Page 223 - text book form physics kssm 2020

Chapter 5
Waves
3. From Pattern 1 and Pattern 2: 5.6.3
(a) Determine the constant variable.
(b) What is the relationship between x and a?
4. From Pattern 2 and Pattern 3:
(a) Determine the constant variable.
(b) Compare the wavelength, λ.
(c) What is the relationship between x and λ?
5. From Pattern 3, determine the relationship between x and D.

In the pattern of interference of water, sound and light waves, variables λ, a, x and D are
mutually dependent on one another. Th rough Activity 5.21, we can interrelate the four variables
λD
as x = . From the formula, we can determine the wavelength, λ as follows:
a
ax
λ =
D

Solving Problems Involving Interference of Waves

Example 1

Figure 5.65 shows Young’s double- Young’s double-slit Transparent screen
slit experiment which produces a = 0.4 mm
interference pattern on the screen.
Th e distance between adjacent Bright fringe
bright fringes is 4.5 mm. What is the Dark fringe
wavelength of the light used? x = 4.5 mm
Light source

Solution:
D = 3.0 m
Separation of slit, a = 0.4 mm
Figure 5.65 Young’s double-slit experiment
= 0.4 × 10 m
–3
Distance between adjacent bright fringes, x = 4.5 mm
= 4.5 × 10 m
–3
Distance between screen and double slit, D = 3.0 m

ax
Wavelength, λ =
D
–3
–3
(0.4 × 10 )(4.5 × 10 )
=
3.0
= 6.0 × 10 m
–7
5.6.3 5.6.4

217
217
5.6.3 5.6.4
5.6.4
5.6.3