Physics paper 1 Flashcards
What is the law of conservation of energy?
Energy is always conserved- it cannot be created or destroyed
What is energy measured in?
Joules
What is sound/ vibrational energy?
Kinetic energy
What 3 things contain chemical potential energy?
Fuels, food and cells
What specific heat capacity?
The energy needed to raise the temperature of 1kg of a substance by 1’C
What is a system?
When objects interact and energy is transferred from one store to another.
How is energy transferred if an object falls?
GPE is transferred to Kinetic Energy
What is a feature of a closed system?
No energy is transferred to/from the surroundings
What is the specific heat capacity?(practical)
measure mass of water in beaker
place electrical heater in water
measure initial temperature of substance using thermometer
turn heater on, start timer and measure p.d. and current supplied to the heater using voltmeter and ammeter
After set time, measure final temp and calculate change in temperature.
Calculate SHC
What is power?
The rate of energy transfer
What is efficiency?
The proportion of total input energy that is converted to useful output energy
What are energy sources?
Where we harness energy from in the world
What examples of finite sources?
Nuclear fuel
Fossil fuels (Coal, oil and natural gas)
What are examples of renewable sources?
Wind power
Hydroelectric
Solar power
geothermal
What does a cell do?
Supply energy to electrons, which then move through wires to transfer energy
What direction does charge always flow from?
Positive to negative
What is potential difference?
The measure of how much energy is transferred to each coulomb of charge.
What is potential difference measured in?
Volts
What is current?
The rate of flow of charge
What is current measured in?
Amps
How are ammeters connected in a circuit?
In series with components
How are voltmeters connected in a circuit?
In parallel with components
What is resistance?
the measure of how much a component resists the flow of current.
What unit is resistance measured in?
Ohms
What is Ohm’s law?
P.D. = current * resistance
How is resistance calculated from an I-V graph?
By pick a point on the line and rearranging ohm’s law.
NEVER draw a tangent.
How do you draw an I-V graph for a fixed resistor?
Straight line through origin: V and I are directly proportional
How do you draw an I-V graph for a filament lamp?
The line curves: resistance NOT constant
This due to delocalised electrons colliding with ionic lattice and vibrating more
Larger current = increased resistance (non-ohmic)