4 Waves G482 Electricity, Waves & Photons 4 Waves G482 Electricity, Waves & Photons Wave Motion Wave Motion Mr Powell 2012 Index EM Waves EM Waves Interference Interference Stationary Waves Stationary Waves

Mr Powell 2012 Index Practical Skills are assessed using OCR set tasks. The practical work suggested below may be carried out as part of skill development. Centres are not required to carry out all of these experiments.  Students should gain a qualitative understanding of superposition effects together with confidence in handling experimental data.  Students should be able to discuss superposition effects and perform experiments leading to measurements of wavelength and wave velocity.  Study hearing superposition using a signal generator and two loudspeakers.  Demonstrate stationary waves using a slinky spring, tubes and microwaves.  Determine the speed of sound in air by formation of stationary waves in a resonance tube.

Mr Powell 2012 Index Stationary Waves 2 - Microwaves Assessable learning outcomes.... (d) describe experiments to demonstrate stationary waves using microwaves (p160) Assessable learning outcomes.... (d) describe experiments to demonstrate stationary waves using microwaves (p160)

Mr Powell 2012 Index True or False... 1.Travels at the speed of light or 3 x 10 8 (ms –1 in vacuum 2.Travel in vacuum 3.Transverse (wave) / can be polarised 4.Consists of oscillating electric and magnetic fields 5.Can be reflected / refracted / diffracted / shows interference (Behave as) photon(s) 6.Warms food Which is these properties do Microwaves have; some, any or all?

Mr Powell 2012 Index Microwaves can make standing waves In a microwave oven, the microwaves reflect from the walls and form a standing wave pattern in the oven. At the nodes, the food does not get cooked. This is why microwave ovens have a turntable, or have a 'stirrer' to break up the standing wave pattern. You will need 1.microwave transmitter 2.slotted base 3.metal reflector (about 0.3 m square) 4.audio amplifier 5.loudspeaker 6.digital multimeter used as a microammeter 7.diode probe 8.metre rule 9.4 mm leads (d) describe experiments to demonstrate stationary waves using microwaves, stretched strings and air columns; (p160)

Mr Powell 2012 Index (d) describe experiments to demonstrate stationary waves using microwaves, stretched strings and air columns; (p160) You can use an audio amplifier to detect changes in the signal at the diode probe, but you will find that the microammeter allows you to observe changes in the strength of the signal more precisely. You will find that microwaves will reflect off many other surfaces than the metal reflector – including yourself! 1.Place the reflector about 1.5 m from the transmitter. 2.Place the diode probe between the transmitter and the reflector. 3.Slowly move the probe along the line between transmitter and reflector. 4.Note what happens to the strength of the received signal as the probe moves towards the transmitter. 5.Measure the average distance between pairs of minima (two 'lows' of radiation or nodes). 6.Use this to find the wavelength of the radiation. You should have seen that 1.Microwaves can set up stationary wave patterns. 2.The distance between two adjacent nodes is about 15 mm. 3.The wavelength of the radiation is about 30 mm.

Mr Powell 2012 Index Results (28mm wave) – 10.5 GHz

Mr Powell 2012 Index Revision/ Extension… Visit the sites show below and then write a paragraph and numerical example for each. Inverse square law calculation: Geological example of sound reflection: Pitch: Loudness of wave: String properties: Wave properties and more :

Mr Powell 2012 Index Connection Connect your learning to the content of the lesson Share the process by which the learning will actually take place Explore the outcomes of the learning, emphasising why this will be beneficial for the learner Connection Connect your learning to the content of the lesson Share the process by which the learning will actually take place Explore the outcomes of the learning, emphasising why this will be beneficial for the learner Demonstration Use formative feedback – Assessment for Learning Vary the groupings within the classroom for the purpose of learning – individual; pair; group/team; friendship; teacher selected; single sex; mixed sex Offer different ways for the students to demonstrate their understanding Allow the students to “show off” their learning Demonstration Use formative feedback – Assessment for Learning Vary the groupings within the classroom for the purpose of learning – individual; pair; group/team; friendship; teacher selected; single sex; mixed sex Offer different ways for the students to demonstrate their understanding Allow the students to “show off” their learning Activation Construct problem-solving challenges for the students Use a multi-sensory approach – VAK Promote a language of learning to enable the students to talk about their progress or obstacles to it Learning as an active process, so the students aren’t passive receptors Activation Construct problem-solving challenges for the students Use a multi-sensory approach – VAK Promote a language of learning to enable the students to talk about their progress or obstacles to it Learning as an active process, so the students aren’t passive receptors Consolidation Structure active reflection on the lesson content and the process of learning Seek transfer between “subjects” Review the learning from this lesson and preview the learning for the next Promote ways in which the students will remember A “news broadcast” approach to learning Consolidation Structure active reflection on the lesson content and the process of learning Seek transfer between “subjects” Review the learning from this lesson and preview the learning for the next Promote ways in which the students will remember A “news broadcast” approach to learning

Mr Powell 2012 Index

Mr Powell 2012 Index

Mr Powell 2012 Index In a stationary wave all the particles in a between a node are acting in phase.. i.e. they travel up at the same time. In a progressive wave each part of the wave is out of phase as you move along the wave through 360  ……. Q3

Mr Powell 2012 Index