Waves

Rowena D. Olicia

CTP-LEAPPhilippines

4th Year

TARGETS

At the end of the lesson, 75% of the students should be able to:

Define waves. Identify the characteristics of wave. Solve problems on waves.

WAVES

are disturbances that propagate through space

are also called energy carriers transfer energy from one point to another

do not carry the particle of matter only cause particle of matter to vibrate / move back and forth

Parts of Waves

Wavelength Amplitude A

distance

time

wave crest

wave trough

wavelength

amplitude

Examples of Waves

Water surface waves Sound Electromagnetic Waves (EM Waves)

- radio/TV waves, microwave, infrared, visible light, ultraviolet, X-rays, gamma

Seismic waves

Wave Characteristics

Characteristics of Waves

Frequency f (inverse of period T) number of cycles per second (Hertz)

f = c / T = 1 / f

T

Wavelength (λ) distance between successive

identical parts of a wave distance the wave has traveled in

one complete cycle

EM Spectrum

www.andor.com/

Amplitude

Maximum displacement from the equilibrium (midpoint) position

Measure of how much energy the wave has

Frequency (f)

number of waves that pass a given point per unit of timeUnit: hertz (Hz)

Period (T)

time for a wave to complete a cycle reciprocal of frequencyT= 1/f

Wave Speed (v)speed with which waves pass a

particular pointWave speed = wavelength / period v = λ / T or v = λf

Sample Problems

1) A vibration of frequency 5Hz sends a wave of 0.8m down a rope. What is the speed of the wave?

2) A wave of wavelength 1.5m travels down a rope at a speed of 6m/s. What is the frequency of the wave?

Solutions

1) Given:frequency (f) = 5Hzwavelength (λ) =0.8mspeed (v) =?

Formula:V =f x V = 5 Hz x 0.8m

V = 4.0 m/s

2) Given:

velocity (v) = 6m/swavelength(λ)= 1.5mfrequency (f) = ?

Formula: f= v/ f= 6m/s

1.5m f= 4Hz

SUMMARY

I. Waves disturbances in space/matter energy carriers

II. Kinds Mechanical Waves (need a medium)

a. longitudinal (propagation parallel to motion)

ex. soundb. transverse (propagation perpendicular to motion)

ex. String wave EM Waves (do not need a medium)

ex. Radio/TV waves, microwave, visible light, UV, X-rays

SUMMARY

III. Wave Characteristics Wavelength (crest-crest; trough-

trough) Frequency (no. of waves per second) Amplitude (maximum displacement)

Period (time to complete one cycle) Wave speed(wavelength over period)

wavecrossword.jcw

REFERENCES

http://hyperphysics.phy-astr.gsu.edu/hbase/sound/tralon.html

sol.sci.uop.edu/.../chapter10/refraction.jpg

www.gcsescience.com/Transverse-Wave.gif

http://dev.physicslab.org/

http://www.physicsclassroom.com/Class/waves/U10L3c.html

www.fen.upc.edu/