Lenses
What are the two types of lenses?
Concave and Convex
What are the two types of waves?
Transverse and Longitudinal
State the law of reflection
angle of incidence = angle of reflection
How does fiber optics work?
It sends information down a glass or plastic pipe
The ray used to kill bacteria in food, and to kill cancer in radiotherapy is...
gamma rays
What lense is used by people with myopia?
Concave lenses
State an example of longitudinal and transverse waves
Longitudinal: sound
Transverse: light/water
Why do we see a clear image in a mirror, but not in a sheet of paper?
The mirror has a smooth surface, so the reflected rays bounce off without being scattered. A paper has a rough surface, so the rays reflect and bounce off all scattered.
How does light travel in these cables?
It passes down bouncing repeatedly off the walls because (internal reflection)
The ray used to look for broken bones in hospitals...
x-rays
What is wavelength?
It is the distance from the crest to crest or trough to trough. It is measured in meters and the symbol is lambda
Why is a cell phone named cell?
The network required for cells to wok consist in towers, antennas, and transmitters divided into areas called cells
Distinguish between real and virtual images
real: image that exists in space (projector, movie theather lens, because you can "catch" the image)
virtual: image formed by the eye from the light rays appearing to diverge from an optical component (mirror - you can't catch the image)
Why does an optical fiber work better than a copper wire?
It transmits information faster,
it has less signal loss,
and there is no interference
ultraviolet
What is amplitude?
It is the size of the wave. It is measured from the equilibrium to the CREST
Can electromagnetic waves from your phone damage your cells-tussues-organs?
No, only high energy waves! They have enough energy to remove an electron from an atom (ionization). This damages cells by killing them, or mutating, causing cancer.
ex: x-rays, ultraviolet, and gamma rays
Why is the image in a mirror switched from left to right?
The lateral inversion is not caused by the mirror, but by our perception of the mirror image. The front-back reversal is what causes the lateral inversion that confuses us so.
your image is looking back at you, as if you had turned around to face yourself. So if you raise your left hand, your image in the mirror will raise the right
State some uses of optical fibers
Used in grills for cooking and for communication in optical fibers...
infrared
What is frequency?
The number of complete waves to pass a point every second. It is measured in Hertz
Where do you texts go?
The message signals are picked up by the closest tower to them, which converts the radio waves into a digital electrical impulse and passes it to the mobile switching center. The messages stay there until you are located by the network.
distinguish between conversion and diversion of rays
conversion: when the distance between two things decrease with distance traveled.
diversion: when the distance between to things increases with distace traveled
What is total internal reflection?
It occurs when the angle of incidence of the light is above a critical angle, reflecting light back at the boundary of two media
used to heat food/communicate with satellites/
microwaves