Matter And Radiation

Question 1

Specific charge

Answer 1

The specific charge of a charged particle is defined as its charge divided by its mass, we can calculate the specte charge of a charsed particle if we know the charge and the mass of the particle.

Question 2

Charge and mass

Answer 2

Proton- +1.60x10^-19 -charge. 1.67x10^-27-mas
Neutron has no charge and the same mass
Electron — 1.60 x 10-^-19 charge .9.11x10^-31mass

Question 3

Strong nuclear force

Answer 3

A stable isotope has nuclei that do not disintegrate, so there must in 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 keeps the protons and neutrons together

Question 4

Further points about strong nuclear forces

Answer 4

Its range is no more than about 3-4 femtometres (Im), This range is about the same as the diameter of a small nucleus. In comparison, the electrostatic force between two charged particles have an infinite range (.
• It has the same effect between two protons as it does between two
neutrons or a proton and a neutron
• It is an attractive force from 3-4 fm down to about 0,5 fm. At separations smaller than this, it is a repulsive force that acts to prevent neutrons and protons being pushed into each other.

Question 5

Alpha radiation plus write the equation

Answer 5

Alpha radiation consists of alpha particles which each comprise two protons and two neutrons. The symbol for an alpha particle is 4a2 because its proton number is 2 and its mass number is 4.

Question 6

Beta radiation plus write the equation

Answer 6

Beta radiation consists of fast-moving electrons.the symbol for this is B-) because its charge is equal and opposite to that of the proton and its mass is much smaller than the proton’s mass.

Question 7

Gamma radiation plus write the equation

Answer 7

Gamma radiation (symbol y) is electromagnetic radiation emitted by an unstable nucleus. It can pass through thick metal plates. It has no mass and no charge. It is emitted by a nucleus with too much energy, following an alpha or beta emission.

Question 8

Electromagnetic waves

Answer 8

Light is just a small part of the spectrum of electromagnetic waves.
Our eyes cannot detect the other parts.
In a vacuum, all electromagnetic waves travel at the speed of light,

An em wave consist 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

Question 9

Photons

Answer 9

Electromagnetic waves are emitted by a charged particle when it loses energy. This can happen when
• a fast-moving electron is stopped (or slows down or changes direction
• an electron in a shell of an atom moves to a different shell of lower energy.

Question 10

Em waves emitted

Answer 10

Electromagnetic waves are emitted as short bursts of waves, each burst leaving the source in a different direction. Each burst is a packet of electromagnetic waves and is referred to as a photon. The photon theory was established by Einstein in 1905, when he used his ideas to explain the photoelectric effect. This is the emission of electrons from a metal surface when light is directed at the surface.