Question

science matter and energy 2nd ed.
test 10 chapter 10
emma faith cleveland 861427 9
carefully read each statement and indicate whether it is true or false by filling in the corresponding
bubble.

1. the north pole of a magnet is attracted to the north pole of the earth.

true false

1. if a magnet is cut in half, one piece will have only the north pole, and the other will have only the

south pole.
true false

1. all of the planets in our solar system have magnetic fields.

true false

1. the magnetic poles of the earth are not stationary.

true false

1. the magnetic field produced by electrons flowing through a straight wire has no poles.

true false

1. the core of an electromagnet is a magnetically hard substance.

true false

1. the earths magnetic poles are called north and south because of their magnetic properties.

true false
choose the best answer and fill in the corresponding bubble.

1. the ____ is the most important cause of magnetism in magnetic materials.

spin of electrons orbital motion of electrons
spin of the atoms nuclei kinetic energy of the atoms

1. substances with several unpaired electrons per atom are called ____.

diamagnetic paramagnetic megamagnetic ferromagnetic

1. two magnets that are 10.0 cm apart are attracting each other with a force of 20.0 n. what will be the

force when they are 20.00 cm apart?
5.0 n 10 n 80 n 200 n

Explanation:

1.

The Earth's magnetic north pole is actually a south - seeking pole. Opposite poles attract. So, the north pole of a magnet is attracted to the Earth's magnetic south pole (which is near the Earth's geographic north pole).

2.

When a magnet is cut, each piece will have both a north and a south pole. Magnetic monopoles (a magnet with only one pole) do not exist in nature.

3.

Not all planets in our solar system have magnetic fields. For example, Mars has a very weak and patchy magnetic field, and Venus has an extremely weak magnetic field (almost negligible).

4.

The Earth's magnetic poles are constantly moving. This is due to the movement of molten iron in the Earth's outer core.

5.

The magnetic field around a straight current - carrying wire forms concentric circles. It does not have distinct north and south poles like a bar magnet.

6.

The core of an electromagnet is usually a magnetically soft material (like iron). Magnetically soft materials can be easily magnetized and demagnetized, which is useful for electromagnets that need to be turned on and off.

7.

The Earth's magnetic poles are named north and south based on their magnetic properties (similar to a bar magnet), not just for naming convenience.

8.

The spin of electrons is the most important cause of magnetism in magnetic materials. The orbital motion of electrons also contributes, but the spin is more significant. The spin of nuclei and the kinetic energy of atoms are not the main causes of magnetism in magnetic materials.

9.

Substances with several unpaired electrons per atom are called ferromagnetic. Diamagnetic substances have all electrons paired. Paramagnetic substances have a small number of unpaired electrons. Megamagnetic is not a standard term in this context.

10.

The force between two magnets is inversely proportional to the square of the distance between them (\(F\propto\frac{1}{r^{2}}\)). Let \(F_1 = 20N\), \(r_1=10cm\), and \(r_2 = 20cm\). Using the formula \(\frac{F_1}{F_2}=\frac{r_2^{2}}{r_1^{2}}\), we substitute the values: \(\frac{20}{F_2}=\frac{20^{2}}{10^{2}}=\frac{400}{100} = 4\). Then \(F_2=\frac{20}{4}=5N\).

Answer:

1. False
2. False
3. False
4. True
5. True
6. False
7. True
8. spin of electrons
9. ferromagnetic
10. 5.0 N