Can you draw it?

• 2 people per group– Person A=reporter– Person B=artists

• Reporters, open the black folder and look at the picture . And describe what you see to artists. Artists, draw what reporters are describing.

Rules

• Artists cannot look at the picture in the folder• Reporters cannot comment on artist’s drawing

and artist cannot ask how they are doing.

Start!

What is Wave?

• a wiggle in both space and time • wave extends from one place to another.• source of all waves is something that is

vibrating. Waves are propagations of vibrations throughout space.

Crest

• point on the medium that exhibits the maximum amount of positive or upward displacement from the rest position

Trough

• point on the medium that exhibits the maximum amount of negative or downward displacement from the rest position

Amplitude

• maximum amount of displacement of a particle on the medium from its rest position

• =distance from rest to crest

Wavelength

• distance from any point on a wave to the same point on the next cycle of the wave

• distance from the peak of one wave to the peak on the next wave

• Unit?

Frequency

• how often the particles of the medium vibrate when a wave passes through the medium

• =how many waves per second?

Summary

Speed=wavelength x frequency

Try it on your own!

• What is the v if λ= 8 m and ƒ = 20 Hz?

• What is the λ if v = 50 m/s and ƒ = 25 Hz?

• What is the ƒ if v = 50 m/s and λ= 10 m?

What is Electromagnetic Spectrum?

• Scientists have found that many types of wave can be arranged together like the notes on a piano keyboard, to form a scale

• Sound waves are vibration of air particles• Electromagnetic waves are vibrations of

magnetic and electric fields• Speed of all these waves are 3x10^8

Cont.

• Fill the blanks of the spectrum.• What happens to frequency as wavelength

decreases?• What happens to wavelength as frequency

decreases?• What happens to energy when frequency increases? • http://www.bbc.co.uk/schools/gcsebitesize/

science/21c_pre_2011/radiation/electromagneticradiationact.shtml