PHYSICS: WAVE

What is wave?

Waves is the vibration that travels through an object from one place to another or a wave can be described as a disturbance that travels through a medium from one location to another location.

There are 2 types of waves: 

1. Transverse Waves

Transverse waves happen on a rope or on water. Transverse waves are always in a form of a peak and a valley of the wave. The height of the peak and the valley is considered as the amplitude of the wave. A complete wave is always consists of one peak and one valley of the wave. A complete wave is called a wave-length.

An example of transverse waves. There is always a peak and a valley for each complete wave.

2. Longitudinal Waves 

Longitudinal waves are waves that have a compression part and a expansion part, instead of a peak or valley. A complete wave of a longitudinal wave consists of one compression part and one expansion part. The length of a longitudinal wave is equal to the length of a wave that consists of a compression part and a expansion part.

An example of longitudinal waves. You can see a compression and a expansion every wave.

Examples:

1 complete wave = a - b - c - d - e
It consists one peak (a) and one valley (c)

A to B = 1/4
A to C = 1/2
A to D = 3/4

A to E =  1 wave 
A to H =  1 3/4 wave
A to G = 1 1/2 wave 
B to C = 1/4 wave
B to E = 3/4 wave

Exercise On Chapter 18 

1.   Look at the following figure of a pendulum. A motion of 2 Vibrations is shown as the following successive motion .......

   answer:  (B): 2-3-2-1-2-3-2-1












2. Look at the following figure of a pendulum. The part which is considered as the amplitude is . . . .

 answer:  A AND B 

3.    Look at the following figure of a spring. if the spring moves as a-b-c-b-a-b-c-b-a, its motion performs.......

answer: 2 FULL VIBRATION

4.   The number of vibrations performed in every second is ........

                                                   answer: THE FREQUENCY

5.   If a vibration happened in 30 second, the correct statement in the following information is......

                                                      answers: ITS PERIOD IS 1/4 SECOND


6.  A period of a swing is 20 seconds. in every minute, the pendulum will perform......

                                                      answer: 3 SWINGS
              

7.  look at the figure of ruler that is placed on a table. If in 1/4 seconds the ruler moves in the b-c-b-a-b-c-b pattern, period of the vibration made by the ruler is .......


answer:  t/n = (1/4)/(1 1/2)
                  = (1/4)/(3/2)
                  = 1/4 x 2/3
                  = 2/12 = 1/6 seconds





8. If the frequency of a vibration is 340 Hz, the period of such a vibration is........

                                                   answer: (B): 1/340



9.  A pendulum performs swings with a frequency 10 Hz. the number of vibrations that it can make within 5 minutes is.........

                                                     answer:   

                                                             10 Hz => 10 vibrations in one second
                                                             => ? vibrations in 300 seconds (5 min)
                                                              ? = 10 x 300
                                                                 = 3000