Unified Exam paper

Question 1

Define uncertainty

Answer 1

Interval within which the true value can be considered to lie.

Question 2

Define error

Answer 2

The difference between a measurement or results from the true value.

Question 3

How to reduce percentage uncertainty

Answer 3

Make the resolution or the scale divisions smaller.

Make the value larger.

Question 4

Examples of random error

Answer 4

Timing, fluctuations in readings.

Non- uniform diameters

Question 5

Examples of systematic errors

Answer 5

Parallax, zero, energy dissipation or friction.

Question 6

Safety for ionising radiation PAGs

Answer 6

Maximise distance from it, and limit time of usage.

Question 7

Diffraction gratings - how to calculate the largest possible number of orders?

Answer 7

Let theta = 90, so that sin (theta) =1.

Then, solve for x.

Question 8

In your description, state any precautions that you would take to improve the accuracy and
precision of the measurements.

Answer 8

Timing over multiple oscillations, using a fiducial marker, a set square.
Read at eye level to avoid parallax error.
Stir the water. Wait for the temperature to stabilise before taking measurements.
Use large scale increments for precision.
Use an insulated wire.