Relativity

112-end science

What equation did Maxwell use that gave the speed of light?

1/sqrt(permittivity of free space x permeability of free space)

What is the speed of light?

3 x 10^8 m/s

The speed of light is ________ for all observers

Constant

Before Einstein’s theories, how did physicists attempt to explain the constant speed of light?

By claiming it was relative to a universal “ether” substance that filled the universe

What famous failed experiment tried to detect a changing speed of light?

Michaelson-Morley experiment

What did Einstein discover about time?

Time is relative to observers

What is time dilation?

The effect that someone moving relative to an observer

When an observer views themselves as stationary, they view others time as being….

Slowed down

If people on a spaceship travel 25 light years at 0.99c, they would only experience ______ light years of time

3.5

What is length contraction?

The effect that causes objects moving to be shorter than they are when stationary

When is relativity actually experienced in the real world?

It is always there, but is only noticeable near the speed of light

What is the Lorentz factor?

1/sqrt(1-v²/c²)

What does the Lorentz factor tell you?

How much time you experience versus how much time another observer experiences at speed v

If someone travels 30 light years, and the Lorentz factor is 3, how much time would they experience?

10 light years

What happens if light passes through glass?

It can be slowed down

Before relativity was discovered, what viewpoint of Faraday’s Law was considered the “correct” one?

The one from the magnet’s perspective

What are two interpretations of Faraday’s Law?

Current occurs because from the magnet’s perspective, charges are moving OR current occurs because the magnetic field moves relative to the charges

When did Einstein release his original paper on relativity?

1905

What was the title of Einstein’s original relativity paper?

On the Electrodynamics of Moving Bodies

Why does a proton feel an electric repulsive force when it views electrons as stationary?

Because it is moving relative to other protons, which repels the proton

The length contraction of protons in a wire is…

Very small

When a proton does not view itself as moving in a wire, what ultimately causes the proton to move?

Repulsive electric

When you calculate the strength of an electric repulsive force in a wire, it is the same as….

The magnetic force in the wire

Why are the electric and magnetic forces not fundamental?

They disappear from some frames of reference

What are the TRUE fundamental forces?

Strong nuclear force, weak nuclear force, gravity, and electromagnetism