Physics terms and definitions I do not understand yet

Question 1

Define transverse waves.

Answer 1

Motion in which all points on a wave oscillate along paths at right angles to the direction of the wave’s advance.

Question 2

Define longitudinal waves.

Answer 2

Wave consists of a vibration that takes place in the same direction as the advance of the wave.

Question 3

What does a polarising filter do?

Answer 3

Only allows oscillations in one plane.

Question 4

How is polarisation used as evidence of the nature of transverse waves?

Answer 4

Polarisation can only occur if a wave’s oscillations are perpendicular to its direction of travel (as they are in transverse waves).

Question 5

What is Polarisation?

Answer 5

A property of transverse waves which specifies the geometrical orientation of the oscillations.

Question 6

How does polarisation filters work?

Answer 6

It has the property of transmitting light that vibrates in one direction while absorbing light that vibrates in a perpendicular direction.

Question 7

What is a stationary wave?

Answer 7

A wave which transfers no energy and whose positions of maximum and minimum amplitude are constant.

Question 8

What are the conditions for a stationary wave to be produced?

Answer 8

The waves must be of the same frequency, wavelength and amplitude.
They must be travelling in opposite directions.

These conditions are often met when a wave is reflected back onto itself.

Question 9

How are stationary waves produced?

Answer 9

Stationary wave is formed from the superposition of two progressive waves, travelling in opposite directions in the same plane, with the same frequency, wavelength and amplitude.

Question 10

Describe the first harmonic for a stationary wave with two closed ends.

Answer 10

It consists of two nodes at either end and an antinode in the middle.

Question 11

Describe the second harmonic for a stationary wave with one open end and one closed end.

Answer 11

It consists of two nodes and two antinodes, with one of the nodes at the closed end and one of the antinodes at the open end.

Question 12

What are the main constituents (one of the parts that a substance or mixture is made of) of an atom

Answer 12

Proton, Neutron and Electron

Question 13

What is a nucleon?

Answer 13

A constituent of the nucleus: a proton or a neutron.

Question 14

What is an isotope?

Answer 14

A version of an element with the same number of protons but a different number of neutrons.

Question 15

State the use of radioactive isotopes.

Answer 15

Carbon dating - the proportion of carbon-14 in a material can be used to estimate its age.

Question 16

What is the strong nuclear force?

Answer 16

The fundamental force that keeps the nucleus stable by counteracting the electrostatic force of repulsion between protons.

Question 17

Describe the range of the strong force?

Answer 17

Repulsive up to 0.5fm
Attractive from 0.5-3fm
Negligible past 3fm

Question 18

What makes a nucleus unstable?

Answer 18

Nuclei which have too many of either protons or neutrons or both.

Question 19

How do nuclei with too many nucleons decay?

Answer 19

Alpha Decay

Question 20

How do nuclei with too many neutrons decay

Answer 20

Beta minus decay in which a neutron decays to a proton by the weak interaction

Question 21

What is meant by beta minus decay?

Answer 21

When a neutron turns into a proton, the atom releases an electron and an anti-electron neutrino

Question 22

What occurs when a particle and antiparticle meet?

Answer 22

Annihilation:

The mass of the particle and antiparticle is converted back to energy in the form of 2 gamma ray photons which go in opposite directions to conserve momentum.

Question 23

What is pair production?

Answer 23

A gamma ray photon is converted into a particle-antiparticle pair.

Question 24

The virtual photon is the exchange particle of which force?

Answer 24

The electromagnetic force.

Question 25

What type of particles are affected by the strong nuclear force?

Answer 25

Hadrons

Question 26

What is the exchange particle of the weak nuclear force?

Answer 26

The W boson (W+ or W-)

Question 27

Are electromagnetic waves transverse or longitudinal?

Answer 27

Transverse

Question 28

Describe the photoelectric effect.

Answer 28

When light above a particular frequency is shone on metal, electrons are released.

Question 29

Why does a photon need to be of a minimum frequency to liberate an electron?

Answer 29

THe energy of the photon is determined by its frequency, the photon’s energy must be greater than the work function in order for an electron to be emitted.

Question 30

What is meant by an ohmic conductor?

Answer 30

A conductor that obeys Ohm’s law, meaning that current is directly proportional to potential difference providing physical conditions (such as temperature) remain constant.