Turning Points : Energy And Mass Flashcards
What was the aim of the Michelson-Morley experiment?
The aim was to observe a difference in the speed of the parallel and perpendicular beams of light, and hence determine the absolute speed of light relative to the ether.
What was the set up of the Michelson-Morley experiment ?
Monochromatic light hit a beam splitter, and this sent two beams of light perpendicular to each other, to a plane mirror. Once the light hit the plane mirror, it was reflected back to the beam splitter and the light recombined, creating an interference pattern. Bright fringes are seen when the two light beams are in phase, and dark fringes are seen when the light beams are out of phase. The interferometer was rotated, to swap the perpendicular beams with the parallel beam top earth motion.
How did the fringe position shift?
By changing the distance to the mirror, this changes the path, and therefore the fringes shift.
What is an inertial frame of reference?
This is a reference frame that is moving at constant velocity, unless acted on by a force.
What are the two postulates that make up special relativity ?
The laws of physics are the same in all intertial frames of reference .
The speed of light is invariant in all inertial frames of reference.
How does time dilation work?
The time moves slower for an observer, who is moving relative to another object at rest.
At rest (person on train) experiences faster time.
The observer (person on platform) experiences slower time.
How does length contraction work?
The length of an object shrinks when viewed by a stationary observer.
Moving object - longer length
Stationary observer - shorter length
What happens to masses as objects approach the speed of light?
As v approaches c, the mass becomes infinite, so no amount of force can accelerate the mass further, and therefore the speed can never reach the speed of light.
