physics p1

• What is a closed system?

  A system where neither matter nor energy can enter or leave
• what is meant by work done?

  energy transferred in a system
• how is power different to work done?

  power is the rate of doing work
• what is SHC


  The amount of energy needed to raise the temperature of 1kg of a substance by 1°C
• how can heat transfer from a building be reduced?

  insulation, by reducing the rate energy trasfer
• how can energy loss due to friction be reduced?

  lubricant coat objects
• 8 energy stores


  chemical

  kinetic

  electrostatic

  nuclear

  elastic potential

  gravitational

  elastic

  magnetic
• What is the conservation of energy?

  Energy cannot be created or destroyed
• fossil fuels + and -

  + reliable

  * respond quicker to demand

  - impact global warming

  - not renewable
• nuclear fuels + and -

  + reliable

  + respond quick to demand

  - toxic to humans

  - not renewable
• biofuels + and -


  + renewable

  + carbon neutral

  - expensive

  - lots of land needed
• wind power + and -

  + renewable

  - use land

  - expensive

  - weather dependant
• hydroelectric power + and -

  + no pollutants

  + immediate response

  - flooding can cause loss of habitat

  - expensive
• what are most energy resources used for?

  transport and heating
• What is a renewable energy source?

  A source of energy that will never run out; it is limitless.
• 4 ways every can be transferred between stores

  mechanical

  chemical

  electrical

  heating
• what is needed for an electric charge to flow through a circuit?

  a closed circuit witha. potential difference
• what is electric current?

  The flow of electrical charge
• what does the current through a component depend on?

  resistance and potential difference
• How does an LDR work?

  As light intensity increases, resistance decreases
• how can LDRs be used?

  automatic night lights, burglar alarms
• h

  how does a thermistor work?

  as temperature increases, resistance decreases
• how can thermistors be used?

  car engine sensors, thermostats
• How is current measured?

  amps through an ammeter
• How is potential difference measured?

  volts through a voltmeter
• action of an ohmic conductor


  current and PD are directly proportional
• action of a filament lamp

  as current increases, so does temperature therefore resistance, so less current can flow per unit PD
• action of a diode

  current only flows in one direction and has a high resistance in the reverse direction
• describe current, pd and resistance in SERIES

  PD is shared

  Current is the same everywhere

  Resistance adds up
• describe current, pd and resistance in PARALLEL

  PD is the same across components

  Current is shared among branches

  Resistors reduce total resistance
• what is DC


  direct current, eg light switches
• what is AC


  alternating current, eg loudspeaker
• what is the frequency and PD in domestic electricity

  250V, 50Hz
• what cable do most domestic electric appliances use?

  earth
• how is static charge built up?

  insulating materials rubbing together
• action of charged objects

  attraction/ repulsion, force relative to distance
• what is an electric field?


  Area around electric charge
• what is the national grid?

  A giant system of cables and transformers that covers the UK and connects power stations to consumers
• what is the purpose of a step up transformer?

  increase voltage
• what is the purpose of a step down transformer?

  decrease voltage