Practical/Planning

Question 1

What is a safety precaution when using oil/water?

Answer 1

Mop up spillages of oil/water

Question 2

What are 3 safety precautions when using a load?

Answer 2

• Cushion with sand in case load falls
• Keep feet away
• Keep distance from experiment

Question 3

What is a safety precaution when using a ball?

Answer 3

Use a box with cushion to reduce bouncing/rolling

Question 4

What is a safety precuation when using rotating/vibrating parts/pressure chamber?

Answer 4

Use a protective screen

Question 5

What are 2 safety precautions when a hot body is used?

Answer 5

• Wear heat insulating gloves.

* Do not touch hot objects.

Question 6

What are 2 safety precautions when a light source is used?

Answer 6

• Do not look directly at bright light source or wear dark glasses.
• Laser must be pointed away from experimenter.

Question 7

What are 2 safety precautions when a source is used?

Answer 7

• Wear ear defenders

* Switch on sound source for short period of time.

Question 8

What is a safety precaution when high voltage source is used?

Answer 8

Wear rubber gloves

Question 9

What are 2 safety precautions when a normal/low voltage source is used?

Answer 9

• Switch off power supply when not in use to avoid overheating of wire.
• Do not touch coil because it is hot.

Question 10

What are 3 safety precautions when radioactive items are used?

Answer 10

• The source is handled by a tong.
• The source is stored in a lead lined box when not in use.
• Avoid pointing source at people or /do not look directly at source.

Question 11

How to measure time when time <10s and time >10s ?

Answer 11

> 10s:
Detection - Eye
Measuring device - Stopwatch

< 10s:
Detection - Light gates
Measuring device - Electronic timer

Question 12

How to measure length/distance across different ranges?

Answer 12

> 1.0 m:
Measuring tape

Between 0.10 m – 1.0 m:
Metre rule

< 0.10 m:
Vernier callipers/micrometer screw gauge/travelling microscope

Travelling microscope is used when physical contact
with body is not recommended.

Question 13

How to measure volume?

Answer 13

Immerse the body in a beaker of water and measure the volume of water displaced using measuring cylinder.

Question 14

How to measure mass?

Answer 14

Electronic balance

Question 15

How to measure angle?

Answer 15

Protractor or trigonometric methods

Question 16

How to measure instantenous speed of an object?

Answer 16

detect using light gates
indirect measurement
speed v can be calculated using D/t
D = fixed distance between light gates
D kept small to get accurate instantenous speed
t = time taken to travel distance D

Diagram: two light gates connected to a timer.

Question 17

How to measure constant speed of a body? (slow speed)

Answer 17

detection: eye
indirect measurement
speed v can be calculated by D/t
D = fixed distance using ruler
t = time taken to travel D
measured using stop watch

Question 18

How to measure fast speed?

Answer 18

detect using light gates
fire a rifle
same as instanteous speed
speed v =D/t 
D = fixed distance between light gates
t = time taken

Question 19

How to measure speed of water?

Answer 19

Create: tap supplying water to water tank
speed v can be calculated using v = V/A
V = flow rate of water (use flow rate meter)
A = cross sectional area of pipe
Diagram: Tap connected to basin vertically downwards connected to flow ratemeter and then to water out

Question 20

How to measure wind speed?

Answer 20

Create: fan connected to variable power supply or has variable rotating speed
Direct measurement
Measure using wind speed detector

Question 21

How to measure pressure of air/liquid?

Answer 21

Create: Pump connected to chamber
Pressure of air is recorded and measured using pressure gauge.
Diagram: Pump connected to chamber connected to pressure gauge

Question 22

How to measure frequency of oscillating body?

Answer 22

f can be calcuated using f = 1/T
T = period of wave displayed on screen of CRO or time base x no. of division for one complete wave
Diagram: CRO connected to signal generator connected to oscillating body.

Question 23

How to measure force?

Answer 23

Direct measurement using newton meter
Measurement: Using newton meter/spring balance
Diagram: Slotted mass hanging from cable connected to newton meter

Question 24

How to measure angular speed of rotating body?

Answer 24

Connect body to shaft of electric motor
Detection device: Light gates
Angular speed calculated by 2π/T or 2πf
f measured by revolution counter or tachometer

Question 25

How to measure temperature of solid body?

Answer 25

Place object in water bath and use a heating element

Measurement using thermometer

Question 26

How to measure frequency of sound wave?

Answer 26

Detect using microphone connected to CRO
Create a loud speaker placed in front of a pipe
frequency calculated by 1/T
T = time base setting x no. of divisions for 1 complete wave

Question 27

How to measure speed of sound in air

Answer 27

Create long tube fitted with tap & filled with water, tuning fork sounded above the top of the tube.
v = fλ
λ = 2L
L = difference in height of water level for 2 positions where loud sound is heard.

Question 28

How to measure frequency of wire fixed between 2 ends?

Answer 28

Create an oscillator connected to a string secured by pulley and weight
Detect using eye
Measure using CRO
f = 1/T
T = time base setting x no of division for 1 wave on CRO.

Question 29

How to measure frequency of light?

Answer 29

Detect by eye using the microscope
Measuring device: Spectroscope
f calculated by dsinθ = n(c/f)
Diagram: lamp and collimator connected to microscope and diffraction grating at the centre.

Question 30

How to measure wavelength of microwave?

Answer 30

Create a microwave transmitter directed at a metal plate
Wavelength = 2 x L
L = distance moved by receiver for 2 consecutive positions where signal is at maximum.
Diagram: Transmitter connected to power suply directed to metal plate, with receiver connected to CRO in between

Question 31

How to measure magnetic flux density?

Answer 31

Create circular coil connected to a power supply
Detection using hall probe
Measurement: Voltmeter
B = kV, k is a constant that is calculated by putting the hall probe into a known magnetic field.

Question 32

State all additional details that should be considered.

Answer 32

• Mulitple readings of D.V using the same value of I.V to minimise random error
• Take preliminary readings in order to check range of I.V that causes significant change in D.V when readings are varied
• Use spirit level to ensure that items are aligned
• Repeat length measurements for different directions before taking average
• Contrasting colours with background used to ensure that it is easier to observe position
• Reduce external interference due to draughts by switching off fans
• Method to keep C.V constant: same apparatus used to ensure values are constant (same spring for same spring constant)
• Video camera used with playback feature to determine exact moment of motion