WAVE TERMS BUTTONS Click us Clicking on mewillreveal

WAVE TERMS BUTTONS Click us: Clicking on mewillreveal take totoa. SI list ofsome equations, Clicking here allowyou hear information onon the multipliers table. clicking Clicking on Clicking here some information. Clicking here will reveal an answer. Clicking here will move you back a page. Clicking here will bring you back to this page. Clicking here will move you to the next page. me again. Clicking will take you back to the previous page topic. here again stop the sound. return you to will your previous page. TOPICS … describing waves. … transverse and longitudinal waves (3 pages). … the ripple tank. … reflection and refraction (3 pages). … to measure the speed of a water wave (2 pg. ) … practice question. … exam questions 1 and 2.

DESCRIBING WAVES 0. 4 metre Wavelength Length of one wave (metre) Amplitude Crest and Trough Crest is the highest part of a wave= distance speed time = 0. 4 m 2 s = 0. 2 m/s Amplitude The maximum displacement Frequency Speed Trough lowest part of a wave 2 hertz 1 hertz Rest position Frequency Number of waves passing every second (hertz) 0. 5 hertz

TRANSVERSE WAVES Rope oscillations go up and down. The wave carries energy from one place to another. The wave carries energy to the right. In a transverse wave, the particles of the wave move up and down at right angles to the direction of travel of the wave. Water waves and he waves of the electromagnetic spectrum are transverse waves.

LONGITUDINAL WAVES wavelength Y don yn cludo egni i’r dde. In a longitudinal wave the particles move to and fro in the same direction as the direction of travel of the wave. The wavelength of a longitudinal wave is the distance between one compression and the next. Sound waves are longitudinal waves.

WAVE GRAPHS Displacement from rest amplitude distance along the wavelength A graph of the whole wave Displacement from rest amplitude time for one complete oscillation Graph of one particle

THE RIPPLE TANK light source tray of shallow water pattern of waves on a screen plane wavefronts Move the plane wave. The arrow shows the direction of travel of the waves. This is at 90° to the wavefronts. We can’t see this.

REFLECTION Direction of travel of the wave normal lan ew s nt ro ef av angle of incidence reflection r i angle i = angle r barrier Waves reflecting Reflection terms

REFRACTION Wavelength longer DEEPER WATER FASTER speed NO change in frequency Wavelength shorter Wavelength SHALLOW WATER speed DŴR SLOWER B S – LLAI DWFN NO change in frequency Frequency Speed Waves bending Wavelength longer NO change in frequency DEEPER WATER FASTER speed

REFRACTION TERMS normal DEEPER WATER angle of INCIDENCE i When it slows the direction of travel of the wave moves towards the normal. angle of REFRACTION r As it gets faster the direction of travel of the wave moves away from the normal SHALLOWER WATER DEEPER WATER

WATER WAVE SPEED EXPERIMENT 40 cm : CALCULATING SPEED GRAPH stop watch tray Water Depth (cm) Time for wave to travel 3 lengths of the tray. Total distance of 120 cm = 1. 20 m (s) Mean speed (m/s) 1 2 3 Mean time 0. 5 5. 50 5. 39 5. 46 5. 45 0. 22 1. 0 4. 60 3. 75 4. 02 0. 30 1. 5 3. 27 3. 19 3. 60 3. 35 0. 36 2. 0 2. 88 3. 12 3. 19 3. 06 0. 39 2. 5 2. 49 2. 58 2. 61 2. 56 0. 47 3. 0 2. 27 2. 36 2. 45 2. 36 0. 51 speed = distance time = 3 x 0. 40 mean speed = 1. 20 m 5. 45 s = 0. 22 m/s

wave speed m/s SPEED – WATER DEPTH GRAPH EXPERIMENT 0. 6 0. 5 0. 498 0. 4 x 2 0. 3 0. 255 0. 2 x 4 0. 1 0 0 0. 75 cm 1 0. 5 3. 0 cm 1. 5 2 depth of water, cm 2. 5 3 3. 5 Water Depth (cm) Mean speed (m/s) 0. 5 0. 22 1. 0 0. 30 1. 5 0. 36 2. 0 0. 39 2. 5 0. 47 3. 0 0. 51

PRACTICE QUESTION Click on the correct squares only in the grid; amplitude wavelength amplitude wavelength

EXAM QUESTION 1 This is one wave WJEC: Physics 1 June 2016 (Found. ) Q. 4 6 speed = frequency x wavelength = 40 Hz x 120 m = 4800 m/s 8 40 Hz means that 40 waves are passing every second. 4800 speed = distance time = 200 m/s = 150000 m 750 s

EXAM QUESTION 2 WJEC: Physics 1 June 2018 (Found. ) Q. 6 (High. ) Q. 1 In a transverse wave the oscillations are at right angles to the direction of travel of the wave. (ii) Chris suggests that if the depth of water increases four times, the wave speed doubles. Use data from the table opposite to explain whetheror not this statement is true. [2] The statement is true. 3. 13 1. 0 1. 22 x 4 x 2 5. 85 4. 0 A depth of water of 1. 0 m gives a wave speed 6. 26 of 3. 13 m/s. Increasing the depth 4 times to 4 metres doubles the speed to 6. 26 m/s.

EQUATIONS r e igh h er h hig Open the file “Maths for Physics” for more about the use of mathematics in Physics.

SI MULTIPLIERS p - pico k - kilo n - nano M - mega - micro G - giga m - milli T - tera You only see the letter of the prefix on an exam paper, NOT the name. On a Foundation paper only milli, kilo a mega are used.