1.11 Electromagnetic waves

1.11 Electromagnetic waves

(a) Electromagnetic waves consists of variation of the electric and magnetic components.

(b) All electromagnetic waves are transverse waves that travel at a constant speed of

in vacuum.

(c) All electromagnetic waves exhibit properties such as reflection, refraction, diffraction and interference.

(d) Electromagnetic spectrum.

1.10 Interference

1.10 Interference

(a) Interference is a phenomenon produced by superposition between two coherent waves. Coherent waves are waves with same frequency and having a constant phase difference.

1.9 Diffraction of waves

1.9 Diffraction of waves

(a) Diffraction is the spreading of wave round sharp edges when the wave encounters a small opening or small obstacle.

(b) Diffraction grating is a piece of transparent material with many parallel lines marked on it. The spaces between two lines act as slits. Diffraction occurs as light pass through the slits.

(c) Diffraction pattern.

The diffraction pattern is produced by a combination of diffraction and interference effect.

(d) Diffraction grating formula

1.8 Frequency range of sound wave

1.8 Frequency range of sound wave

1.7 Echo

1.7 Echo

(a) Echo is caused by the reflection of sound wave from a hard and rigid surface.

(b) Reflection of sound waves obey the laws of reflection of waves.

(c) Echo can only be detected if the distance between the sound source and the reflecting surface exceed 17 m.

(d) In using effect of echo to measure the depth of the sea, sonic pulses are emitted towards the seabed. The reflected sonic pulses are recorded. If total time taken = t

1.6 Comparison between sound waves and light wave

1.6 Comparison between sound waves and light wave

1.5 Refraction of water wave

1.5 Refraction of water wave

When water waves move from a deep region to a region of shallow water,

(a) the velocity, v decreases,

(b) wavelength decreases,

(c) frequency, f unchange.

1.4 Diffraction of water wave

1.4 Diffraction of water wave





(a) Diffraction is the spreading of wave round a sharp edge when the wave encounters a small opening or obstacle.(i) Small obstacle

Diffraction through an opening depends on the width, a, of the opening.

For wavelength > a, greater effect of diffraction and vice versa

1.3 Reflection of water wave

1.3 Reflection of water wave

Angle of incident = angle of reflection

1.2 Relation between v, f and wavelength

1.2 Relation between velocity v, frequency f andwavelength

1.1 Waves

1.1 Waves

(a) The period T, is the time taken to complete one vibration or oscillation.

The unit of T is seconds.

(b) Frequency f is the number of vibrations completed in one second.

The unit of f is hertz (Hz)

(c)

(d) Amplitude is the maximum displacement from the equilibrium position.

3. Examples of vibration or oscillation:

(b) Loading spring