RPAs Flashcards
RPA 1: SHC
What is the aim of this investigation?
To determine the specific heat capacity of different materials.
RPA 1: SHC
Describe the 6 steps of this practical.
- Set up your equipment, ensuring to wrap insulation around the base and sides of the block. The heater should fit snugly into one hole in the block.
- If the thermometer has an air gap surrounding it when placed in the second hole, drop water into the hole using a pipette to increase thermal contact.
- If the power of the heater is unknown, switch on the power supply and measure the current and potential. Calculate the power using the equation P = IV.
- Keep the power supply on and start the timer. Measure the temperature of the block every 10 minutes.
- Plot a graph of temperature against work done by the heater. Calculate the gradient of the line.
- Specific heat capacity is the gradient divided by the mass of the block. Since the mass is 1kg, the inverse of the gradient = specific heat capacity of the block.
RPA 1: SHC
Describe the safety precautions needed for this practical.
- Don’t handle the block or heater whilst or after heating.
- Keep the block on a heatproof mat.
- Take care not to spill water near your power supply.
RPA 2: Thermal Insulation
What is the aim of this investigation?
To investigate the effectiveness of different materials as thermal insulators and the factors that affect their insulating properties.
RPA 2: Thermal Insulation
Describe the 6 steps of this practical, testing for both different material types and different thicknesses of insulator.
Method 1 - Testing Different Types of Materials:
1. Set up your equipment, wrapping four of the five beakers with a different insulating material (using the rubber bands to secure the insulation, ensuring as small an air gap between the beaker and insulation as possible).
2. The beaker with no insulation wrapped around it is the control beaker.
3. Cut circles of cardboard (larger than the mouth of the beaker) to form lids for each beaker.
4. Fill each beaker with warm water from the kettle and record the initial temperature of each.
5. Start the stopwatch and measure the temperature of the beakers every 3 minutes.
6. Calculate the change in temperature for each beaker (initial temperature - final temperature).
Method 2 - Testing Different Thicknesses of Insulator:
1. Wrap five beakers in varying thicknesses of one insulating material e.g. wrap each beaker in newspaper using one more sheet per beaker.
2. Fill each beaker with warm water, record the initial temperature and cover each beaker with paper lids.
3. Repeat the experiment as before, measuring the temperature every 3 minutes.
4. Record your results and calculate the change in temperature for each beaker (initial temperature - final temperature).
RPA 2: Thermal Insulation
Describe the safety precautions needed for this practical.
- Don’t handle the beakers whilst or after heating.
- Keep the beakers on a heatproof mat.
- Take care handling glass.
RPA 3: Resistance
What is the aim of this investigation?
To investigate how the resistance of a wire depends on its length and how resistance varies in a series and parallel circuit.
RPA 3: Resistance
Describe the 6 steps of this practical, testing for the resistance of the wire and resistance within a circuit.
Method 1 - The resistance of the wire:
1. Set up a simple circuit, as shown in diagram.
2. Attach a length of wire along a metre ruler using pieces of tape. Attach a crocodile clip to one end (x = 0cm on the ruler).
3. Attach the second crocodile clip at x = 10cm on the ruler and record both the current and voltage through the wire.
4. Repeat by moving the crocodile clip 10cm along the wire and each time recording the current and voltage measured.
5. Calculate the resistance of the wire at each point using the equation V=IR.
6. Plot a graph of the length of the wire (x-axis, units = metres) against the resistance of the wire at that point (y-axis, units = Ω).
Method 2 - Resistance within a Circuit:
1. Construct the circuit shown in diagram 2.
2. Switch on the power supply & close the switch. Record the voltage and current shown.
3. Construct the circuit shown in diagram 3 (rearrange the resistors from series to parallel).
4. Switch on the power supply & close the switch. Record the voltage and ammeter for this circuit arrangement.
5. Calculate the total resistance of each circuit, using the equation V=IR.
RPA 3: Resistance
Describe the safety precautions needed for this practical.
- The uninsulated wire may become hot as
current passes through it. Avoid handling the wire.
RPA 4:
What is the aim of this investigation?
RPA 4:
Describe the 6 steps of this practical.
RPA 4:
Describe the safety precautions needed for this practical.
RPA 5: Density
What is the aim of this investigation?
Determine the densities of regular and irregular solid objects and liquids.
RPA 5: Density
Describe the 5 steps of this practical, for regular and irregular shapes and liquids.
Calculating the Density of Regular Objects:
1. Measure the length, height and width of the object, rounding values to the nearest mm.
2. Calculate the volume by multiplying the length, height and width, giving your value in cm³.
3. Measure the mass of the object, using the mass balance. Remember to reset the balance with nothing on the scales to reduce zero errors.
4. To calculate the density, use the equation d = m/v.
Calculating the Density of Irregular Shaped Objects:
1. Fill the eureka can with room temperature water and align a measuring beaker with the spout.
2. Place the irregular shaped object slowly into the can, ensuring not to drop it from a height or cause it to splash.
3. Collect the displaced water and measure the volume of water displaced.
(The volume of water displaced will equal the volume of the object that caused the displacement.)
4. Measure the mass of the object using a balance.
5. Calculate the density of the irregular object, using the density equation d = m/v.
Calculating the Density of Liquid:
1. Measure the mass of an empty measuring beaker, using a balance.
2. Pour 100cm³ of the liquid into the beaker.
3. Measure the combined mass of the beaker and the liquid.
4. To calculate the liquid’s mass, subtract the mass of the beaker from the mass of the combined beaker and liquid.
5. Calculate the density of the liquid using the density equation.
RPA 5: Density
Describe the safety precautions needed for this practical.
- Take care handling glass equipment.
- Clean any spillages of water.
