Chapter 1 - Physical Quantities & Measurements

Question 1

Prefix and symbol for 1000000000

Answer 1

giga (G)

Question 2

Prefix and symbol for 1000000

Answer 2

mega (M)

Question 3

Prefix and symbol for 1000

Answer 3

kilo (k)

Question 4

Prefix and symbol for 0.1

Answer 4

deci (d)

Question 5

Prefix and symbol for 0.01

Answer 5

centi (c)

Question 6

Prefix and symbol for 0.001

Answer 6

milli (m)

Question 7

Prefix and symbol for 0.000001

Answer 7

micro (µ)

Question 8

Prefix and symbol for 0.000000001

Answer 8

nano (n)

Question 9

What is precision?

Answer 9

reproducibility

Question 10

A measurement is precise if…

Answer 10

it is close to other values obtained by repeating the determination using the same procedure

Question 11

What is accuracy?

Answer 11

correctness

Question 12

A measurement is accurate if…

Answer 12

it is close to the true value.

Question 13

Since the true value of a quantity can never be exactly known, an ________ value is commonly used as the test of ________

Answer 13

accepted

accuracy

Question 14

What is an error?

Answer 14

• anything that causes a measurement to differ from the true value
  or
• the amount by which the measure value differs from the true value

Question 15

A more precise instrument is one that can…

Answer 15

measure smaller intervals

the values given are likely to be closer together, hence it is more precise

Question 16

What is a random error?

Answer 16

An error that occurs inconsistently each time a measurement is repeated

Question 17

Random errors can be caused by…

Answer 17

• the inaccurate reading of the observer from a scale (e.g. parallel error, human judgement error)
• background disturbance (e.g. wind, background noise, vibration in the environment)

Question 18

Random errors cause…

Answer 18

poor precision

Question 19

Random errors can be reduced by…

Answer 19

averaging the results of repeated measurements

Question 20

What is a systematic error?

Answer 20

An error that occurs inconsistently each time a measurement is repeated

Question 21

Systematic errors can be caused by…

Answer 21

• the zero error of the instrument

- the instrument being incorrectly calibrated

Question 22

Systematic errors can be detected by…

Answer 22

comparing with a calibration standard

Question 23

Systematic errors cause…

Answer 23

poor accuracy

Question 24

Systematic errors can be adjusted by…

Answer 24

applying a correction factor

Question 25

Precision indicates…

Answer 25

the size of random errors in a set of measurements

how close the readings are to the average value

Question 26

If an experiment has small random errors, it has ________ precision — the readings are close to the ________ value

Answer 26

high

average

Question 27

Accuracy indicates…

Answer 27

the size of systematic errors in a set of measurements

how close the readings are to the true value

Question 28

If an experiment has small systematic errors, it has ________ accuracy — the readings are close to the ________ value

Answer 28

high

true

Question 29

The number of decimal places is determined by the ________ used

Answer 29

units

Question 30

All non-zero digits are ________

Answer 30

always significant

Question 31

Zeros between two other significant digits are ________

Answer 31

always significant

Question 32

Trailing zeros (on the right) in a number containing a decimal point are ________

Answer 32

significant

Question 33

Leading zeros (on the left) in a number containing a decimal point are ________

Answer 33

not significant

Question 34

The significance of trailing zeros in a number not containing a decimal point can be ________

Answer 34

ambiguous

but in a question, consider 3500 as 4s.f.

Question 35

There should be at least ______ sets of readings for a straight line graph

Answer 35

6

Question 36

There should be at least ______ sets of readings for a curved graph

Answer 36

8

Question 37

Precautions for checking horizontal and vertical alignments [3]

Answer 37

1. Use a spirit level or a plumbline and a set-square to check whether the apparatus or set-up is horizontal or vertical
2. Measure both ends from the top of the bench to judge whether the apparatus or setup is horizontal
3. Make use of the edge of a door, blackboard, or a wall to judge whether the apparatus or set-up is horizontal or vertical

Question 38

Precautions for experiments involving pendulums [3]

Answer 38

1. The angle of oscillation should be not more than 10° so that oscillations are regular
2. Allow the pendulum to swing until the oscillations are steady before taking readings so as to obtain a regular period of oscillation
3. Allow the pendulum bob to swing for a few oscillations to ensure that it is along the vertical plane so as to obtain a regular period of oscillation