science 7

1. Wave
Waves are disturbances in a medium that generates a series of
pulse traveling at a regular interval carrying energy through
matter or space.

2. Classification:
Pulse Wave – A wave that is consist
of a single traveling pulse.
Periodic Wave – A wave consists of a
series of pulse

3. Medium – The matter through which a wave travels.

4. TYPES OF WAVES
1.Mechanical Waves – A wave that require a medium.
2. Electromagnetic Waves – A wave that do not require
a medium.

5. MECHANICAL WAVES
1. Transverse Wave – Is one in which the vibrations are at right angle or
perpendicular to the direction of the wave. Example: Rope
Crest – refer to the highest point of the
wave.
Trough – refers to the lowest point of
the wave.
Wavelength – The distance between
the two successive crest or trough,
Compressions or rarefactions
represented with the Greek letter
“lambda” (λ)
Amplitude – refers to the height of the
crest or the trough.

6. 2. Longitudinal Wave – Is one in which the vibrations are along the
direction of the wave. Example: Spring
Compressions – refer to the region
where the coil is pressed together.
Rarefactions – refers to the region
where the coils are spread.
Wavelength – The distance between
the two successive crest or trough,
Compressions or rarefactions
represented with the Greek letter
“lambda” (λ)

7. 3. Surface wave – Are combination of transverse and longitudinal
waves which occurs at the surface of two media such as water and
air. Example (Water wave)

8. Measurable Quantities of a Mechanical Wave:
Wavelength – The distance between the two successive crest or
trough, Compressions or rarefactions represented with the Greek
letter “lambda” (λ)
Amplitude – refers to the height of the crest or the trough.
Frequency – is the number of waves that pass a particular point
point every one second. The unit of frequency is Hertz (Hz

9. Number of Waves Time(seconds) Frequency(Hz)
50 5 10 Hz
10 10 1 Hz
100 10 10 Hz
Period – is the time required for one complete wave to pass a given
point. The formula of period is:
𝑃𝑒𝑟𝑖𝑜𝑑 = 1/ 𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐y
Frequency(Hz) Period(seconds)
2 Hz ½ or 0.5 second
10 Hz 1/10 or 0.1 second

10. Wave Speed – The distance travelled by the wave per second
𝑊𝑎𝑣𝑒 𝑆𝑝𝑒𝑒𝑑 = 𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦 𝑋 𝑊𝑎𝑣𝑒𝑙𝑒𝑛𝑔th
Frequency Wavelength(meters) Speed(meters/second)
10 5 50 meters/seconds
100 10 1000 meters/seconds

11. 2. Electromagnetic Wave