Practical Technique

Question 1

What should you do or make sure is correct with digital equipment?

Answer 1

Make sure the equipment is zeroed so the value appearing is correct.

Question 2

Micrometer screw gauge

How to use?

Answer 2

Place item that is to be measured between micrometer and turn the dial at the end to tighten until some resistance is felt and a click is heard.
- Small divisions on inside go up in half mm
- Larger divisions on outside show 0.01mm divisions added on to where it matches up.

Question 3

Linear Vernier Caliper

How to use?

Answer 3

• Each division on the smaller movable piece / scale is 0.05mm
• Each division on the larger fixed piece / scale above is normally in mm
• Where the bottom line’s 0 reading is at, is where you should read from on the top scale and where the bottom line aligns with the top line is where you should read the bottom scale and add them together.

Question 4

Multimeter

Answer 4

• Can measure both Current and Pd.

Question 5

Finding the percentage uncertainty with the line of best fit?

Answer 5

• Draw the line of best fit.
• Calculate the gradient of the line of best fit (m_L ).
• Draw the worst acceptable line of best fit.
• Calculate the gradient of the worst acceptable line of best fit (m_WL).
• Calculate the percentage uncertainty using this formula:
  Difference in gradients / gradient of line of best fit x 100

Question 6

Finding the percentage uncertainty with two worst lines of best fit?

Answer 6

% Uncertainty = m_max - m_min / m_max + m_min x 100

• m_min = gradient of LOBF with smallest acceptable gradient
• m_max = gradient of LOBF with biggest acceptable gradient

Question 7

‘Show that’ Questions

what do you need to keep in mind?

Answer 7

The solution to these questions often requires you to make a calculation or read data from a graph. However, be careful when you do this as you must quote the answer to at least one more significant figure than the number of significant figures quoted in the question.