Required Practical 1

Question 1

Describe the method for this experiment

Answer 1

1. Measure and record the mass of the copper block, in kg
2. Place a heater in the larger hole of the block. Connect the ammeter, power pack and heater in series
3. Connect the voltmeter across the power pack
4. Put a small amount of water in the other hole using a pipette and put the thermometer in this hole
5. Switch the power pack to 12V and turn it on
6. Record the ammeter and voltmeter readings. These shouldn’t change during the experiment
7. Measure the temperature and switch on the stop clock, record the temperature every minute for 10 minutes
8. Calculate the power of the heater in watts by multiplying the ammeter and voltmeter readings
9. Calculate the work done by the heater by multiplying the time in seconds and the power of the heater
   10.

Question 2

The experimental value of the specific heat capacity differs from the true value. Suggest one way the student could change the experiment to reduce this difference.

Answer 2

• Add insulation around the block
• This reduces the amount of energy lost to the surroundings, making their energy measurements more accurate
• So the specific heat capacity would be closer to the true value

Question 3

Explain why it is safer for the student to insert the heater into the block before switching on the power supply, and not after

Answer 3

• The heater will heat up very quickly
• So inserting the heater before switching on the power supply could stop the student from burning themselves

Question 4

Describe a method that would allow the student to measure out 300g of the liquid into a flask

Answer 4

• Put the empty flask onto an electronic balance, and set the balance to zero
• Pour the liquid into the flask until the balance displays 300g

Question 5

What could the student change about one piece of apparatus to improve the accuracy of their results?

Answer 5

• Use a digital thermometer instead of an analogue glass thermometer
• This may reduce the random errors that may occur from the student having to determine the temperature from an analogue scale e.g. parallax errors

Question 6

Explain one other way that the student can improve their experiment

Answer 6

• Put a lid on the flask to prevent liquid from evaporating away
• Do several repeats of the experiment and calculate a mean of the results to improve accuracy