Term 4 Test- Light and the electromagnetic spectrum Flashcards
When does reflection occur?
A wave hits a boundary between two mediums and does not pass through, but instead stays in the original medium
What is the law of reflection?
Angle of incidence (i) = Angle of reflection (r)
When does refraction occur?
Refraction occurs when light passes a boundary between two different transparent media
At the boundary, the rays of light change direction because the light changes speed
When does total internal reflection occur?
The angle of incidence is greater than the critical angle and the incident material is denser than the second material
What is specular reflection?
Reflection from a smooth surface in a single direction
What is diffuse reflection?
Reflection from a rough surface causes scattering
If an object appears red what does this mean has happened?
Only red light has been reflected
All the other frequencies of visible light have been absorbed
What are the two types of lenses?
Converging and diverging
In ROYGBIV which of these has the longest wavelength
Red
In ROYGBIV which of these has the shortest wavelength
Violet
Describe a converging lens
Lenses that are thicker in the middle. A converging lens bend rays of light towards one another, bringing them to one point.c
Describe a diverging lens
Lenses that are thinner in the middle. A diverging lens bends rays of light away from each other.
What does the power of a lens mean?
The greater the power of the lens, the more light it bends
Is the power for a diverging lens positive or negative?
Negative
Is the power for a converging lens positive or negative?
Positive
Describe a real image
A real image is formed where light rays converge and are actually focused on a screen.
Describe a virtual image
A virtual image is formed by light rays which appear to diverge from that point, but do not actually do so.
What a properties of an electromagnetic wave?
- They are all transverse
- They travel at the same speed in a vacuum ( 3 x 10 to the power of 8 m/s)
- Transfer energy
List in the right order the electromagnetic spectrum
Radio waves, Micro waves, Infra red, Visible light, Ultra violet, X-rays, Gamma rays
What waves are commonly used by satellites?
Microwaves and Radio waves
What are problems of radiation with high energy?
Highly ionising and harmful to cells and tissues causing cancer.
When EM waves interact with matter to they speed up or slow down
Slow down, therefore the denser the substance the slower the wave
What different ways can EM waves move from one medium to another?
Transmitted, Absorbed, Reflected, Refracted
What type of waves can be used by satellites?
Microwaves and Radio waves
What are EM waves made up of?
EM waves are made up of oscillating electric and magnetic fields
Name two things infrared radiation can be used for?
- Monitor temperature
- Transfer information
Which type of EM wave has the highest frequency?
Gamma rays
True or False
Changes in atoms can generate EM waves?
True
What type of radiation is used in optical fibres?
Infrared radiation
Name some side effects of X-rays
Could cause cancer/ cell mutations/ damage cells
True or False
As an object’s temperature increases, the peak wavelength of the radiation it emits will become shorter.
True
If an objects temperature is constant, what can be said about the average power emitted and absorbed by that object?
The average power emitted by the object will be equal to the average power absorbed by the object.
True or False
Radiation from the sun can be absorbed by the Earth’s atmosphere
True
