RPs Flashcards
Specific Heat Capacity required practical:
Aim of the experiment
To measure the specific heat capacity of a sample of material.
Method
Place the immersion heater into the central hole at the top of the block.
Place the thermometer into the smaller hole and put a couple of drops of oil into the hole to make sure the thermometer is surrounded by hot material.
Fully insulate the block by wrapping it loosely with cotton wool.
Record the temperature of the block.
Connect the heater to the power supply and turn it off after ten minutes.
After ten minutes the temperature will still rise even though the heater has been turned off and then it will begin to cool. Record the highest temperature that it reaches and calculate the temperature rise during the experiment.
Safety:Do not touch when switched on. Position away from the edge of the desk. Allow time to cool before packing away equipment. Run any burn under cold running water for at least 10 minutes.
Independent: Time (s)
Dependent: Temperature (°C)
Control: Volume of water, starting temperature, material thickness.
Aim of the experiment:
To compare the effectiveness of different materials as thermal insulators.
Method
Place a small beaker into a larger beaker.
Fill the small beaker with hot water from a kettle.
Put a piece of cardboard over the beakers as a lid. The lid should have a hole suitable for a thermometer.
Place a thermometer into the smaller beaker through the hole.
Record the temperature of the water in the small beaker and start the stopwatch.
Record the temperature of the water every 2 minutes for 20 minutes.
Repeat steps 1-6, each time packing the space between the large beaker and small beaker with the chosen insulating material.
Plot a graph of temperature (y-axis) against time (x-axis).
Safety:Do not overfill the kettle. Place the small beaker inside the large beaker before gently pouring the water.
Independent:Layers of insulation
Dependent: Temperature change.
Control: Heater power, block material. volume of water
Investigating Resistance
Aim of the experiment
To investigate how changing the length of the wire affects its resistance.
Method
Connect the circuit as shown in the diagram above.
Connect the crocodile clips to the resistance wire, 100 centimetres (cm) apart.
Record the reading on the ammeter and on the voltmeter.
Move one of the crocodile clips closer until they are 90 cm apart.
Record the new readings on the ammeter and the voltmeter.
Repeat the previous steps reducing the length of the wire by 10 cm each time down to a minimum length of 10 cm.
Use the results to calculate the resistance of each length of wire by using R = V/I, where R is resistance, V is voltage and I is current.
Plot a graph of resistance against length for the resistance wire.
Safety: Do not touch the resistance wire whilst the circuit is connected. Allow the wire time to cool. Switch off power occasionally.
Independent: Wire length.
Dependent: Resistance.
Control: Power supply voltage, wire temperature.
Investigating I-V Characteristics
Aim of the experiment
To compare the total resistance in
series and parallel arrangements.
1) Set up a circuit with a voltage supply, ammeter, fixed and variable resistor
2) Vary the voltage across the component by changing the resistance of the variable resistor,
using a wide range of voltages, bet ween 8-10 readings
3) For each voltage, record the value of the current from the ammeter 3 times and calculate
the average current
4) Increase the voltage further in steps of 0.5V, repeating steps 2 and 3
5) Reverse the the terminals of the power supply and take
readings for the negative voltage/current
6) Replace the fixed resistor with the filament lamp, then
the diode, repeating the experiment for each
Safety: Make sure to switch off the circuit in
bet ween readings to prevent heating of the
component and wires
Independent: resistor type
Dependent graph
Control: same circuit
Density of Irregular Objects
Method:
Fill a eureka can, place a measuring cylinder under its spout.
Submerge the object, collect displaced water, and record volume.
Measure the object’s mass using a balance.
Calculate density:
density=mass/volume
Investigating Hooke’s Law
Aim of the experiment
To investigate the relationship between force and extension for a spring.
Method:
Secure a clamp stand to the bench using a G-clamp or a large mass on the base.
Use bosses to attach two clamps to the clamp stand.
Attach the spring to the top clamp, and a ruler to the bottom clamp.
Adjust the ruler so that it is vertical, and with its zero level with the top of the spring.
Measure and record the unloaded length of the spring.
Hang a 100 g slotted mass carrier - weight 0.98 newtons (N) - from the spring. Measure and record the new length of the spring.
Add a 100 g slotted mass to the carrier. Measure and record the new length of the spring.
Repeat step 7 until you have added a total of 1,000 g.
Safety:Careful handling heavy weights to not drop on your feet
Independent: Force (N).
Dependent: Extension (m).
Investigating the effect of varying mass and force on acceleration of an object.
Aim:Investigate Newton’s second Law
Method:
The trolley is connected to the masses by a string through a pulley. The weight of these masses will be the force used in the calculations.
Mark a starting point on the surface that you’re doing the experiment. The trolley must start at this point every time. Hold the trolley stationary at the start line, making sure that the string is not loose.
Release the trolley. Record the acceleration of the trolley that the light gate measures.
Repeat this at least two more times with the same masses, and calculate an average acceleration. This will be the average acceleration of the whole system.
Use same the experimental method, but each time add more mass to the trolley (not on the mass hook), and record the average acceleration.
The force is kept constant, because the force is the weight of the masses on the hook.
So as more masses are added to the trolley, the acceleration should decrease
To investigate varying force:
Use same the experimental method, however start with all masses on the trolley.
Then take a mass off the trolley, add it to the hook, and record the acceleration each time. This way, the mass of the whole system is not changing (because the mass is just being transferred from one place in the system to another).
The acceleration should increase as the force increases
Independent variable: Mass of weights on trolley, and on hook
Dependent variable: Acceleration
Control:Pulley, Same starting point
Waves Required Practical:
Aim:Investigate waves with a ripple tank for water waves, stretched string for waves in a solid and a signal generator and loudspeaker for sound waves
Method:
For water waves:
Set up the ripple tank as shown in the diagram with about 5 cm depth of water.
Adjust the height of the wooden rod so that it just touches the surface of the water.
Switch on the lamp and motor and adjust until low frequency waves can be clearly observed.
Measure the length of a number of waves then divide by the number of waves to record wavelength. It may be more practical to take a photograph of the card with the ruler and take measurements from the still picture.
Count the number of waves passing a point in ten seconds then divide by ten to record frequency.
Calculate the speed of the waves using: wave speed = frequency × wavelength.
For sound waves:
Attach a string or cord to a vibration generator and use a 200 gram (g) hanging mass and pulley to pull the string taut as shown in the diagram. Place a wooden bridge under the string near the pulley.
Switch on the vibration generator and adjust the wooden bridge until stationary waves can be clearly observed.
Measure the length of as many half wavelengths (loops) as possible, divide by the number of half wavelengths (loops). This is half the wavelength, doubling this gives the wavelength.
The frequency is the frequency of the power supply.
Calculate the speed of the waves using: wave speed = frequency × wavelength.
Reflection/Refraction
Aim of the experiment
To investigate the reflection of light by different types of surface, and the refraction of light by different substances.
Method
Set up a ray box, slit and lens so that a narrow ray of light is produced.
Place a 30 centimetre (cm) ruler near the middle of a piece of plain paper. Draw a straight line parallel to its longer sides. Use a protractor to draw a second line at right angles to this line. Label this line with an ‘N’ for ‘normal’.
Place the longest side of a rectangular
glass block against the first line. With the normal near the middle of the block, carefully draw around the block without moving it.
Use the ray box to shine a ray of light at the point where the normal meets the block. This is the incident ray.
The angle between the normal and the incident ray is called the angle of incidence.
Move the ray box or paper to change the angle of incidence. The aim is to see a clear ray reflected from the surface of the block and another clear ray leaving the opposite face of the block.
Using a pencil on the paper, mark the path of:
the incident ray with a cross
the reflected ray with a cross
the ray that leaves the block with two crosses - one near the block and the other further away
Remove the block. Join the crosses to show the paths of the light rays.
Replace the block within its outline and repeat the above process for a ray striking the
block at a different angle
Independent variable: angle of incidence
Dependent variable: angle of reflection
Infrared Radiation Required Practical:
Aim of the experiment
To investigate how the amount of infrared radiation absorbed or radiated by a surface depends on the nature of that surface.
Method
Place a Leslie cube on a heat-resistant mat. Fill it, almost to the top, with boiling water and replace the lid.
Leave for one minute. This is to enable the surfaces to heat up to the temperature of the water.
Use the infrared detector to measure the intensity of infrared radiation emitted from each surface, or the temperature of the surface. Make sure that the detector is the same distance from each surface for each reading.
