Physics - 2 Energy Transfer by Heating - Required Practical 1: Specific Heat Capacity

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Aims:

  • find the specific heat capacity of a metal block or of water

Risk Assessment:

  • hot water can splash up into eyes/heater can come into contact with eyes

  • water around electricity can be dangerous

  • the heating equipment can burn you

Safety:

  • always wear eye protection

  • dry hands and clean up any spills around electrical appliances

  • be careful not to touch the heater or the hot water

Equipment:

  • copper block with 2 holes

  • aluminium block with 2 holes

  • 250cmÂł beaker

  • water

  • petroleum jelly

  • 50 W, 12 V heater

  • 12V power supply

  • insulation

  • ammeter

  • voltmeter

  • 5 leads

  • stopwatch

  • balance (mass)

  • eye protection

Control variables:

  • temperature of surroundings

  • voltage from power pack

Independent variable:

  • temperature of the heater

Dependent variable:

  • rate of increase in temperature of the block/water

Method:

  1. Measure the mass (in kg) of the block/water using a balance

  2. Wrap the block/beaker in insulation

  3. (If block) Smear bulb end of thermometer with petroleum jelly and insert into block

  4. Measure starting temperature of block

  5. Connect the power pack, heater and ammeter in series, and the voltmeter in parallel over the power pack

  6. Insert the heater into the block/water and switch on. Simultaneously start stopwatch

  7. For a total of 10 minutes, record the current (ammeter), potential difference (voltmeter) and temperature (thermometer) every 60 seconds

  8. Turn the power pack off. Wait a while longer and record the maximum temperature of the block/water

Calculations & graphing:

  • Find the power every 60 seconds with P = IV

  • Find the energy transferred every 60 seconds with E = Pt

  • Graph temperature change (y-axis) against energy transferred (x-axis)

  • Find SHC from graph using c = 1/(m x gradient)