P1.1 Visible Light And The Solar System

Question 1

What is the geocentric model?

Answer 1

The model of the solar system that the ancient greeks believed to be correct, featuring the earth at the centre of the solar system.

Question 2

What is the heliocentric model?

Answer 2

The model of the solar system that replaced the geocentric model, featuring the sun at the centre, with all planets orbiting in circles.

Question 3

How do scientists know so much about the universe?

Answer 3

Visible light.

Question 4

What is wavelength?

Answer 4

The distance from one peak in a wave to the next.

Question 5

What is wave frequency?

Answer 5

How many complete waves pass a certain point in one second.

Question 6

What is amplitude?

Answer 6

The height of the wave from the mid-line to the peak.

Question 7

What is the formula for speed (m/s)?

Answer 7

Speed = Frequency* Wavelength

Question 8

What is the formula for wave speed?

Answer 8

Wave speed = distance/time.

Question 9

What is a transverse wave?

Answer 9

A wave that vibrates at 90 degrees to the direction of travel.

Question 10

What are some examples of transverse waves?

Answer 10

Light and EM waves
S-waves
Waves on strings and springs
Ripples on water.

Question 11

What are longitudinal waves?

Answer 11

Waves in which the vibrations move in the same direction as the direction of travel.

Question 12

What are some examples of longitudinal waves?

Answer 12

Sound and ultrasound
P-waves
A slinky spring

Question 13

How are waves reflected?

Answer 13

Waves are reflected when some of the energy reaches a denser medium and some of the energy is reflected at the boundary.

Question 14

What is the angle of incidence?

Answer 14

The angle between where the light hits the medium and a vertical straight line.

Question 15

What is the angle of reflection?

Answer 15

The angle between the ray of reflection and a vertical straight line. It is the same as the angle if incidence.

Question 16

What is refraction?

Answer 16

When a wave hits a denser medium at an angle, it slows down as so bends towards the normal, a line at 90 degrees to the medium that the wave enters.

Question 17

What three rays are there in refraction, in the order that they appear in?

Answer 17

Incident ray, refracted ray, emergent ray.

Question 18

What are converging lenses?

Answer 18

Convex lenses that converge parallel rays of light to a focus.

Question 19

What is the focal point?

Answer 19

The point where all rays of light refracted by a lens meet.

Question 20

What is focal length?

Answer 20

The length from the lens to the focal point

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Question 21

What lenses are used in a refracting telescope?

Answer 21

An objective lens and an eyepiece lens.

Question 22

How does a refracting telescope work?

Answer 22

The objective lens converges the rays to form a real image at the focal point of the objective lens. The rays from the real image enter the eyepiece lens, which spreads them out, so that the leave at a wider angle and fill more of your retina, making the object appear magnified.

Question 23

What are concave mirrors?

Answer 23

A mirror that has a disc shape with a dip in the middle.

Question 24

How does a reflecting telescope work?

Answer 24

A large concave mirror collects the parallel rays of light. It reflects them onto a smaller second mirror placed in front of the large mirror’s focal point. The small mirror reflects the light through a hole in the large mirror. A real image is formed behind the mirror. An eyepiece lens magnifies this image.

Question 25

What is a real image?

Answer 25

When light comes together to form an image on a ‘screen’.