Specific Heat Capacity

• What are the variables?

  1. Independent variable - Type of material  
  2. Dependent variable - Temperature rise
  3. Control variables - Mass of material, surface area of material
• Who is presenting the practical on measuring specific heat capacity?


  Mr. Reese
• What three materials are used in the specific heat capacity experiment?


  Brass, copper, and aluminium
• Why is it important to have water in the setup before taking measurements?

  To prevent an air gap between the metal and the thermometer for accurate readings
• What is the duration for which the temperature is recorded during the experiment?


  10 minutes
• What is the initial temperature recorded before starting the experiment?


  24 degrees Celsius
• What is the equation for specific heat capacity?


  Energy transferred = mass × specific heat capacity × temperature change
• How is specific heat capacity (shc) rearranged from the original equation?


  shc = energy / (mass × temperature change)
• What are the units of specific heat capacity (shc)?

  Joules per kilogram per degree Celsius
• Why does the block warm up slowly at the beginning of the experiment?

  Because the heater must heat up before it can heat the block at a steady rate
• What is the mass of the specially made blocks used in the experiment?

  1 kilogram
• How is energy calculated in this experiment?


  Using power
• How many flashes did the dual meter show in 30 seconds during the experiment?


  19 flashes
• How do you calculate the energy transferred based on the dual meter's readings?


  Energy = flashes × 100 joules
• What is the calculated power using the dual meter's readings?

  63 joules per second
• Why is the dual meter method considered less accurate?


  Because it measures power going into the power supply, not all of which goes into the heater
• How is the more accurate power measurement obtained?

  By multiplying the current flowing through the heater by the potential difference across it
• What is the current measured during the experiment?

  1. 47 amps
• What is the calculated power using the current and voltage readings?


  34.7 watts
• What should be plotted on the y-axis and x-axis of the results graph?

  Temperature on the y-axis and time on the x-axis
• How do you calculate specific heat capacity from the graph?


  shc = (power × time) / (mass × temperature change)
• What is the specific heat capacity calculated in the experiment?


  1050 joules per kilogram per degree Celsius
• What is the actual specific heat capacity for aluminium?


  900 joules per kilogram per degree Celsius
• Why is the calculated specific heat capacity higher than the actual value?


  Because energy is lost to the surroundings due to lack of insulation
• How can the accuracy of the experiment be improved?

  By insulating the block with foam
• What are the steps to measure specific heat capacity in the experiment?


  1. Set up the heater and thermometer in the block.
  2. Ensure water is present to avoid air gaps.
  3. Turn on the heater and record temperature every minute for 10 minutes.
  4. Measure power using a dual meter or voltmeter and ammeter.
  5. Plot temperature vs. time on a graph.
  6. Calculate specific heat capacity using the rearranged equation.
• What are the strengths and weaknesses of using a dual meter versus a voltmeter and ammeter for measuring power?


  Strengths of dual meter:

  • Easy to use
  • Quick readings

  
  

  Weaknesses of dual meter:

  • Less accurate
  • Measures power input, not output

  
  

  Strengths of voltmeter and ammeter:

  • More accurate power measurement
  • Directly measures current and voltage

  
  

  Weaknesses of voltmeter and ammeter:

  • More complex setup
  • Requires additional equipment