Question

instructions: look up vocabulary words with the correct definition.
vocabulary words

1. electromagnetic
2. attract
3. repel
4. magnet
5. magnet field
6. ferrofluid
7. static electricity
8. electrical charge
9. van de graaff generation

reading questions:

1. if magnetic fields are invisible, how do we know they are there?
2. is an aluminum can magnetic or non - magnetic? why or why not?
3. why do the neodymium magnets come together and pulverize the fruit?
4. how are magnetic force and distance from an object related?
5. how can a nail become an electromagnet and magnetically attract paper clips?
6. do the balloon and plastic bag used in the levitation device have the same or opposite charges?

Explanation:

The problem involves concepts related to magnetism and electricity, which fall under the subfield of Physics (Natural Science). To answer the reading questions, we analyze each:

1. Magnetic fields are known to exist because they exert forces on magnetic materials (like iron filings aligning) or affect moving charges.
2. Aluminum is non - magnetic as it doesn't have magnetic domains that align to produce a magnetic field (unlike ferromagnetic materials like iron).
3. Neodymium magnets have strong magnetic attraction; when they come together, the large force between them crushes the fruit.
4. Magnetic force is inversely related to the square of the distance (similar to Coulomb's law for magnetism, \( F \propto \frac{1}{r^{2}} \) for point - like magnetic sources), so as distance increases, force decreases.
5. A nail becomes an electromagnet when a current - carrying wire is wrapped around it; the current produces a magnetic field that magnetizes the nail, allowing it to attract paper clips.
6. For the levitation device, if the balloon and plastic bag repel, they have the same charge (since like charges repel); if they attract, opposite charges (but levitation usually involves repulsion, so same charge).

Answer:

1. We know magnetic fields exist as they exert forces (e.g., on magnetic materials/charges).
2. Aluminum can is non - magnetic (no magnetic domain alignment).
3. Strong magnetic attraction between neodymium magnets crushes the fruit.
4. Magnetic force is inversely proportional to the square of the distance (\( F \propto \frac{1}{r^{2}} \)).
5. Wrap a current - carrying wire around the nail (electromagnet) to attract paper clips.
6. Same charges (for levitation via repulsion, typical in such devices).