P1.1 Visible Light And The Solar System Flashcards
What is the geocentric model?
The model of the solar system that the ancient greeks believed to be correct, featuring the earth at the centre of the solar system.
What is the heliocentric model?
The model of the solar system that replaced the geocentric model, featuring the sun at the centre, with all planets orbiting in circles.
How do scientists know so much about the universe?
Visible light.
What is wavelength?
The distance from one peak in a wave to the next.
What is wave frequency?
How many complete waves pass a certain point in one second.
What is amplitude?
The height of the wave from the mid-line to the peak.
What is the formula for speed (m/s)?
Speed = Frequency* Wavelength
What is the formula for wave speed?
Wave speed = distance/time.
What is a transverse wave?
A wave that vibrates at 90 degrees to the direction of travel.
What are some examples of transverse waves?
Light and EM waves
S-waves
Waves on strings and springs
Ripples on water.
What are longitudinal waves?
Waves in which the vibrations move in the same direction as the direction of travel.
What are some examples of longitudinal waves?
Sound and ultrasound
P-waves
A slinky spring
How are waves reflected?
Waves are reflected when some of the energy reaches a denser medium and some of the energy is reflected at the boundary.
What is the angle of incidence?
The angle between where the light hits the medium and a vertical straight line.
What is the angle of reflection?
The angle between the ray of reflection and a vertical straight line. It is the same as the angle if incidence.
What is refraction?
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.
What three rays are there in refraction, in the order that they appear in?
Incident ray, refracted ray, emergent ray.
What are converging lenses?
Convex lenses that converge parallel rays of light to a focus.
What is the focal point?
The point where all rays of light refracted by a lens meet.
What is focal length?
The length from the lens to the focal point
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What lenses are used in a refracting telescope?
An objective lens and an eyepiece lens.
How does a refracting telescope work?
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.
What are concave mirrors?
A mirror that has a disc shape with a dip in the middle.
How does a reflecting telescope work?
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.
What is a real image?
When light comes together to form an image on a ‘screen’.
