Flashcards in Turning points - Relativity Deck (18)
TP Chapter 3 Q) Define absolute motion
All objects including light move relative to a fixed background, called the ether.
TP Chapter 3 Q) Describe the Michelson – Morley interferometer experiment
Light is sent to a partoa;l reflector so it is split into two. The light travels separately to two different mirrors and then reflects back to a detector.
TP Chapter 3 Q) Describe the results that were expected to be seen from the Michelson – Morley interferometer experiment
Rotating the apparatus 90 degrees will cause the interference pattern to change. Light travelling parallel to the motion of the Earth should take longer than light travelling perpendicular.
TP Chapter 3 Q) Describe the observed results from the Michelson – Morley interferometer experiment
There was no effect of rotating the apparatus and no effect of the experiment happening at different times of the day and year.
TP Chapter 3 Q) Describe the conclusion from the Michelson – Morley interferometer experiment
It is impossible to detect absolute motion, the ether doesn’t exist. The speed of light is invariant.
TP Chapter 3 Q) Define an inertial frame of reference
Newton's law is obeyed. An inertial frame must be stationary or at a constant speed.
TP Chapter 3 Q) State the two postulates of Einstein’s theory of special relativity
The laws of physics have the same form in all inertial frames. The speed of light is invariant.
TP Chapter 3 Q) why could the special theory of relativity not be applied on a journey to a black hole?
Gravity changes so you would be accelerating so it wouldn’t be an inertial frame.
TP Chapter 3 Q) Explain the meaning of the speed of light is an invariant
The speed of light is measured to be the same in all reference frames by all observers.
TP Chapter 3 Q) Define time dilation
The increase in time measured by an observer who is moving at a constant velocity in relation to the two events.
TP Chapter 3 Q) Define proper time
The time interval between two events as measured by an observer that is stationary in relation to the events.
TP Chapter 3 Q) Describe how muon decay is used as evidence for special relativity
Muons are created in the upper atmosphere and travel towards the Earth's surface. Due to their short half life we would expect most muons to decay before they reach the surface. As they travel close to the speed of light time is dialated and the majority of muons each the earths surface.
TP Chapter 3 Q) Define length contraction
A moving object will look shorter to an external observer.
TP Chapter 3 Q) Describe Bertozzi’s experiment
Electrons are accelerated and time of flight is measured with an oscilloscope. Velocity is calculated by using distance/time. Electrons collide with an aluminium plate where temperature rise is measured. Energy of the electrons calcualted.
TP Chapter 3 Q) Explain how Bertozzi’s experiment provides evidence for special relativity
The speed of electrons increased up to the speed of light. The kinetic energy continues to increase so mass must be increasing.
TP Chapter 3 Q) Define rest mass
The mass of a stationary object
TP Chapter 3 Q) Define relative mass
The mass of an object which is moving close to the speed of light