Fields, Particles and Frontiers of Physics

Question 1

Activity

Answer 1

The number of radioactive decays per unit time. Measured in Becquerels (Bq)

Question 2

Electric Field Strength

Answer 2

Force per unit positive charge

Question 3

Magnetic Flux Density

Answer 3

A measure of the strength of the magnetic field as given by B= F/ILSin(x)

Question 4

Magnetic Field

Answer 4

A region in space where a magentic pole experiences a force. It goes from N to S

Question 5

Magnetic Field Strength

Answer 5

Another name for Magnetic Flux Density

Question 6

Magnetic Flux Linkage

Answer 6

The product of the magnetic flux and the number of turns on the coil it passes through. Given by N x Magnetic Flux.

Question 7

Unit of Magnetic Flux Linkage

Answer 7

Weber Turns

Question 8

Unit of Magnetic Flux Density

Answer 8

Tesla

Question 9

Unit of Magnetic Flux

Answer 9

Weber

Question 10

Tesla

Answer 10

1T is the magentic flux density that will produce a force of 1N on 1m of wire carrying a current of 1A perpendicular to the direction of the magnetic field.

Question 11

Lenz’s Law

Answer 11

The direction of any induced current is in the direction that opposes the flux change that causes it.

Question 12

Faraday’s Law

Answer 12

The magnitude of the induced e.m.f. is equal to the rate of change of flux linkage

Question 13

What is Flemings Left Hand rule used for?

Answer 13

Electric Motors

Question 14

What is Flemings Right Hand rule used for?

Answer 14

Generators and electromagnetic induction.

Question 15

Capacitance

Answer 15

The charge stored per unit potential difference, as given by C = Q/V

Question 16

Farad

Answer 16

1F is 1C of charge stored per volt

Question 17

Unit of Capacitance

Answer 17

Farad

Question 18

Time Constant

Answer 18

The time taken for the charge remaining on a capacitor to fall to 1/e of its original value. Found by CR, measured in seconds.

Question 19

Proton Number

Answer 19

The number of protons inside a certain nucleus. Also known as the atomic number.

Question 20

Nucleon Number

Answer 20

The number of neutrons added to the number of protons inside a certain nucleus. An alternative name for mass number.

Question 21

What are Pions and Kaons? (Family Tree)

Answer 21

Meson

Question 22

What is a Proton? (Family Tree)

Answer 22

Baryon

Question 23

What is a Neutron? (Family Tree)

Answer 23

Baryon

Question 24

What is an Electron? (Family Tree)

Answer 24

Lepton

Question 25

Charge of an Up Quark

Answer 25

+2/3

Question 26

Charge of a Down Quark

Answer 26

-1/3

Question 27

Baryon number of a Quark

Answer 27

+1/3

Question 28

Quark Structure of a Proton

Answer 28

uud

Question 29

Quark Structure of a Neutron

Answer 29

udd

Question 30

Fundamental Particle

Answer 30

A particle that cannot be broken down into smaller components (e.g Leptons)

Question 31

Isotopes

Answer 31

Nuclides with the same number of protons but different number of neutrons.

Question 32

B+ decay in terms of quarks

Answer 32

uud -> udd

Question 33

B- decay in terms of quarks

Answer 33

udd -> uud

Question 34

B+ decay produces which particles?

Answer 34

Electron-neutrino and positron

Question 35

B- decay produces which particles?

Answer 35

Electro-antineutrino and electron

Question 36

Decay Constant

Answer 36

The probability of radioactive decay given by lambda = A/N

Question 37

Unit of Decay Constant

Answer 37

s-1

Question 38

Half-life

Answer 38

The average time taken for the activity of a radioactive source to decrease to one half of its original value.

Question 39

Binding Energy

Answer 39

The energy required to separate an atom into its component parts

Question 40

Binding Energy per nucleon

Answer 40

The average energy required to remove a nucleon from the nucleus.

Question 41

Intensity

Answer 41

Power per unit cross sectional area.

Question 42

Compton Effect

Answer 42

The effect whereby X-rays are deflected off particles have a longer wavelength than their initial wavelength.

Question 43

Doppler effect

Answer 43

The change in wavelength caused by the relative motion between the wave source and an observer

Question 44

Piezoelectric effect

Answer 44

The change in volume of certain crystals when a p.d. is applied across them. Alternatively an emf is produced when certain crystals are placed under stress.

Question 45

Olbers Paradox

Answer 45

With an infinite amount of stars in an infinite universe, no matter what direction you look, you will always see a star along your line of sight. Therefore the night sky will be as bright as the day sky.

Question 46

Critical Density

Answer 46

The average density of the universe for which the universe will expand towards a finite limit which will result in a flat universe.

Question 47

Two assumptions of Olbers Paradox.

Answer 47

1) Universe is homogenous, 2) Universe is infinite

Question 48

Hubble's Law

Answer 48

The speed of recession of a galaxy is proportional to its | distance from Earth.