Measuring Waves

• Created by: JC:8-9-9
• Created on: 22-12-18 08:53
• Measuring Waves
• Make a phone call -> sound waves converted to electrical waves. Intercontinental phone call, waves carried by electromagnetic waves from ground transmitters to satellites in space & back to ground recievers-> converted back to electrical waves-> sound waves.
• Electronic circuits ensure sound waves similar to original sound waves. Engineers who design and maintain communications - measure diff types of waves at diff stages, so waves not distorted.
• Key Terms
• Displacement
• Of vibrating particle - distance & direction from its equilibrium position
• Amplitude
• Max displacement of vibrating particle. Transverse- height of wave crest / depth of trough from equilibrium position
• Wavelength
• Least distance between 2 adjacent vibrating particles - same displacement & velocity at same time i.e. adjacent crests.
• Cycle
• From max displacement to next max displacement
• Period
• Time for 1 complete wave to pass fixed point
• Frequency
• No. of cycles of vibration of a particle per second/ passing  point per send. Hz
• Period of wave = 1/f
• Wave speed
• Higher frequency of wave, shorter wavelength. i.e. rope(peaks closer together) , ripple-tank(constant f). Frequency higher, waves closer.
• Crests of straight waves travelling at constant speed in ripple tank.- each wave crest is travels distance equal to  wavelength in time taken for 1 cycle.
• Speed of waves c= distance travelled in 1 cycle/ time taken for 1 cycle
• = wavelength/(1/f)=f x wavelength
• Wave speed c=f x wavelength
• Phase Difference
• Between 2 vibrating particles at same frequency is fraction of cycle, 1 cycle- 360 degrees= 2 pi radians.
• Phase Difference in radians= 2 x pi x distance apart on wave / wavelength
• Particles O,P,Q,R,S- spaced ~1/4 of wavelength apart.