just search up the answer/ definition to all of them, rephrase into own words, then do the same for examples.
Answer: find the answer in the explanation
Explanation:
When a magnet is placed at the centre of the paper, and the nails are sprinkled on the paper, what will happen to the nails is that, the nails will form a pattern on the paper according to the magnetic field of the bar magnetic pole.
Other phenomena you can observe are:
1.) The nails will align themselves and show some lines of forces which is equivalent to the magnetic field lines
2.) The direction of the line of forces
3.) The strength of the magnetic field pole.
Answer:
the primary coil current produces a magnetic field, which changes as the current changes. the iron core increases the strength of the magnetic field. the changing magnetic field induces a changing potential difference (voltage) in the secondary coil.
The wavelength

of the wave is 160 m, and this is the distance between two consecutive crests. The boat is located at a crest of the wave, this means that the first trough is located 80 meters from the boat (because the distance between a crest and a trough is half the wavelength).
The speed of the wave is

so the time the boat takes to reach the first trough is
Answer:
D
Explanation:
If you list and compare, the elephants hearing range is the closest to a humans.
Humans: 20-20,000
Elephant: 16-12,000
While the others are either too much more or less than a humans.
Bat: 2,000-110,000
Dolphin: 90-105,000
Chicken: 125-2,000