P1 Flashcards
What did Dalton’s model of the atom look like?
A very small indestructible sphere
What subatomic particle did Thomson discover?
The electron
What did Thomson’s model of the atom look like?
Also known as the plum-pudding model
He thought it looked like a positive mass with negative electrons in it
Explain the experiment Rutherford conducted
He shot positively charged alpha particles at fixed gold metal foil
It was done in an evacuated chamber to prevent air molecules from absorbing the alpha particles
A detector, made from a microscope, was used to observe the experiment. Each time an alpha particle hit the plate, you would see a spot of light.
Explain what was expected to happen, and what actually happened in Rutherford’s experiment, and why
Rutherford expected all of the alpha particles to go through the foil, and most did, but some bounced back
Rutherford, therefore, discovered that atoms had tiny positively charged nuclei
When the positively charged alpha particles would come near to a positively charged nucleus, it would repel, as like charges repel
What does Rutherford’s model look like?
A simplified version of what we have today
What did Bohr suggest was wrong with Rutherford’s model? What did he add?
Bohr suggested that if the electrons just kept spiralling the nucleus, eventually the two would crash
He suggested that electrons orbited in fixed orbits called electron shells
What does density tell you?
How much mass there is in a certain volume
What is the density equation?
Density(kg/m3)=mass(kg)/volume(m3)
What is the densest state of matter? Why?
Solid is the densest state of matter, as in 1cm3 of a substance in the solid-state, there are more particles than those present in a liquid or gas
What does temperature tell you?
The average kinetic energy of the particles
How do you convert degrees into kelvin?
degrees->kelvin=+273
kelvin-degrees=-273
What does energy depend on?
The arrangement of the particles and how fast they are moving
What is specific heat capacity?
The energy needed to raise the temperature of 1kg of a material by 1 kelvin
What is the change from solid to gas and gas to solid called?
solid->gas= subliming gas->solid= depositing
What are the two types of latent heat?
Specific latent heat of fusion
Specific latent heat of vaporization
What is specific latent heat of fusion?
The energy transferred when 1kg of a substance goes from a solid to liquid and vice versa
What is the specific latent heat of vaporization?
The energy transferred when 1kg of a substance goes from liquid to gas
What happens to gas pressure as you increase the temperature?
If you increase the temperature, the particles in the gas move faster
This means more often collisions with the surfaces of the container
This means the gas pressure also increases
What is gas pressure recorded in?
Pascals (Pa)
What is the relationship between Pressure and Volume?
The particles in the gas bounce off the container walls at 90 degrees
If the volume is halved, there would be more collisions with the walls, meaning the pressure is doubled
Pressure and Volume are inversely proportional
What is the atmosphere?
A single layer of gas that covers the Earth and protects it
What is atmospheric pressure?
The pressure exerted by gases in the atmosphere
What happens to atmospheric pressure as you go up?
It decreases, as there is less and less air pushing you down from above
What is the gravitational field strength on earth?
10N/Kg
What equation do you use to find the depth at which something floats
Weight/ density X GFS X area
What is a vector quantity? Give an example
A quantity that is measured with a direction and a magnitude, e.g force
What is a scalar quantity?
A quantity that is measured with only a magnitude
Why are speed and velocity different?
Velocity is a vector, as you can measure it as 15m/s south
Speed is a scalar quantity
What is acceleration?
The change in velocity per second
What is the equation for acceleration?
Final velocity- initial velocity / time
What is the equation of motion?
FV^2-IV^2= 2 X acceleration X Distance
FV=Final Velocity
IV= Initial Velocity
What is the equation for kinetic energy?
kinetic energy (J) = 0.5 X mass (kg) X speed (m/s)
What is newton’s third law?
For every action, there is an equal and opposite reaction
What are non-contact forces? Give examples
Non- contact forces are forces that don’t need to touch each other to act. Examples include electrostatics, magnetism and gravity
What is a free body diagram
A diagram that shows the forces acting on a single object
What is the resultant force?
The total or overall force on an object
What is Newton’s First Law?
An object will continue to stay at rest or move with uniform velocity until a force acts on it
What is equilibrium?
If the resultant force equals zero
What is the resultant force of an object moving at a steady speed
Zero, as both forces are the same because the object is moving at a steady speed, meaning it isn’t accelerating or decelerating
What is the formula for force?
force (N) = Mass X acceleration
What does Newton’s Second Law state?
It states that the acceleration that the resultant force produces on an object depends on
The size of the resultant force
The mass of the object
What is terminal velocity?
When the force of air on something equals the force of Earth on it
What is the equation for momentum?
Momentum (kg m/s)= mass (kg) X velocity
What type of quantity is momentum?
It’s a vector quantity
What is the Law of Conservation of Momentum?
In any collision so the momentum before is equal to the momentum afterwards
What is the equation for Work Done?
Work done (j) = force (N) X distance (m)
What is doing work in science?
Using forces to transfer energy between stores
What does power tell you in science?
The rate at which energy is transferred
What is the equation of Power
Power (W) = Work done (J) / time (s)
What are plastic materials in science?
When the materials strech but don’t return to their original shape
What is the point is called at which force and extension no longer have a linear relationship?
Limit of Proportionality
What is the relationship between the extension of a spring and a force?
They have a direct proportionality
What is the equation for force exerted on a spring?
Force exerted by spring (N) = Spring constant (N/m) X extension (m)
What is a gravitational field?
A region where a mass experiences an attractive force
What is the equation for gravity?
Gravity= mass (kg) X GFS
What is weight?
Weight is the force of Earth on an object when it’s on the Earth’s surface l
Why is weight relative?
It’s because weight (N) = Mass (kg) X GFS and the Gravitational Field Strength on different planets aren’t the same
What is gravitational potential energy?
When energy is transferred to a gravity store
What equation is used to calculate gravitational potential energy?
GPE (j) = mass X height X gfs (N/kg)
How do you calculate the moment of a force?
Moment (Nm) = Force (N) X distance (m)
What is the equation for pressure, including force
Pressure= force / area
What happens when you rub two insulators together?
You transfer electrons from one insulator to another.
What is the equation for charge flow?
Charge flow (C) = current (A) X Time (s)
What is a permanent magnet?
A magnet that always causes a force on other magnets
What are two main features of a permanent magnet?
It produces its own magnetic field
The magnetic field cannot be turned on and off
How are induced and permanent magnet different?
A permanent magnet’s domain all line up, but an induced magnets only line up when there in a magnetic field
How can you test if something is a permanent or induced magnets?
Permanent magnets repel when two of the same poles are places together, induced magnets don’t
What does the dot and Cross show on a magnetic field of a wire?
The dot shows that the wire is coming out of the paper, the cross shows that the wire is going in the paper
What is a solenoid and how does it work?
A solenoid consists of a wire spun around in a spiral shape
When a current passes through the wire, each makes its own individual magnetic field that join together to make one large uniform magnetic field
What can you change in a solenoid to make it stronger?
increasing the number of turns on the coil
increasing the current
placing an iron core inside the solenoid
What is the catapult effect?
When a wire, creating magnetic field, interrups a magnet, creating another magnetic field, and the wire is then pushes out of the magnetic field
What does each finger show for Fleming left hand rule?
ThuMb-Movement
First Finger- Field
SeCond Finger - Current
Why would a motor not work without a split ring commutator?
It wouldn’t work as when the wire gets in the vertical position, the wire’s magnetic field would be parallel to the magnets meaning there would be no force
What does the split ring commutator do every half turn?
It changes the current direction, meaning the magnetic field is now the other way, and is no longer parallel to the magnet’s magnetic field
What happens when a magnet is still inside a coil of wire?
There is no movement between the magnetic field and the conductor, so there is no induced voltage and therefore no induced current is made
How can you increase the induced voltage made in electromagnetic induction?
Moving the wire/ magnet faster
Using a stronger magnetic field
Using more wire
What is an ac generator and how does it work?
An AC generator is a generator that induces alternating potential difference. It is a coil of wire that is placed in a magnetic field, and is therefore spun around if current is supplied. It doesn’t need a split ring commutator, as the coils of wire(conductor) is turned by the magnet (magnetic field) creating induced voltage
How do the brushes help in an AC generator?
The brushes aren’t attached to the slip rings. They are made of conductors that carry the output voltage into the circuit by brushing against the split rings. They also help the wire’s not get tangled
What is a dynamo?
A DC generator. The potential difference produced in this generator doesn’t alternate, and is always positive
What is a transformer?
A device that can increase or decrease the potential difference
What is the structure of a transformer?
A primary coil from the ac input, a secondary coil from the ac output, wound around an iron core
How does a transformer work?
The coils around the primary core creates a magnetic field due to the alternating current flowing through the wire
The iron core increases the strength of the magnetic field
This induces a changing pd in the secondary coil that makes an alternating current
What is the equation for transformers
Voltage across PC/ Voltage across SC = No of turns in PC/ No of turns in SC
