OCR Purposeful Practicals
Density of Regular and Irregular Objects
To calculate the density you need to measure the mass and volume. A regular solid, irregular solid and a liquid are used in this video to illustrate three methods of calculating the density.
Density of Regular and Irregular Objects - RESULTS
This is the data that was recorded and how it is used to calculate the density. Take care with your use of standard form and how you convert from millilitres to cubic metres.
Force and Extension for a Spring
By applying small masses to a standard spring we apply a force that causes an extension. This data can be plotted to investigate the relationship between these two quantities.
Caution: Wear safety goggles in case the spring flicks into your eye.
Force and Extension for a Spring - RESULTS
These results can be used to demonstrate Hooke's Law and can also be used to determine the spring constant for the spring.
Speed of Waves in a Solid
In this experiment a wave is sent through a solid, I used elastic although string is also often used in schools. By adjusting the frequency a standing wave is formed from which the wavelength can be measured.
Reflection of Light (including RESULTS)
Light from a ray box is reflected from a plane mirror and the angle of incidence and reflection is measured - including an example from a different surface.
Refraction of Light
As the light enters the glass block it slows down and changes direction. We can measure the angle of refraction to investigate the relationship between 'i' and 'r'.
Refraction of Light - RESULTS
In this video the relationship between the angle of incidence and angle of refraction is explored.
Investigating acceleration by varying force (constant mass)
In this experiment the force that is applied to the trolley is changed - but the total mass remains constant. The acceleration can then be measured.
Caution: Take care when the weights are falling onto the floor.
Investigating acceleration by varying force (constant mass) - RESULTS
These are the results displayed on graph with the force on the x-axis and the acceleration on the y-axis
Investigating acceleration by varying mass (constant force)
This experiment is different to the first one. Now the force remains constant but the total mass is increased by adding 100g masses.
Caution: Take care when the weights are falling onto the floor.
Investigating acceleration by varying mass (constant force) - RESULTS
To really investigate the relationship between mass and acceleration a graph is plotted with 1/m against acceleration. I also explain how this leads onto Newton's Second Law.
Waves on a Ripple Tank (measuring Frequency and Wavelength) and RESULTS
The speed of water waves on a ripple tank can be calculated by measuring the frequency (using slow motion footage) and the wavelength (from a photograph).
Specific Heat Capacity of Solids
This video shows a standard school experiment where the specific heat capacity of a 1kg block of aluminium is heated with an electric immersion heater. It is left for ten minutes so you can take results of the temperature during this time.
Specific Heat Capacity of Solids - RESULTS
This is quite an involved analysis - with the gradient of the graph used to find the specific heat capacity of aluminium. In this video I explain how I did this and why my experimental value may be slightly too high.
Characteristics of a Resistor
A resistor is connected into a circuit where an ammeter is used to measure the current through it and a voltmeter is used to measure the potential difference across it. In this experiment a variable power supply is used change these values before an IV graph is plotted.
Characteristics of a Resistor - RESULTS
These are the results from the previous practical - the shape of the IV graph allows you to identify the component.
Characteristics of a Lamp
This experiment uses a similar set-up to the previous experiment with a resistor - but we now investigate the characteristics of a filament lamp bulb.
Caution: The bulb may become hot!
Characteristics of a Lamp - RESULTS
The shape of this graph shows that its resistance is not constant - it increases with current.
Characteristics of a Diode
It is important to remember that we only connect the voltmeter across the diode in the circuit. The other resistor is just there to stop the circuit overheating.
Caution: Only keep the circuit switched on for a short time when a high current is measured!
Characteristics of a Diode - RESULTS
For these results I made sure that I used a suitable scale for the potential difference when I plotted this on the graph.
Resistors in Series and Parallel
This experiment looks at the total resistance when two resistors are combined in both series and parallel combinations.
Resistors in Series and Parallel - RESULTS
These are my results and how I calculated the resistance of each resistor combination.