Modern Physics Flashcards
What are the two simple postulates that Einstein made about special relativity?
1 . All the laws of physics are the same in every uniformly moving frame of reference.
2. The speed of light in a vacuum is always measured to be c = 3 x 10^8 m/s no matter the motion of the source of the light or the motion of the receiver of the light.
What does the second postulate mean in regards to time and space?
Time and space cannot be constant. The faster you go, the slower time moves and the shorter distances become in the direction you are going. Due to postulate one, you will not notice any of these changes.
What is an electron-volt?
The amount of energy required to change the potential of an electron by one volt.
What happens if a photon loses momentum and energy?
The wavelength increases and the frequency decreases.
In regards to wave-particle duality, what are the characteristics of long wavelengths such as radio waves.
They deomonstrate lots of wave behaviors due to their long wavelength.
They dont exhibit much in the way of particle properties due to their low energy.
In regards to wave-particle duality, what are the characteristics of short wavelengths such as gamma waves.
They exhibit lots of particle properties due to their high energy.
They demonstrate little in wave behaviours due to their short wave length.
What’s an alpha particle?
Two protons and two neutrons stuck together. (heavy)
What’s a beta particle?
An electron or a positron.
What’s a positron?
The antimatter equivalent of an electron. Same mass and charge as an electron, but a positive sign on its charge.
What’s a gamma particle
A gamma ray photon. (massless and chargeless)
What is α decay?
Happens when a nucleus emmits an alpha particle.
What is β decay?
Happens when a nucleus emmits a positron or an electron.
What occurs during a β+ decay?
A proton turns into a neutron and emits a positron.
What occurs during a β- decay?
A neutron turns into a proton. The change in charge is acounted for by the emitted electron.
What occurs during ɣ decay?
A gamma particle is a photon, with no mass or charge. A nucleus undergoing gamma decay does not change its outward appearance.