Nuclear physics- Reactions and radioactivity

Question 1

Continuous spectrum

Answer 1

a spectrum in which light is spread smoothly over a broad band of wavelengths (or frequencies). A piece of hot metal produces a continuous spectrum.

Question 2

Line spectrum

Answer 2

a spectrum in which the defining features are sharp lines (spectral lines) at discrete wavelengths (or frequencies), against an otherwise continuous background.

Question 3

emission spectrum

Answer 3

line spectrum in which discrete bright lines are set against a dark background. A hot gas produces an emission spectrum.

Question 4

Absorption spectrum

Answer 4

a line spectrum in which discrete dark lines are set against an otherwise continuous spectrum. A cold gas illuminated by a continuous spectral source leads to an absorption spectrum.

Question 5

What is Planck’s formula- Calculate the total energy in a photon

Answer 5

E=hf
h=Planck’s constant
f=frequency

Question 6

What is the general trend of the hydrogen emission spectrum

Answer 6

If it goes to n=1. then it is UV
If it goes to n=2, it is visible
If it goes to n=3, it is Infrared

Question 7

Define radioactivity

Answer 7

he emission of ionising radiation as a result of changes to the nuclear energy of a radionuclide.

Question 8

What is emitted in Alpha decay

Answer 8

Alpha particles, or helium nuclei

Question 9

What is emitted in Beta minus decay

Answer 9

electron and antineutrino

Question 10

What is emitted in gamma decay

Answer 10

Gamma radiation as a result of an oscillating nucleus. There is no transmutation(change in atomic or charge)

Question 11

What ensures the most stable nucleus?

How does the type of radiation achieve this?

Answer 11

When the number of neutrons=protons
When it’s more protons- Beta minus
More neutrons-Beta minus

Question 12

What is the penetrating power of A, B plus and gamma

Answer 12

A- weak: few cm in air, stopped by card
B- 1 metre in air, stopped by 5 mm aluminium
gamma- at least one km in air, stopped by 10 cm lead

Question 13

How would you see what kind of radiation something is undergoing?

Answer 13

place the source between charged plates, see where it goes

Question 14

Define activity

Answer 14

The number of radioactive decays per second

Question 15

What is the rate of decay proportional to

Answer 15

Rate of decay of N radionuclides is proportional to the negative number of radionuclides

Question 16

What is mass defect/binding energy

Answer 16

The mass of the individual nucleons minus the mass of the nucleus: The individual masses added together will exceed that of the nucleus, as the mass is lost as energy.

The binding energy is the energy equivalent of the mass defect

Question 17

Sketch the curve of avg binding energy per nucleon against atomic number.

Answer 17

Shape is like a negative exponential, with a peak at NICKEL, and a small peak at Helium

Question 18

What is difference between fusion and fission

Which way does the proton number go?

Answer 18

Fusion- nucleus join. Occurs when proton number is less than nickel.

Fission-Atom splitting into two daughter nuclei. Occurs when larger number than Nickel

Question 19

Two ways to calculate energy released in fission and fusion?

Answer 19

1. Binding energy difference

2. calculate the mass difference, then convert to energy