Review graphs in Edexcel A-Level Physics through straight-line comparisons, gradient and intercept readings, processed data and logarithmic plots.
A student investigated the behaviour of a thermistor using the circuit shown in the diagram.
She heated the thermistor to 100 °C and measured the potential difference V across it. She decreased the temperature θ and recorded further measurements of V and θ until the temperature reached 10 °C.
The student plotted a graph of her measurements of V and θ.
Estimate the value of V for a temperature of 0 °C.
The student suggested that V is inversely proportional to temperature measured in kelvin.
Determine whether she is correct.
A student investigated the bending of a plastic beam.
The beam, of width w and height h, was supported at either end by two metal rods a distance l apart, as shown.
She applied a force F to the middle of the plastic beam by hanging a mass from it.
The beam bent downwards as shown.
She measured the vertical distance d moved by the middle of the plastic beam and repeated this measurement for increasing values of F.
She recorded her results in a table, as shown.
The “bending modulus” E of the plastic beam can be calculated using the equation
E = l^3F/(4wh^3d)
Show that the gradient of the graph is equal to l^3/(4wh^3E).
A student carried out an experiment to determine the Young modulus of a sample of stainless steel in the form of a wire. The student added weights to the wire and measured the corresponding extensions.
The wire had an unstretched length of 2.6 m . The diameter of the wire was .
The student plotted a graph of weight against extension. The graph showed that the limit of proportionality was not exceeded.
The student's graph is shown below.
Weight / N
Determine the gradient of the graph.
Gradient =