Magnetic and Electric Fields Review

When Bethany walks across a carpet, her socks pick up many electric charges. Later in the day, these charges are no longer present on her socks. What most likely happened to the charges?

• The charges disappeared.
• The charges switched signs
• The charges transferred to another object.
• The charges broke apart into smaller particles.

The diagram shows two pairs of charged objects. Objects A and B are interacting with each other, and objects C and D are interacting with each other. Based on the diagrams, which statement is true?

• There are NO electric forces because the charges in each pair of objects cancel.
• The electric force between A and B is SMALLER than the electric force between C and D.
• The electric force between A and B is BIGGER than the electric force between C and D.
• The electric force between A and B is THE SAME in magnitude (size) to the electric force between C and D.

Jesse tests three magnets by observing how many paper clips he can attach to the north pole in a single chain. He warms the magnets in the oven for a few minutes and repeats his procedure. The data is shown in the table. Which statement BEST explains Jesse’s observations?

• Warming a magnet aligned some of the magnetic domains.
• The forces produced by a magnet naturally become weaker over time.
• Warming a magnet causes the magnetic force to decrease.
• The poles of the magnet become reversed when warmed and cause it to repel the paper clips

Rohit is using a compass to investigate magnetic forces. Which of these will cause the compass to change direction?

• plastic paper clips
• a wooden doorknob
• the wire in a cord he is using to charge a cell phone
• the wire going from the wall to a lamp that is turned off.

What set of charged objects would have the WEAKEST force?

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Which set of magnets would have the strongest force between them?

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A student dips the end of a magnet into a pile of iron filings. When they tell the teacher they can clean the magnet with soap and water, the teacher just shakes their head in disbelief. Using what you have learned about magnets explain to the student why they cannot clean the magnet with soap and water.

Explain what is happening between the hair and the balloon? a) What type of force is present? b) Is this showing attraction or repulsion? c) What is the charge on the hair?

Brittany wanted to make a model of an object with a neutral charge. a) Is the model correct (yes/no)? b) How do you know if it is correct or incorrect?