Optics Lessons 5-9 Flashcards
How did Galileo try to measure the speed of light what were his results?
He tried to measure it with the distance between two distant hill tops by having an assistant cover and uncover a lamp and then he would do the same when he saw this and he figured the time gap between would be the time it takes for light to travel twice the distance of the hills. The issue he found was his reaction time was the major factor for how much time elapsed since he couldn’t do it instantly and with this he determined that light was either extraordinarily fast or instantaneous.
How did the Danish astronomer Ole Romer try to determine the speed of light?
he noticed the period of one of Jupiter’s moons changed depending on whether earth was moving toward or away from Jupiter he the difference in distance and time to calculate that light was traveling at 2.38x10^8 m/s which isn’t that far off from todays accepted value
How did Michelson try to measure the speed of light
he used a rotating mirror apparatus which reflects light to another mirror which then reflects the light back to the rotating mirrors and then to the sensor by doing so he made it so the distance between the external mirror multiplied by 2 divided by the period of the rotating mirrors / by the #of mirrors had to equal the speed of light for an output to be observed he observed the accepted value for the speed of light with this!!
When light reflects how does the incident rays angle compare to the reflected ray
they are equal angle from the normal which is perpendicular to the point of impact
where does an object appear to be when seen in a plane mirror
inside the mirror (this is called the virtual image)
Where does an object appear to be when seen in a converging mirror
it appears to be at a focal point in the (real) space or outside the mirror
Where does an object appear to be when seen in a diverging mirror (think of the back of a spoon)
The light rays are reflected away from a virtual focal point (note they never reach it just like plane mirrors but they appear to so when trying to find it draw reflected ray lines continuing into the mirror even though that’s not what happens!!!
How can you find the focal length of a mirror
focal length =the radius of curvature of a mirror divided by 2 or
1/focal length=1/distance to the object from the mirror + 1/distance to the image from the mirror
where do you draw lines from to find an image in a mirror
Line 1 is from the end of the object to the mirror parallel to the principle axis to the focal point
Line 2 is from the end of the object through the focal point to the mirror
Line 3 is from the center of curvature (2f) through the end of the object to the mirror and back
what is an index of refraction
It refers to the speed at which light travels through something it is always greater than or equal to 1 as the reference is light traveling through a vacuum
What is Snell’s Law
Refraction is the change in speed, wavelength, and direction of light caused by a change in medium
