Chapter 2 #2

Question 1

Uncertainty of a metre rule vs a micrometer?

Answer 1

Metre rule: 0.5 mm; Micrometer: 0.01 mm.

Question 2

Range and uncertainty of Vernier calipers?

Answer 2

Range ≈ 100 mm; uncertainty 0.1 mm.

Question 3

Formula for micrometer reading?

Answer 3

Reading (mm) = horizontal scale + (vertical scale ÷ 100).

Question 4

How to handle significant figures when squaring a number?

Answer 4

Result keeps same number of significant figures as original.

Question 5

Define Systematic Error (+ examples).

Answer 5

Constant error due to faulty apparatus. Examples: zero error, mis-calibrated scale, slow stopwatch.

Question 6

Define Random Error. How to reduce it?

Answer 6

Error due to scattered readings. Reduced by repeating and averaging.

Question 7

How do Systematic and Random errors affect results?

Answer 7

Systematic reduces accuracy; Random reduces precision.

Question 8

Precision vs Accuracy?

Answer 8

Accuracy: readings peak at true value. Precision: readings tightly grouped.

Question 9

Rule for significant figures when multiplying or dividing?

Answer 9

Use lowest number of significant figures from inputs.

Question 10

Uncertainty when adding quantities?

Answer 10

Add absolute uncertainties.

Question 11

Uncertainty when multiplying quantities?

Answer 11

Add percentage or fractional uncertainties.

Question 12

If x has 5% uncertainty, what is uncertainty of x^3?

Answer 12

15%.

Question 13

Uncertainty of a quantity raised to a power?

Answer 13

Multiply percentage uncertainty by power.

Question 14

Absolute uncertainty always rounded to how many s.f.?

Answer 14

1 significant figure.

Question 15

Rule for decimal places of value and uncertainty?

Answer 15

They must match.

Question 16

CRO: What do Y-gain and Time-base control?

Answer 16

Y-gain: amplitude (voltage). Time-base: time/frequency.

Question 17

How to calculate frequency from a CRO trace?

Answer 17

Period = divisions × time-base; Frequency = 1 ÷ period.

Question 18

If a meter’s scale differs from its range how to find actual reading?

Answer 18

(Reading on scale) / (max scale) = (actual reading) / (max range).