FWAQ Flashcards
(17 cards)
What is meant by the term half life
The time taken for the half the radioactivity to decay
Explain the stage of a falling object
Object is accelerating
downward force is greater than upward force
Forces are unbalanced
There is resultant force
As the upward force increases so does the downward force
Resultant force decreases
forces become balanced
resultant force is to equal to zero
terminal velocity is achieved
Describe the relationship between temperature and resistance ( reference to graph)
As temperature increases the resistance of the thermistor decreases
current increases
non- linear graph
what are the conditions for nuclear fusion to occur in a core star
Very high temperature
Very high pressures
very high kinetic energy
to overcome electrostatic repulsion
what is the human hearing range
20-20000 Hz
What are advantages and disadvantages of hydroelectricity
Advantage
- doesn’t take up too much land
- not weather dependant
Disadvantage
- can cause floods in large areas
- Expensive to build
requires a large dam
- installation is permanent
Describe the energy transfer that are involved in generating electricity in a hydroelectric power station
Reduction in GPE store of water
mechanical work done on turbine
increase in KE store of turbine
mechanical work done on generator
increase in KE store of generator
Mechanical work done on generator
Increase in KE store of generator
Idea of electrical work done on grid
Explain how red- shift galaxies supports the big bang theory
The further the galaxy is from earth the greater the red shift
The greater the red-shift, the faster the galaxy is moving away
Speed of the galaxies increases with increased distance
The speed and distance are directly proportional
Relationship between speed and distance implies expansion
expansion implies there was a single point in the past
Name a fuel used in the reactor of a nuclear Power station
Uranium
Describe the process of Nuclear fission
A nucleus absorbs a neutron
The nucleus formed splits because it is unstable
The nucleus splits into two smaller nuclei called daughter
nuclei and two or three neutrons
The energy released is transferred into the kinetic energy store of the fission products
Describe how a main sequence star is formed from a nebula
Nebula is cloud of dust and gas
Gravity causes cloud to collapse
temperature of cloud increases creating protostar
Temperatures reach high enough in main sequenced hydrogen fusion starts
Describe how a main sequence star becomes a white dwarf
Hydrogen fusion runs out in core
core collapses
Core temperature of star increases
Star expands to become a red giant
Surface temperature of star decreases
helium fusion begins
White dwarf formed when helium fusion in core runs out
Rest of star released as planetary nebula
Describe an experiment to determine the refractive index of a glass block
Apparatus
- light ray box
-protractor
Method
- Draw around glass box
- Shine ray light onto the block at an angle to the normal
- Mark incident and refracted rays
measure the angles from normal
- Repeat for different angles of incidence and calculate an average
Use sin (i)/ sin(r)= n (refractive index)
or plot graph of sin (i) aganist sin (r)
gradient equals Refractive index (N)
Give two uses for total internal reflection
Optical fibres
Binoculars
Explain how the box is designed to reduce energy trasnfer by conduction
Using cardboard ( poor conductor)
Air is gas
Particles in air are far apart
collide with each other rarely
Explain how the box is designed to reduce energy transfer
No air gaps ( air particles cannot move)
lid stops or reduces a convection current forming
what is a critical angle
Angle of incidence in the slower medium above which total internal reflection occurs
