Attendens

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Wave BEHAVIOR. Section3:. WAVE BEHAVIOU.

starter. Wave behavior • Waves act in many different ways (ex. sound waves and light waves), and may produce a: — Refection Rcfrö<töon Interference.

Section3: wave behavior. Essential questions How are wave reflected and refracted at boundaries between medium? How does the principle of superposition apply to the phenomenon of interference?.

Recall. Incident Reflected Absorbed Transmitted.

Waves at boundaries. Wave at a Boundary Mncident Vreflected Vtransmitted Figure 13 When the wave pulse meets the boundary between the two springs, a transmitted wave pulse and a reflected wave form. Compare the energy of the incident wave to the energy of the reflected wave..

The Video Show.

Rigid boundaries. Vincident Vreflected. Rigid boundaries When a wave pulse hits a rigid boundary, the energy is reflected back, as shown in Figure 14. The wall is the boundary of a new medium through which the wave attempts to pass. Instead of pass- ing through, the pulse is reflected from the wall with almost exactly the same amplitude as the pulse of the incident wave. Thus, almost all the wave's energy is reflected back. Very little energy is transmitted into the wall. Also note that the pulse is inverted..

VVaves at boundaries Incident xuave — initial vvave that strikes a boundary. Reflected vvave — returning vvave after the collision Of the incident vvave vvith a bou nda ry. B e fore reflection After reflection B e fore reflection (b) After reflection Fixed bound a condition condition.

Interference of waves. Graphical user interface, diagram Description automatically generated.

Principle of Superposition When two waves exist in the same place in the medium at the same time the displacement of the medium is equal to sum of the two individual wave displacements crest + crest a trough • trough crest trough a resunant amplitude 2a c ive resultant amplitude constructive resultant amplitude = O destructive.

Wave Interference - the result of the superposition of two or more waves Destructive - when two waves with opposite amplitudes meet, If these are equal amplitudes then the point that they meet (node) does not move Constructive - when two waves with amplitudes in the same direction meet, Produces an a point where the largest amount of displacement occurs (antinode), When two equal pulses meet, there is a point, called the node (N), where the medium remains undisturbed (a). Constructive interference results in maximum interference at the antinode (A) (b). If the opposite pulses have unequal amplitudes, cancellation is incomplete (c)..

1- Constructive interference. Text Description automatically generated.

2- Destructive interference. Graphical user interface Description automatically generated.

Destructive Interference Constructive Interference Different Amplitudes.

Standing wave. o, o, 2 Figure 17 Interference produces standing waves only at certain frequencies. Predict the wavelength if the frequency is four times the lowest frequency..

Evaluation question. Predict the wavelength if the frequency is fourth times the lowest frequency.

Waves in two dimensions 1-picturing wave in two dimensions.

2-Creating two-dimensional waves. 3- reflection in two-dimensional waves.

4- refraction in wave in two dimensions. Shallower water, lower speed, shorter wavelength Deeper water, greater speed, longer wavelength Refraction.

Evaluation question. READING CHECK Predict the factor by which the wavelength changes if the speed of the refracted wave is half that of the incident wave..

Solve the question page 108.

76. Sketch the result for each of the three cases shown in Figure 24, when the centers of the two approaching wave pulses lie on the dashed line so that the pulses exactly overlap. Figure 24.

55. Suppose you send a pulse along a rope. How does the position of a point on the rope before the pulse arrives compare to the point's position after the pulse has passed?.

45. Car Shocks Each of the coil springs of a car has a spring constant of 25,000 N / rn- Hovv is each spring cornpressed if ic supports one-fourth of the car's 12,000 N vveight?.

Suppose you produce a transverse vvave by shaking 58. one end of a spring fron• side to side. I--lovv does the frequency of your hand connpare vvith the frequency of the vvave?.

63. The wavelength of water waves in a shallow dish is 6.0 cm. The water moves up and down at a rate of 4.8 oscillations/s. a. VVhat is the speed of the waves? b. What is the period of the waves?.