In an investigation, a student moves a compass farther and farther from a bar magnet. When the compass reaches a certain distance from the magnet, it no longer aligns with its magnetic field, and begins to point toward Earth's north pole. What conclusion can be made?

• The strength of the field decreases with distance, and a compass can show how far it extends

• The bar magnet’s field vanishes completely after only a few short centimeters and no longer deflects the compass needle from Earth's magnetic field.

• A compass cannot measure field strength unless connected directly to the magnet.

• The Earth’s magnetic field becomes weaker whenever a magnet is placed inside it so that the compass stops pointing north.

Tags

NGSS.MS-PS2-3

NGSS.MS-PS2-5

Below are two models of electromagnets connected to batteries of equal voltage. Which electromagnet would be able to lift the greater amount of paperclips, and why?

• Electromagnet B, because it has more coils which increases the strength of the magnetic field.

• Electromagnet A, because fewer coils make the magnetic field stronger.

• Electromagnet A, because it has a higher voltage which increases the strength of the magnetic field.

• Electromagnet B, because lower voltage always increases the strength of the magnetic field.

Tags

NGSS.MS-PS2-2

NGSS.MS-PS2-3

What happens to an electromagnet when the electric current in its wire is increased?

• Its magnetic field becomes stronger.

• It changes into a permanent magnet.

• Its magnetic field stays the same.

• Its magnetic field becomes weaker.

Tags

NGSS.MS-PS2-3

Why does increasing the size of the iron core improve an electromagnet?

• It lowers the electric current flowing through the wire.

• It boosts the strength of the magnetic field.

• It weakens the magnetic field.

• It raises the amount of electric current.

Tags

NGSS.MS-PS2-3

Students built an electromagnet by connecting both ends of a wire to a battery and wrapping the wire around a steel nail. At first, the nail lifted four paper clips. The students then added more coils of wire around the nail to test whether the electromagnet would become stronger.

Which result would best show that adding more coils increased the strength of the electromagnet?

• More wire was required to cover the nail.

• The nail was able to lift six paper clips.

• The battery eventually lost its charge.

• The wire still had to be connected to both battery terminals.

Tags

NGSS.MS-PS2-3

NGSS.MS-PS2-5

Students experimented with an electromagnet by turning up the current flowing through the wire.
What was the result of increasing the current?

• The magnetic field decreased in strength.

• The magnetic field increased in strength.

• The magnetic field did not change.

• The magnetic field changed direction.

Two students tested electromagnets to compare their strength. In each trial, they used a fresh 1.5 V battery. Alex’s final electromagnet was the strongest, lifting more paper clips overall than Jordan’s final electromagnet. However, they both neglected to record the data for how many paperclips were picked up on their data tables, and did not write their names on the paper. Use the information to decide which table belongs to Alex and which belongs to Jordan.

• Table 1: Jordan - this data table shows a greater number of coils for the final electromagnet, which means it would be weaker.

  Table 2: Alex - this data table shows a lesser number of coils for the final electromagnet, which means it would be stronger.

• Table 1: Alex - this data table shows a greater number of coils for the final electromagnet, which means it would be stronger.

  Table 2: Jordan - this data table shows a lesser number of coils for the final electromagnet, which means it would be weaker.

• Table 1: Alex - this data table shows a greater amount of battery voltage for all four electromagnets, which means they would be stronger than Jordan's

  Table 2: Jordan - this data table shows a less battery voltage for all four electromagnets, which means they would be weaker than Alex's

Tags

NGSS.MS-ETS1-2