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• | specific heat capacity

  1. record mass of cylinder using a balance
  2. wrap cylinder with insulation to improve reliability
  3. Heat with electric heater
  4. Record energy transferred with joulemeter
  5. Record temperature change using stopwatch & thermometer
  6. plot on graph
  7. calculate temp change
  8. use equation for specific heat capacity
• | specific heat capacity

  • energy required to heat 1kg by 1 degrees Celsius
• | specific heat capacity

  • large heat capacity = more energy needed to get warmer; warms SLOWLY
• • small heat capacity means it can warm up quickly
• | I-V graphs

  • I = current
  • v= voltage / Potential difference
• | I-V graphs

  • lower gradient = HIGHER resistance
• | I-V graphs

  • constant resistances
• | I-V graphs

  1. set up standard test circuit with cell, ammeter (series), voltmeter (parallel to component) & variable resistor
  2. record current w/ ammeter
  3. record voltage with voltmeter
  4. adjust variable resistor to adjust current
  5. Repeat reading current & voltage and adjusting current to get multiple readings
  6. rotate & repeat to see how current flows in the other direction
• | I-V graphs

  
• | ohmic conductor

  • CONSTANT resistance in both directions

  
• | filament lamp

  • resistance Increases at high voltages
  • High voltages = flatter curve
  • flattening curve means lamp gets hotter

  
• | diode

  • one side is flat & other side gets steeper
  • current only passed in 1 direction
  • one side has high resistance so current can’t pass through

  
• | wires

  • neutral = blue wire
  • green = earth wire
  • brown = live wire
  • fuse

  
• | wires

  • live wire: brings current INTO appliance_ 230V & 50Hz
  • neutral wire: takes current AWAY from appliance to complete the circuit_ 0V
  • earth: removes excess current when appliance is faulty_ 0V
  • fuse: limits current flowing through brown wire

  
• | earth wire & fuse

  • earth wire always touches casing
  • with a fault, appliance can become LIVE & give electrical shocks

  1. resistance of appliance increases & stops current
  2. Fuse blows & stops current
  3. earth wire takes away current
• | investigating resistance

  • longer wire = more resistance!!!!
• | investigating resistance

  • cell, wire, crocodile clips, ruler, ammeter, voltmeter (parallel to clips), switch

  1. set clips next to each other
  2. voltmeter parallel & ammeter in series
  3. turn on switch
  4. calculate resistance (V/I)
  5. Move clips apart
  6. repeat 4-7
  7. plot a graph
  8. independent variable = length of wire (changing) & dependent= resistance (measuring)
• • systematic error / zero error if IV graph doesn’t start at 0
  • clips weren’t close enough
• | investigating resistance

  • constant: wire thickness_ Temperature: leave switch open so wires can cool
  • Hazards: high current & burnt skin- use low current
• | radioactivity

  • large nucleus = unstable
• | radioactivity

  • large nuclei will break down into smaller & stable nuclei by radioactive decay
  • releases gamma, beta & alpha
• | alpha

  • +2
  • HIGH ionising power
  • LOW penetration
  • blocked by paper or skin
• | beta

  • e-
  • Medium ionising power
  • Medium penetration
  • blocked by aluminium sheet
• | gamma

  • LOW ionising power
  • High penetration
  • stops at concrete or lead
• ionising: able to knock off ELECTRONS
• • alpha pulls electron off
  • Beta repels
  • gamma is absorbed
• | beta decay

  • neutron turns into proton, releasing an electron
• | heating curve

  • diagonal (/) & flat bits
  • Diagonal= energy is used to change temperature but not break bonds = specific heat capacity
  • flat = breaks bonds but not change temperature (specific latent heat)
• liquid -> gas = vaporisation
• specific latent heat = E = m x L (J/°C)
• | LDRS & thermistors

  • LDR depends on light
• LDR is an automatic switch
• LDR has low resistance when its bright
• LDR has high resistance when it’s dark
• thermistor changes on resistance on temperature
• When hot, low resistance - when cold, high resistance in thermistor
• circuits with LDRs & thermistors are called SENSING CIRCUITS
• what are circuits called with thermistors or LDRs?

  sensing circuits
• what are circuits called with thermistors or LDRs?

  sensing circuits
• series share voltage