Simplified P1 - Wireless Signals & Stable Earth

Question 1

What are some examples of devices that use wireless technology?

Answer 1

Wireless technology is used by

• Radio & Television
• Laptops
• Mobile Phones

Question 2

What happens to radio waves in earths atmosphere?

Answer 2

Radio waves are reflected and refracted in Earth’s atmosphere.

Question 3

What can alter the amount of refraction?

Answer 3

The amount of refraction can be altered by the frequency of the waves, there is lower refraction at higher frequencies.

Question 4

What can cause interference in radio stations?

Answer 4

Interference can occur in unusual weather conditions where the radio signals travel further and the broadcasts interfere.

Question 5

How can you reduce interference in radio stations?

Answer 5

Interference in radio stations can be reduced through using digital signals.
Digital Audio Broadcasting, or DAB provides a greater range of Radio Stations however the Audio Quality is not as good as FM radio stations, but the Interference is completely eliminated.

Question 6

What do radio waves do in Earth’s ionosphere?

Answer 6

Radio waves are reflected from the ionosphere, they would behave like light in an optical fibre and undergo total internal reflection.

Question 7

What do radio waves do on water than they can not on land mass?

Answer 7

radio waves can be reflected by the water, but they can not be reflected by the land mass.

Question 8

How can radio waves reach aerials not in its line of sight?

Answer 8

Radio waves being continuously reflected by the ionosphere and the ocean can allow the radio waves to be received by an aerial not in a clear line of sight.

Question 9

What happens to Microwaves in the ionosphere?

Answer 9

Microwaves in the ionosphere can pass straight through.

Question 10

What happens to a microwave once it passes through the ionosphere?

Answer 10

When a microwave passes through the ionosphere it can be received by orbiting satellites and be amplified, and transmitted back to Earth.

Question 11

Where do communication satellites orbit?

Answer 11

Communication Satellites orbit above the equator and take 24 hours to orbit Earth.

Question 12

What happens to Radio Waves when they meet an obstruction?

Answer 12

Radio waves are diffracted when they meet an obstruction.

Question 13

What needs to be taken into account when transmitting signals to a satellite?

Answer 13

Refraction in the atmosphere needs to be taken into account when sending a signal to a satellite.

Question 14

Why does the transmitting aerial need to send a focused beam?

Answer 14

The transmitting aerial needs to send a focused beam because the receiving aerial is very small.

Question 15

How is energy lost when transmitting signals?

Answer 15

Some energy is lost form the edge of the transmitting aerial because of diffraction.

Question 16

What is the purpose of a seismograph?

Answer 16

A seismograph shows the different types of earthquake wave

http://www.calvin.edu/academic/geology/seismology/Virginia%20Quake%208-23-2011.jpg

Question 17

What do L waves do?

Answer 17

L waves travel round the surface very slowly.

Question 18

What are P waves?

Answer 18

P waves are longitudinal pressure waves.

Question 19

Where do P waves travel and how fast?

Answer 19

P waves travel through the Earth and they travel between 5 km/s and 8 km/s.

Question 20

What materials can P waves pass through?

Answer 20

P waves can pass through Solids and Liquids.

Question 21

What are S waves?

Answer 21

S waves are transverse waves.

Question 22

What are transverse waves?

Answer 22

Transverse waves are a wave in which the vibrations are at a right angles to the direction of travel.

Question 23

Where do S waves travel and how fast?

Answer 23

S waves travel through the Earth at speeds between 3 km/s and 5.5 km/s.

Question 24

What materials can S waves pass through?

Answer 24

S waves can only pass through Solids.

Question 25

What happens when P waves travel through the Earth?

Answer 25

When P waves travel through the Earth they are refracted by Earth’s core.

Question 26

What can P waves help figure out?

Answer 26

P waves, when refracted by the Earth’s core allow scientists to work out the size of the Earth’s core due to the path the P waves take.

Question 27

What happens to S waves when they pass through the Earth?

Answer 27

When S waves pass through the Earth they can not be detected on the other side, this is because S waves can not travel through liquids.

Question 28

What information can S waves not being detected on the opposite side of Earth to an earthquake provide?

Answer 28

S waves not being detected on the opposite side of the Earth where an earthquake takes place allow scientists to deduce that the Earth’s core is liquid as S waves can not pass through it.

Question 29

What causes a tan?

Answer 29

A tan is caused by the action of ultraviolet light on the skin.

Question 30

What is melanin?

Answer 30

Melanin is a pigment that produces a tan.

Question 31

What produces melanin?

Answer 31

Cells in the skin produce Melanin.

Question 32

Why do people with darker skin not tan as easily?

Answer 32

People with darker skin do not tan as easily because the ultraviolet radiation is filtered out by the melanin, the darker the skin the greater the amount of melanin.

Question 33

What is one way to reduce the chance of getting a tan?

Answer 33

Using sunscreen with a high SPF will reduce the risks of a tan and lower the chance of getting a tan.

Question 34

What is the formula for the maximum length of time to spend in the sun?

Answer 34

Published normal burn time x SPF = Maximum length of time to spend in the sun.

Question 35

Where is Ozone found?

Answer 35

Ozone is found in the stratosphere.

Question 36

What does Ozone do?

Answer 36

Ozone in the stratosphere helps to filter out and absorb ultraviolet radiation.

Question 37

What are CFCs doing to the ozone layer?

Answer 37

CFC gases from aerosols and fridges destroy ozone and reduce the thickness of the ozone layer.
– This increases the potential danger to humans

Question 38

Where is the ozone layer thinnest in the world?

Answer 38

The ozone layer is at its thinnest above the South Pole because ozone depleting chemicals work best in cold conditions.

Question 39

What do scientists use to monitor the thickness of the ozone layer?

Answer 39

Scientists are monitoring the thickness of the ozone layer using satellites.