(i) The elevated portions are called crests. The depressed portions are called troughs

(ii) A, C, E, G, I, K, M

(iii) 4 crests, and 3 troughs.

(iv) No

(v) E, I, M

(vi) G, K

(vii) Wavelength = 4 m

Characteristics of Waves:

1. Amplitude : Amplitude is the maximum displacement of a particle from its mean position. This is denoted by the letter a.

2. Wavelength: Wavelength is the distance between two consecutive particles which are in the same phase of vibration. This is equivalent to the distance advanced by the wave by the time a particle has completed one vibration. The Greek letter X (lambda) is used to denote the wavelength. The unit is metre (m).

3. Frequency: Frequency is the number of vibrations in one second.

Frequency = \(\frac{number\,of\,vibrations}{Time\,taken}f=\frac{n}{t}\)

The unit of frequency is hertz (Hz).

(viii) Frequency of the wave = \(\frac{number\,of\,vibrations}{Time}\)

\(f=n/t=\frac{100}{5}=20\)Hz

The equation connecting velocity, wavelength, and frequency of a wave is v = f λ ;

v – Velocity (distance travelled by the wave in one second);

f – frequency (number of vibrations in one second);

x – wavelength (distance between two consecutive particles which are in the same phase of vibration).