The two differences you see when comparing the four chambers of the heart is that the arteries have a thicker wall and veins have thin walls and that the arteries carry oxygenated blood away from the heart which means they get more pressure than veins.
Answer:
A lunar eclipse occurs when the Moon passes directly behind the Earth into its umbra (shadow). This can occur only when the sun, Earth and moon are aligned (in "syzygy") exactly, or very closely so, with the Earth in the middle.
Explanation:
Answer:
objective lenses
Explanation:
objective lenses with different magnifications, screwed into a circular "nosepiece" which may be rotated to select the required lens.
