Energy and electricity Flashcards
What are the 8 energy stores?
Thermal Kinetic gravitational potential elastic potential chemical magnetic electrostatic nuclear
Give two methods of energy transfer
Mechanically and electrically
How does the way energy is stored change when someone throws a ball upwards?
Energy transferred from the chemical energy store the persons arm to the kinetic energy stores of the arm and the ball once the ball with release energy is transferred from kinetic energy store the board to its gravitational potential gravity energy store
Which has more energy in its kinetic energy store a person walking at 3 mph or a lorry travelling at 60 mph
I Lorry travelling at 60 mph
What is specific heat capacity
Specific heat capacity of the amount of energy needed to raise the temperature of 1 kg of the substance by 1°C
What is the conservation of energy principle
Energy can be transferred usefully stored or dissipated but can never be created or destroyed
What is conduction
Conduction is the process where vibrating particles transfer energy to neighbouring particles
What is convection
Convection is where energetic particles move away from the hotter to cooler regions
What is Power stage units is measured in
Power is the rate of doing work the units are watts
Give one where you could use the frictional forces in the hinge of an automatic door
Lubrication
For a given material how does it thermal conductivity affect the rate of energy transfer through it
The higher the rate of thermoconductivity the greater the rate of energy transfer through it
Why is the efficiency of an appliance always less than 100%
Some of the energy is always dissipated so less than 100% of the input energy transfer transferred usefully
Name three nonrenewable energy sources
Coal oil and natural gas
Give one advantage and one disadvantage associated with the reliability of renewable resources
Will never run out and energy output often can’t respond to immediate increases of energy demand
Give two ways in which student cold and energy resource can cause environmental problems
It releases greenhouse gases and contributes to global warming causes acid rain
Suggest two reasons why we can’t just stop using fossil fuels immediately
Renewable resaws is don’t currently provide enough energy and energy from honourable resources cannot be relied on upon currently
What are the units for resistance
Ohms
How does the current through a component vary with resistance for a fixed potential difference
The greater the resistance of the smaller the current Small of the resistance the greater the current
Give an example of an Ohmic conductor
A wire/ resistor
How should a voltmeter be connected in a circuit to measure the potential difference across the component
Across
What is an I-V characteristic
A graph that shows how the current flowing through a component change it as potential difference across it varies
One use of a light dependent resistor
Automatic night lights/ burglar detector
What happened to the resistance of a thermistor as the temperature increases
The resistance decreases
Give. One practical disadvantage of series circuits
You can’t switch components on and off independently
How do you work out the total resistance in a series circuit
Total resistance of the sum of all resistances
Which has the higher total resistance to resistors in a series all the same to resistors in parallel
Two resistors connected in series
Name the three wires in a three core cable that connects electrical appliances to the mains supply
Livewire neutral wire and earth wire
What is the main energy transfer one electric current flows through an electric kettle
Energy is transferred electronically to the thermal energy store of the heating element
What is the National Grid
Network of cables and Transformers that distributes electricity across the country
Define current
Flow of charge
What is meant by potential difference and resistance in the circuit
Potential difference is the driving force that pushes the charge around and resistance is anything in a circuit that slows the flow down
What is an Ohmic conductor
It obeys ohms law and has a constant resistance at a constant temperature and current flowing through the conductor is directly proportional to the potential difference across it
Name one linear component and one non-linear components
A resistor is linear and a diodes is non-linear
Explain how the resistance of an LDR varies with light intensity
As it gets darker resistance increases as it gets lighter resistance decreases
What happens to the resistance of a thermistor as it gets colder
As it gets colder resistance increases
True or false potential difference is shared between components in a series circuit
True
True or false the potential difference across each component connected in a parallel is different
False
Explain why adding resistors in parallel decreases the total resistance of the circuit but adding them on a series increase of the total resistance
Potential difference is the same everywhere is a parallel circuit which means the current flow is the same as the potential difference for every resistor you add but by adding another loop current has more directions to go in which increases current and decreases resistance. However in series the PD across each resistor is lower so the current through each resistor is also lower and current is the same everywhere so current is reduced when a resistor is added this means total resistance increases
True or false? Mains supply electricity is an alternating current
True
What is the potential difference and the frequency of the uk mains supply
230V and 50Hz
Name and give the colours of the three wires in a three core cable
Live-brown
Neutral-blue
Earth-yellow and green
Explain why touching a live wire is dangerous
You would get an electric shock which means current will flow through you
What is the power rating of an appliance
Shows the power it consumes
Explain why electricity is transferred by the national grid at high PD but low current
Less waste energy
What are the functions of a step up and a step down transformers
Potential difference is increased using a step up transformer for high demand and reduced by step down transformers
What is a system
A single object
Describe the energy transfers that occur when a car collided with a stationary object
The object does the work as it causes energy to be transferred from the car’s kinetic energy store to other energy stores
If energy is transferred to an object’s kinetic energy store what happens to the speed
Slows down
What kind of energy store is energy transferred to when you compress a string
Elastic potential energy
Which does he variable ‘e’ stand for in the equation for energy in elastic potential energy store
Elastic potential energy
What is the definition of the specific heat capacity of a material
The amount of energy required to raise the temperature of 1kg of a substance by 1 (degree Celsius)
Suggest why a material with a high specific heat capacity is better suited for use in a heating system than a material with a low specific heat capacity
It absorbs heat and raises heat quicker
True or false? Energy can be destroyed
False
How much energy is transferred per second to a 50W device
50J
True or false? A high thermal conductivity means there is a high rate of energy transfer
True
How can you reduce unwanted energy transfers in a machine with moving components
Insulating or lubricating
Give four ways to prevent unwanted energy transfers in the home
Loft insulation cavity walls double glazed windows and draught excluders
True or false thicker walls cool down a house quicker
False because thicker walls lower the rate of thermal conductivity and therefore the rate of energy transfer
Name four renewable energy resources
Wind,hydro,solar and nuclear
What’s the difference between renewable and non renewable
Renewable has a constant supply and non renewable cannot be made again
Give an example of how a renewable energy resource is used in every day life
Electricity in houses supplies by gas and oil
Explain why solar power is considered to be a fairly reliable energy resource
It’s a reliable source but only during day time
Give one environmental impact of using wave power to generate electricity
Causes flooding and loss of habitat
