Question

1. how is a magnet able to pick up bits of metal without actually touching them? a. the magnet is surrounded by an electric field that attracts the metal. b. the metal exerts a repulsive force on the magnet. c. there is an invisible magnetic field around the magnet where it exerts magnetic force. d. the electric force from the magnet attracts the bits of metal. 4. explain phenomena a magnet is placed on a refrigerator to hold up a calendar. as the magnet approaches the refrigerator, the potential energy between the magnet and the refrigerator decreases. explain why.

Explanation:

Step1: Analyze question 3

A magnet has an invisible magnetic - field around it. This magnetic field can attract magnetic materials like bits of metal without physical contact.

Step2: Evaluate options for question 3

Option A is wrong as the magnet's field attracts, not repels. Option B is incorrect because the metal doesn't exert a repulsive force on the magnet in this context. Option D is wrong as it's the magnetic force, not the electric force. Option C is correct as the magnet's magnetic field attracts the metal.

Step3: Analyze question 4

The potential energy between two magnetic objects depends on the distance between them. The formula for magnetic potential energy related to distance is similar to that of gravitational or electrostatic potential energy in terms of the inverse - square relationship (in a simplified sense). As the distance \(d\) between the magnet and the refrigerator decreases, the potential energy \(U\) decreases according to the relationship \(U\propto\frac{1}{d}\) (simplified for the concept here). The magnetic force is doing work as the magnet moves closer to the refrigerator, converting potential energy into other forms (like kinetic energy if it was moving freely before sticking), so the potential energy decreases.

Answer:

1. C. There is an invisible magnetic field around the magnet where it exerts magnetic force on the bits of metal.
2. The potential energy between two magnetic objects is related to the distance between them. As the magnet approaches the refrigerator (distance decreases), the magnetic force does work, converting potential energy into other forms, resulting in a decrease in potential energy.