p1 Energy Flashcards
What is conduction?
when heat moves from one object to another object through direct touch
What is dissipated energy?
Energy that is transferred to the environment so that it can no longer be usefully transferred
What is efficiency?
How much energy is usefully transferred by an appliance
What is energy transfer?
When energy is moved from one energy store to another
What is the gravitational field strength?
The pull of the force of gravity on each kg of mass.
What is insulation?
A material that reduced energy transfers to or from a system
What is kinetic energy?
The energy stored in an object that is moving
What is a lubricant?
A substance added to surfaces to reduce the amount of friction (oil)
What is a non renewable source?
A resource that is not replaced as it is used
What is power?
The rate at which energy is transferred or the rate at which work is done
What is a renewable resource?
A resource that is replenished as it is used
What is specific heat capacity?
The amount of energy needed to raise the temperature of 1kg of a material by 1 degrees celsius
What is watt?
A unit of power
1 watt= 1 joule transferred per sec
What is work done,
The energy transferred when a force moves
Where are electric fields found?
Around all charged objects
What two characteristics affect the strength of the field?
-The closer u get the stronger the field
- the closer the lines the stronger the field
Describe the electric field around a positively charged sphere
- Field lines travel from positive to negative
- further away= weaker the field because field lines move further apart
What do field lines always go from?
Positive to negative
Explain sparking in terms of electric fields. (5 marks)
- high pd causes a strong electric field
- electrons in the air particles are removed (ionisation)
- ionised air can conduct
- current flows through it
- this is the spark
What is ionisation?
When an atom or molecule either loses or gains electrons which makes it charged.
If an atom or molecule gains electrons does it become positively charged or negatively charged?
Negatively charged= anion
If an atom or molecule loses electrons does it become positively charged or negatively charged?- WHATS the scientific word
Positively charged= cation
What is specific heat capacity?
The amount of energy needed to change the temperature of 1kg of a substance by 1 degrees Celsius
The specific heat capacity equation tells us that the temperature change of a substance depends on three things. Name them.
- mass of a substance (m)
- energy supplied
- specific heat capacity of the substance
What is the equation for specific heat capacity?
Energy= mass* specific heat capacity* temp change
In an IV graph experiment, what happens to the resistance of the filament lamp?
Resistance increases due to increased collisions between metal ions and delocalised electrons
What happens to the thermal store of the ions in a filament lamp?
Increases
What happens to the current when the potential difference is negative in the diode version of the IV graph experiment?
Almost no current flows
Describe the relationship between the potential difference and the current in the filament lamp?
As the pd increase the current increases BY A SMALLER AMOUNT
Describe the relationship of the resistance and the current in the filament lamp?
Resistance= increases
Current = decreases
What allows the current to flow in one direction in a diode?
Low resistance when potential difference is positive
What is the equipment used for the experiment on characteristics of pd and current of components (5)
- battery
- wires
-ammeter
-voltmeter - variable resistor
Describe the steps in investigating the current and pd characteristics of components.
1- use voltmeter to read the pd across resistor
2- use an ammeter to read the current through the resistor
3- record values in a table
4- adjust variable resistor and record both new readings
5- do this several times to get range of readings
6- switch direction of battery (pd reversed) + voltmeter and ammeter= negative values
7- continue taking several readings
8- plot graph of current against pd
What is an error that can be caused during the experiment of the fixed resistor?
If resistor too hot= temp increases instead of staying constant= graph will not be directly proportional
For the filament lamp, how would u continue the experiment?
1- replaced resistor with filament lamp
2- adjust variable resistor and read both pd and current
3- do this for a range of values with the battery in the forward and reverse direction
For the dioxide how would u continue the experiment?
-replace filament lamp with diode
- add an extra resistor (because diodes are very easily damaged by high current)
- current is low= we need a sensitive ammeter= milliammeter
- adjust the variable resistor a number of times and record the pd and current
- do this with the battery in the forward and reverse direction
In what case do we get a current in a diode? (Pd)
When the pd is around 0.6-0.7 volts
What happens to current if the potential difference increases from 0.6-0.7 volts?
Current rises sharply
In an experiment, the diode is shown to have no current, what is the reason behind this and why?
Potential difference is reversed because in the reverse direction a diode has a high resistance
What is the relationship between the light intensity and the resistance of an LDR?
Light intensity increases= resistance decreases
Describe why an LED night light does not work during the day?
- light intensity is high+ resistance is low
- loop with LDR has the lowest resistance
- most current flows through the LDR+ NOT LAMP
- lamp does not light
Explain how an LED night light manages to light at night.
- light intensity is low + resistance is high
- loop with lamp has the lowest resistance
- most current flows through lamp
- lamp lights up
What happens to the temps tire as insulation got thicker?
Temperature decreases less over the 20 mins
What are the 8 steps in investigating the change of temp from the thickness of insulation?
1- mark a mine on the outside of the beaker around the 200cm cubed mark
2- wrap the beaker in the insulating material
3- use kettle to boil water
4- pour hot water into the beaker up to the marker line
5- use a cardboard with a hole in for the large beaker (hole for thermometer
6- insert thermometer and leave for a minute to record starting temp
7- record temp of water every 5 mins up until 20 mins
What are three hazards in the insulation experiment and what are the three risks?
- hot water= scalds
- hot beaker= burns
- electricity and water= shock
