Physics hard questions

Use of infrared rays

Heating

Describe how energy is transferred by conduction through metal strips

• when a particle is heated it gains more kinetic energy

• so it collides with its neighbouring particles transferring its thermal energy through the structure

Doppler effect

• the oberver observes those waves at a smaller wave length

• wave speed stays the same

• so wave frequency increases

Read smth at the ____ of the meniscus

bottom

Activity

the rate at which unstable nuclei in a radioactive source decay

Unit for activity

Bq

Alpha particle

2 protons and 2 neutrons

Beta particle

high speed electron

gamma decay

a wave

background radiation sources

• radon gas

• cosmic rays

Count rate

the rate at which radioactive emissions are detected

count rate unit

counts per second / Bq

Half life

the time taken for the number of nuclei of a sample of radioactive isotopes to decrease by half

Power

The rate at which energy is transferred

Work done =

energy transferred

Hooke’s Law

the extension of an elastic object, like a spring, is directly proportional to the force applied to it, provided the object's limit of proportionality is not exceeded

Ways to increase conduction

• Big temperature difference

• Use materials with high conductivity

How to stop a convection current

Prevent a fluid from forming so eliminate the temperature difference

Use a lid to stop hot air from coming in as it would create a convection current

How to reduce conduction

• Have air trapped between layer and conduction can only happen in solids

• use insulating materials

What happens in beta decay

a neutron in an unstable nucleus turns into a proton and a high-energy electron (a beta particle), which is then ejected from the atom.

Chain reaction

When one neutron generated by the fission of one nucleus, goes on to cause the fission of another nucleus when it is absorbed by that nucleus. This will generate more neutrons and this process continues releasing large amounts of energy.

Nuclear fission

Nuclear fission is the splitting up of heavy nucleus into lighter ones when a neutron is absorbed. The products are two daughter nuclei ( which are usually radioactive) , several neutrons and lots of energy is released in the form of kinetic energy of the products.

 

Nuclear fusion

when two light nuclei join together to form a , heavier nucleus, releasing a large amount of energy in the process

Nuclear fusion requires

High temp and high pressure due to electrostatic repulsion of protons

As radius increases g gets…

smaller because gravity is more spread out

More mass then ___ g

bigger as theres stronger pull

nebula

a cloud of dust and gas

Stellar evolution for our sun star type

protostar, main sequence, red giant, white dwarf, black dwarf

stellar evolution for stars that ARE NOT the sun

protostar, main sequence star, red super giant, supernova, either neutron star or black hole

Control rods

to absorb neutrons, made of BORON

Moderator

Slows down neutrons→ heavy water or graphite

Point of shielding

to contain harmful radiation produced during nuclear fission, ensuring the safety of workers and the environment by blocking high-energy gamma rays and neutrons

What is shielding made of

concrete