Unit 5 - 2024

Question 1

Explain, in terms of energy, the shape of a hysteresis graph

Answer 1

The work done on the rubber in stretching is the area under the loading curve.
The work done by the rubber in contracting is the area under the unloading curve.
The mechanical energy lost to internal energy of rubber and to the environment is the area between the two curves

Question 2

Name the 5 regions of a stress-strain graph

Answer 2

limit of proportionality
elastic limit
yield point
ultimate tensile strength
breaking point

Question 3

How do you find the Young’s Modulus of a material from a stress strain graph (2 ways)

Answer 3

gradient of tangent at origin
value of stress/strain at a particular point on the graph

Question 4

Explain the method for how you would determine the Young’s Modulus of the material of a metal wire

Answer 4

Clamp a wire at one end of the table, and stretch it to the other end where it hangs over the edge of the table with weights attached. Add a paper rider to the wire, so the extension can be measured.
Measure diameter using micrometer
Measure original length and add a series of masses. Measure the extension. Take readings when unloading the masses. Plot Tension against extension.

Question 5

Explain the method for investigating the force-extension relationship for rubber

Answer 5

Load and Unload a rubber band, measuring extension from original length.

Question 6

Explain the relationship between resistance and temperature (2 points)

Answer 6

Electrons have a greater velocity at greater temperatures, so they collide more frequently with each other. This reduces the drift velocity, so current decreases (I=nAve), and resistance increases (V=IR).

Resistivity compared to initial resistivity plotted against temperature is straight line, suggesting resistivity of a metal increases with temperature.

Question 7

Explain how you would investigate the IV characteristic of a filament lamp

Answer 7

Using a variable power supply, change the voltage and take readings of current and voltage at each step

Question 8

Explain how you would determine the resistivity of a metal

Answer 8

Use crocodile clips to attach to the wire at different lengths. Take readings of current and voltage at each length. Measure the diameter of the wire using a micrometer.

Question 9

Explain how you could investigate the variation of resistance with temperature

Answer 9

Put a waterproof coil of wire in water in a beaker and heat it. Measure the temperature with a thermometer and plot resistance against temperature.

Question 10

Explain Youngs Double Slit Experiment

Answer 10

Microscope slide prepared using graphite and a scriber. Light shone into the slits and onto the screen. Distance is measured from the slits to the screen. Distance between slits, a, is measured. Fringe separating is measured using a ruler

Question 11

What do each of the terms in lambda = aY/D stand for

Answer 11

lambda = wavelength
a= distance between slits
y= fringe separation
D= distance from slits to screen

Question 12

Explain determination of wavelength using diffraction grating experiment

Answer 12

laser onto diffraction grating. Distance between diffraction grating and screen is measured. Use nlamba=dsintheta.

Question 13

How would you determine the speed of sound using stationary waves

Answer 13

Place a tube of air into a column of water and use a tuning fork above the tube. Adjust the length until the loudest sound is heard. The distance between the node and the antinode is lambda/4.