# Unit Planner: Oscillations and waves

Unit 8: Oscillations and waves

Start date:

**Diploma assessment**

*When will the content be assessed?*

*Paper 1 xPaper 2 xPaper 3 xInvestigation x*

**Text book reference**

Hamper Chapter 5

#### Inquiry: Establishing the purpose of the unit

**Transfer Goals***List here one to three big, overarching, long-term goals for this unit. Transfer goals are the major goals that ask students to “transfer”, or apply, their knowledge, skills, and concepts at the end of the unit under new/different circumstances, and on their own without scaffolding from the teacher. *

- The sinusoidal nature of oscillations
- All waves reflect, refract, diffract and interfere
- All waves have the same mathematical model

**Content***List here the key content that students will know by the end of the unit *

- Describe the motion of a simple pendulum and mass on a spring
- Graphs of motion for SHM
- Define frequency, amplitude and time period
- Define SHM
- Describe and graph energy changes in SHM
- Describe phase difference
- Define frequency, amplitude , wavelength and wave velocity
- Describe reflection, refraction, diffraction, polarisation and interference
- Differentiate between longitudinal and transverse waves
- Represent waves graphically
- Identify the difference between standing and progressive waves
- pitch and loudness of sound
- The EM spectrum
- TIR
- Optical fibres
- Young's slits
- Malus' law

**Skills***List here the key skills that students will develop by the end of the unit. *

- Methods of timing
- Fitting sin curves in LoggerPro
- Video analysis
- modeling with GeoGebra
- Using Algodoo to model light
- Sketching graphs to represent waves

**Concepts***List here the key concepts that students will understand by the end of the unit*

- Circular motion can be used to model SHM
- SHM is a consequence of the force being proportional and opposite to displacement
- If graph of s vs t is a sin curve then v vst t is cos and a vs t -sin
- Phase
- A wave is a series of out of phase oscillations
- understanding what A,B and C stand for in y = A sin(Bx +C)
- Explain reflection, refraction, diffraction, polarisation and interference
- Explain the formation of standing waves
- Use Huygen's construction to explain wave phenomena
- Sound is a pressure wave
- The role of interference and diffraction in Young's slits
- Phase change on reflection
- Change of polarisation plane on passing through a polariser
- Conditions for a standing wave in a string and pipes
- Relationship between path and phase difference

**Applications***Examples of real world practical applications of knowledge. *

- Sound insulation
- Noise cancelling headphones
- Surfing

#### Action: teaching and learning through Inquiry

**Approaches to teaching***Tick boxes to indicate pedagogical approaches used. *

*Lecture*

Simulation x

Small group work (pairs) x

Hands on practical x

Video x

Simulation x

Small group work (pairs) x

Hands on practical x

Video x

*Student centred inquiry x*

**TOK***Examples of how TOK can be introduced in this unit *

**Patterns in nature; many unrelated examples have the same equation.**- Here, as usual, we start by looking at an example of motion, the simple pendulum, then simplify it (small angles) so that we can make a mathematical model for its motion.
**Up to this point in the course everything has been described in terms of particles but water waves do not fit into the same model hence the need to introduce a new model; the wave.****Water waves have certain properties, anything else that has the same properties is also called a wave**e.g. light, sound etc. but if we could see light waves (haha light is the only thing we can see) would it be a wave like a water wave?- The word wave was probably first used for water waves but is now used for many other physical phenomena.
- When doing the Waves in a bucket experiment students often think that the wave speed depends on how hard they push the bucket. This is because it feels that way, however the equation for the wave tells us something else.
- Simulations on SMARTboards have made wave motion much easier to visualise. What is the role of visualisation in the acquisition of knowledge?
- Why is the musical scale made up of such strange frequencies, wouldn't it be easier if it were decimalised?
- Is it important for musicians to understand about standing waves?
- If a musician understands the physics of the instrument does it make them a better musician or does it spoil the experience?
- Perception and measurement. Pitch and Loudness are perceived but frequency and intensity are measured.
- The difference between perception and measured quantity. Colour is perceived wavelength is measured. Loudness perceived, intensity measured.
- Just because rotating bits of plastic causes light intensity to vary does this mean light is being polarised.

**NOS***Examples of how NOS can be introduced in this unit. *

After observing the regular motion of a pendulum, we can apply Newton's laws of motion the the bob and derive an equation for its motion that can be tested by experiment

A pendulum is not the same as a mass on a spring but the have common equations defining their motion.

If you do the video analysis demonstration then might be worth highlighting the way we fit the sine curve to the points. How do we know it's a sine function? Do we just try fitting a sine curve because it looks like one? What do the different coefficients represent?

The equations developed to model mechanical waves such as the waves in a string can be used to model other, not directly observable waves, such as light and sound.

The repeating theme of using graphs to represent physical phenomena

**Snell's law comes from experiment but also gives the shortest route from A-B as predicted by the theory of relativity. You can show this by**considering the quickest path that a camel should take when walking across the line between an area of baked earth and sand.**This is an example of how different models are consistent.**- Huygens' construction is a way of finding the new wavefront position by considering wavelets travelling forwards only with no explanation as to why the wave doesn't propagate backwards as well.
- Could look at the different ways of measuring the speed of sound. If you have stereo microphones you could measure the time delay with audacity. Advances in technology lead to improved measurement.
- The explanation of polarised light is an example of how a mechanical model that we can see (waves in strings) can be used to model something that we can't see (the wave motion of light).

**Assessments***Tests, exams and marked labs*

MC Quizzes

**worksheets and exercises**

**Resources***Video clips, simulations demonstrations etc*.

#### Reflections

**What went well***List the portions of the unit (content, assessment, planning) that were successful *

**What didn’t work well***List the portions of the unit (content, assessment, planning) that were not as successful as hoped *

**Notes/changes/suggestions:***List any notes, suggestions, or considerations for the future teaching of this unit*.