very important things to remember for paper 2

What other value can you sub into the radioactive decay equation? 𝑁 = 𝑁oe^−t𝜆

Activity, A = Aoe^-λt

What is the general shape of a graph that has
Y axis - Binding energy per nucleon
X axis - Nucleon number

What should its peak value be?

Draw something like this, the peak being 8.7MeV

On which side of the peak does fission and fusion occur?

Right of the peak - Fission
Left of the peak - Fusion

Sketch a labelled diagram showing the experimental arrangement of the apparatus used by Rutherford.

If asked to determine a half-life from a graph, its better that you…

Take 2 readings and find an average half-life time

What does corrected count rate mean?

Activity - background activity

How can you ensure the measured count rate is accurate?

Take an average

If a question says ‘‘probability of decay’’ what is it actually referring to?

Decay constant

What is a sanity check you can do when working with a decay constant?

Its always a very small number, so if its not theres been an error in your working

If a question mentions a numerical amount for a background count rate, and later asks you to find a background rate, what MUST you make sure you remember to do

Add the background rate onto the calculated count rate

What material can stop Beta particles?

aluminum sheet

If asked to find the energy released from 2 nuclei fusing, what must you do? (2 things)

1. Find the difference in mass, then convert it into MeV using u

2. E = mc² often needed

In thermal physics, what is a useful equation to know regarding work done?

W = Q_shc + Q_slh

Give 4 assumptions made in deriving the kinetic theory model equation

1. All collisions are elastic

2. Volume of particles is negligible

3. Collision time is negligible compared to time between collisions

4. There are no forces between the particles except during collisions

Explain why molecules of gas exert a force on the walls of a container (2 points)

1. Change in velocity when it hits wall which means Newtons second law, as they have acceleration and mass so they have force

2. The force on the wall is equal to the force on the particle, Newtons third law

If V is kept constant, what effect does doubling Temperature have on Pressure?

Doubled

1. Electrons move to outer surface

2. Electrons are equally spaced because electrons mutually repel

What 2 things does closer spaced field lines indicate (gravitational)

1. Object has high mass

2. Field is strong

g = 0.4

Gravity will drop off by the square of the distance
0.4/1² = 0.4
0.4/0.2² = 0.1
0.4/0.3² = 0.04

What would the area underneath this graph represent?

Work done on the object per unit mass when moving from R to 2R

Find force between P and H which is1.8×10^13
Calculate the resultant force on P from both H and G acting on it
sqrt(6.38×10^12)² + (1.8×10^13)² = 1.9×10^13
Plug resultant force into F = ma to give 9.5×10^-8

When and only when is it possible for a planet to have a circular motion around another one

When the resultant force of that planet is acting towards the centre of the other

What is the function of a core in a transformer?

Enhances the magnetic flux linkage between the primary and secondary coils, improving the efficiency of energy transfer.

What is the function of the secondary coil in a transformer?

Has a varying magnetic flux or field passing through or linking with it, inducing an alternating current (AC).

What do the functions of the secondary coil and the core result in?

An induced EMF is made, and its magnitude is determined by the number of turns in the secondary coils

Why does the number of turns in the secondary coil determine the magnitude of the induced EMF produced?

Each turn increases the magnetic flux because the strength of the magnetic field increases and interacts with other field made by primary coil

Sheets M are insulators with high resistivity which will help reduce current flowing in the core

Thin sheets of iron are used because their resistance is high which will reduce currents

1. In order for power to remain the same but voltage to be low, current must be high which we dont want because energy will be lost, P = I²R

2. If the voltage is too high it will be difficult to insulate

Explain what is meant by the binding energy of a nucleus

Energy required to separate the nucleus into its constituent protons and neutrons

How do you convert Kg into MeV?

931.5/1.661×10^-27

They must add up to 240 nucleon number and cannot be above the peak

1. Fission fragments have a high Z/N ratio

2. The initial decay mode is B-

3. Neutron changes to proton which are more stable so graph moves closer to stable region

What are fission fragments and what property do they usually posses?

Smaller nuclei that have been separated from a larger nucleus during fission, have high Z/N ratios

If temperature of an ideal gas doubles, what 2 things should also double?

Internal energy and pressure

What is the equation for escape velocity?

sqrt(2gR)

What does dielectric constant mean?

permittivity of medium/permittivity of free space

1. Polar molecules align their positive side facing the negative plate

2. Reduces the electric field between the plates

3. V decreases but charge is the same, therefore capacitance increases because C = Q/V

Dielectric constant just means you multiply the capacitance by 6
E = ½ Q²/C
E = ½ Q²/6C
(4.58x10^-9) – (7.64x10^-10) = 3.8×10^-9

1. Decrease the plate separation to ¼ of their original

2. Use a dielectric metal with 4 times greater than original

What is the relationship between Area and Diameter

Area drops off with square of diameter

Why is it better for spacecraft to be launched from the equator?

At the equator the spin of the earth is at its greatest, therefore the craft will have its largest initial kinetic energy from Earths rotation

Why would the linear speed of a satellite in higher circular orbit be less than one in lower circular orbit?

v is inversely proportional to 1/sqrt(r)

Relationship between V and Q

Proportional, double one the other doubles

what is a dielectric and what does it do

insulating material inserted between the plates that increases the permeability which increases capacitance

explain what a cyclotron is used for and what it does

it produces a beam of protons by forcing them into circular motion inside the metal Dees using a magnetic field

How does the cyclotron ensure the protons increase their radius

Dees are opposite charged which causes the protons to be accelerated across the gap increasing their speed and therefore their radius

Faradays law

EMF induced is proportional to the rate of change of flux