Physical Quantities And Units

Question 1

What is accuracy?

Answer 1

How close a measurement is to its true value

Question 2

What is precision?

Answer 2

A measure of how close a measurement is to its mean value

Question 3

What is a random error?

Answer 3

The unpredictable variation in measurement, usually caused by a force acting out of our control.

Question 4

What is a systematic error?

Answer 4

A consistent shift in readings causing a deviation from the true value, usually caused by uncalibrated equipment.

Question 5

What do all physical quantities consist of? (2 marks)

Answer 5

1. A numerical magnitude
2. A unit

Question 6

What are the SI base quantities and their units? (5 marks)

Answer 6

1. Mass (kg)
2. Length (m)
3. Time (s)
4. Current (A)
5. Temperature (K)

Question 7

What are absolute uncertainties?

Answer 7

The intervals that a value is said to lie within, with a given level of confidence.

Question 8

What is zero errors?

Answer 8

A form of systematic error, caused when a measuring instrument doesn’t read zero at a value of zero - all measurements are offset by a fixed amount.

Question 9

What are the prefixes?

Answer 9

Tera - 10¹²
Giga - 10⁹
Mega - 10⁶
Kilo - 10³
Mili - 10⁻³
Micro - 10⁻⁶
Nano - 10⁻⁹
Pico - 10⁻¹²