Quiz on Tides

What is the main cause of ocean tides?

• The Moon ✓ (Correct answer)
• Strong winds
• Underwater currents
• The Earth's spin

Source: The Moon's gravity tugs the oceans into bulges that we feel as tides.

How many high tides do most coasts get each day?

• One
• Two ✓ (Correct answer)
• Six
• Twelve

Source: Most coasts get two highs and two lows roughly every 24 hours.

Besides the Moon, what else noticeably pulls on the oceans?

• Mars
• Pluto
• The Sun ✓ (Correct answer)
• Jupiter

Source: The Sun pulls too, but being so far off its tidal effect is weaker than the Moon's.

The strongest tides, at new and full moon, are called?

• Spring tides ✓ (Correct answer)
• Neap tides
• Rip tides
• Storm tides

Source: "Spring" here means to leap up, nothing to do with the season.

Water trapped among rocks when the sea retreats forms a?

• Lagoon
• Whirlpool
• Geyser
• Rock pool ✓ (Correct answer)

Source: These rock pools become miniature worlds for crabs, anemones and snails.

Roughly how long passes between one high tide and the next?

• About 6 hours
• About 12 hours ✓ (Correct answer)
• About 24 hours
• About 1 week

Source: Each high tide arrives about every 12 hours and 25 minutes, chasing the Moon.

A neap tide, with the smallest range, happens at which Moon phase?

• Full moon
• New moon
• Half moon ✓ (Correct answer)
• Crescent moon

Source: At half moon the Sun and Moon pull at right angles, flattening the range.

What is the height difference between high and low water called?

• Tidal wave
• Tidal range ✓ (Correct answer)
• Sea swell
• Ocean current

Source: Tidal range can be a few centimetres or, at the Bay of Fundy, over 15 metres.

The Bay of Fundy, home to the world's highest tides, lies in which country?

• Norway
• Australia
• Japan
• Canada ✓ (Correct answer)

Source: The Bay of Fundy's tides can rise the height of a four-storey building.

Tidal power stations harness the moving tides to produce what?

• Salt
• Drinking water
• Electricity ✓ (Correct answer)
• Natural gas

Source: Tidal turbines spin like underwater windmills to make electricity.

At Mont-Saint-Michel, the incoming tide is famously said to rush in as fast as a?

• Walking person
• Galloping horse ✓ (Correct answer)
• Speeding car
• Flowing river

Source: Locals warn the tide there gallops in faster than you can run.

Many anglers prefer a moving tide over slack water because?

• The water is warmer
• The Moon attracts fish
• Fish feed as water moves ✓ (Correct answer)
• Fish sleep at high tide

Source: Moving water stirs up food, so fish feed actively on a running tide.

A surge of seawater rushing upstream against a river's flow on a rising tide is a?

• Tidal wave
• Storm surge
• Waterfall
• Tidal bore ✓ (Correct answer)

Source: A tidal bore can send surfers riding a single wave for miles upriver.

The ocean bulges toward the Moon, but surprisingly it also bulges where?

• On the far side of Earth ✓ (Correct answer)
• At the North Pole only
• Near the equator only
• Directly under the Sun

Source: A matching bulge forms on Earth's far side, giving us two high tides.

Exceptionally high tides that can flood coastal roads, often at new or full moon, are nicknamed?

• Rogue tides
• Red tides
• King tides ✓ (Correct answer)
• Rip tides

Source: King tides aren't from a king, just the Moon at its closest and aligned.

The strip of shore covered at high tide and exposed at low tide is the?

• Intertidal zone ✓ (Correct answer)
• Continental shelf
• Abyssal plain
• Coral shelf

Source: The intertidal zone is one of nature's toughest neighbourhoods to live in.

The world's first major tidal power plant, opened in 1966, operates in which country?

• China
• France ✓ (Correct answer)
• United States
• Brazil

Source: France's Rance estuary plant pioneered tidal power back in 1966.

Tides arise not from the Moon's gravity alone, but specifically from?

• The Moon's total weight
• The difference in pull across Earth ✓ (Correct answer)
• The Moon's magnetic field
• The Moon's reflected light

Source: It's the difference in the Moon's pull across Earth, not its raw gravity, that makes tides.

The Sun is far heavier than the Moon yet raises smaller tides, mainly because?

• It is hotter
• It only acts by day
• It lacks gravity in space
• It is far more distant ✓ (Correct answer)

Source: Tidal force fades with the cube of distance, so the distant Sun loses out.

Some coasts, like parts of the Gulf of Mexico, get just one high tide daily. This pattern is called?

• Diurnal tides ✓ (Correct answer)
• Semidiurnal tides
• Mixed tides
• Equatorial tides

Source: Diurnal tides give just one high and one low each day instead of two.