Introduction to Electromagnetism
Unit 1
What is inside an atom? * A positively charged nucleus composed of protons and neutrons * Electrons that surround the nucleus
What are isotopes?
Isotopes are atoms with the same number of protons and different numbers of electrons
How do we represent different atoms?
What is specific charge?
The specific charge of a particle is defined as its charge divided by its mass
What keeps protons and neutrons in a nucleus together?
A stable isotope has nuclei that do not disintegrate, so there muse be a force holding them together. We call this force the strong nuclear force because it overcomes the electrostatic force of repulsion between the protons in the nucleus and (except in unstable nuclei) keeps the protons and neutrons together.
Why are some nuclei stable and others unstable?
Whether nuclei are stable or unstable depend on their neutron:proton ratio.
What happens when an unstable nucleus emits an alpha or beta minus particle?
Alpha radiation consists of alpha particles which each comprise of 2 protons and 2 neutrons.
Beta radiation consists of fast moving electrons. A beta minus particle is emitted because a neutron is changing into a proton.
What is a photon?
A photon is a ‘packet’ of quantum of electromagnetic waves. An electromagnetic wave consists of an electric wave and a magnetic wave which travel together and vibrate: *at right angles to each other and to the direction in which they are travelling. *in phase with each other. As you can see the two waves reach peak together so they are in step. When waves do this we say they are ‘in phase’.
What is the energy of a photon?
Photon energy E=hf
How many photons does a light source emit every second?
A laser beam consists of photons of the same frequency. The power of a laser beam is the energy per second transferred by the photons. For a beam consisting of photons of frequency f, the power of the beam=nhf where n is the number of photons in the beam passing a fixed
What is inside an atom? * A positively charged nucleus composed of protons and neutrons * Electrons that surround the nucleus
What are isotopes?
Isotopes are atoms with the same number of protons and different numbers of electrons
How do we represent different atoms?
What is specific charge?
The specific charge of a particle is defined as its charge divided by its mass
What keeps protons and neutrons in a nucleus together?
A stable isotope has nuclei that do not disintegrate, so there muse be a force holding them together. We call this force the strong nuclear force because it overcomes the electrostatic force of repulsion between the protons in the nucleus and (except in unstable nuclei) keeps the protons and neutrons together.
Why are some nuclei stable and others unstable?
Whether nuclei are stable or unstable depend on their neutron:proton ratio.
What happens when an unstable nucleus emits an alpha or beta minus particle?
Alpha radiation consists of alpha particles which each comprise of 2 protons and 2 neutrons.
Beta radiation consists of fast moving electrons. A beta minus particle is emitted because a neutron is changing into a proton.
What is a photon?
A photon is a ‘packet’ of quantum of electromagnetic waves. An electromagnetic wave consists of an electric wave and a magnetic wave which travel together and vibrate: *at right angles to each other and to the direction in which they are travelling. *in phase with each other. As you can see the two waves reach peak together so they are in step. When waves do this we say they are ‘in phase’.
What is the energy of a photon?
Photon energy E=hf
How many photons does a light source emit every second?
A laser beam consists of photons of the same frequency. The power of a laser beam is the energy per second transferred by the photons. For a beam consisting of photons of frequency f, the power of the beam=nhf where n is the number of photons in the beam passing a fixed