Topic 2.0 Measurement Techniques

Question 1

What are the tools for measuring length?

Answer 1

1. The Metre Rule
2. The Micrometer Screw Gauge
3. The Vernier Caliper

Question 2

What is the uncertainty of a metre rule?

Answer 2

0.5 mm (1 mm since you measure at two points)

Question 3

What are the three possible sources of error in using a metre rule?

Answer 3

1. Zero Error - the end of the rule is worn.
2. Systematic Error - the calibration of the metre rule being incorrect due to the markings.
3. Parallax Rule - the angle at which the rule is viewed.

Question 4

What are the details of the micrometer screw gauge?

Answer 4

Maximum of 50 mm.
Uncertainty of 10 micrometers or less. (0.01 mm)
Each pitch is 0.5 mm.
And the thimble is 100 mm in total.

Question 5

What are the details of the vernier caliper?

Answer 5

Range up to 100 mm.
Can be read to 0.1 mm or 0.05 mm.
Uncertainty is 0.1 mm.

Question 6

Measurement of Pressure Difference in a Manometer?

Answer 6

P = patm + Δhρg

Question 7

Methods of measuring mass?

Answer 7

1. The top-pan balance.

2. The spring balance and the lever balance.

Question 8

Details of the top-pan balance?

Answer 8

1. Ensure that the initial reading is zero.
2. The uncertainty of a particular top-pan will be quoted in the manufacturer’s manual.
3. Percentage uncertainty.

Question 9

Details of the spring and the lever balance.

Answer 9

1. Based on Hooke’s law - the extension of a loaded spring is proportional to the load.
2. Watch out for parallax.
3. Check for zero error.
4. Uncertainty can be obtained from the smallest division on the scale.

Question 10

Details of a c.r.o.?

Answer 10

1. T = Lx
2. frequency = 1/T
   3.

Question 11

Details of measuring temperature?

Answer 11

1. Kelvin to Celsius: θ = T - 273.15°

2.

Question 12

Details of measuring current?

Answer 12

1. Analogue meters & digital.
2. Check for zero error.
3. Check for parallax.
   4.