Practical 8 - Investigation of the variation of resistance with temperature for a metal wire Flashcards
What is the relationship between resistance and temperature?
Resistance increases with temperature for metals in a linear relationship
Draw and label the equipment required for this practical
(See notes)
How do we change the temperature of the water bath for the copper coil?
Heated
What do we do whilst heating the water bath and why?
Stir the water continuously in order to ensure an even temperature throughout the water bath
What are two things we can do to ensure accuracy in this practical?
Stir the water to ensure uniform temperature throughout
Remove the heat before taking a resistance reading
What do we do once each required temperature has been reached?
Remove the heat and record the resistance reading
How can we measure resistance at a temperature of 0 degrees Celsius?
An ice water mixture
Describe the method for this practical
The water bath should be heated and the water stirred continuously in order to ensure an even temperature throughout the water bath
Once the required temperature has been reached, remove the heat and record the resistance reading
Repeat at intervals until the water boils
Repeat during cooling
An ice water mixture can be sped to record the resistance at a temperature of zero degrees Celsius
Plot a graph of resistance (y-axis) against temperature (x-axis) and this should provide a straight line
What goes against the y and x axes on the graph and what should the graph look like?
Y-axis = resistance
X-axis = temperature
Straight line as they have a linear relationship
What would a resistance-temperature graph show if it were to support the suggestion that resistance increases with temperature in a linear relationship?
A straight line with a positive gradient with all data points on or very near the line
How would we get even lower temperature than 0 degrees Celsius in this practical? Why?
Use liquid nitrogen
Is 77 degrees kelvin
How would we get even higher temperatures than 100 degrees Celsius in this practical? Why?
Place the copper coil in oil instead of water - oil boils at very high temperatures
What would be required if we were to alter the experiment to use oil at high temperatures and liquid nitrogen for low temperatures?
A risk assessment
What happens to resistance with an increased temperature and why?
The hotter the wires the higher the random vibrational energy of the ions in it. This causes the electrons to collide with the ions more frequently = increased resistance
What does stirring the water and removing the heat to take a resistance reading ensure?
Accuracy
