Physics 11th Chap 9 : Topic 8 - Maryam Publications

Physics Chapter 9 : Topic 8

Constructive and Destructive Interference

1 / 29

When two waves meet and their displacements add together to produce a wave of greater amplitude, the phenomenon is called:

A) Destructive interference

B) Constructive interference

C) Polarization

D) Diffraction

2 / 29

Constructive interference occurs when the phase difference between two waves is:

A) $\mathbf{\pi\ /\ 2}$

B) $\mathbf{2n\pi}$

C) $\mathbf{(2n + 1)\ \pi}$

D) $\mathbf{\pi}$

3 / 29

Two waves of equal amplitude interfere constructively. The resultant amplitude will be:

A) Equal to zero

B) Twice the amplitude of each wave

C) Equal to one wave amplitude

D) Half the amplitude of each wave

4 / 29

Destructive interference occurs when two waves have a phase difference of:

A) $\mathbf{0}$

B) $\mathbf{\pi}$

C) $\mathbf{2\pi}$

D) $\mathbf{\pi\ /\ 2}$

5 / 29

In destructive interference between two waves of equal amplitude, the resultant amplitude is:

A) Equal to the wavelength

B) Maximum

C) Double the original amplitude

D) Zero

6 / 29

Which condition produces constructive interference?

A) Path difference $\mathbf{= 3\lambda\ /\ 4}$

B) Path difference $\mathbf{= \lambda\ /\ 4}$

C) Path difference $\mathbf{= n\lambda}$

D) Path difference $\mathbf{= (2n + 1)\ \lambda\ /\ 2}$

7 / 29

The condition for destructive interference is:

A) Path difference $\mathbf{=}$ zero

B) Path difference $\mathbf{= 2n\lambda}$

C) Path difference $\mathbf{= (2n + 1)\ \lambda\ /\ 2}$

D) Path difference $\mathbf{= n\lambda}$

8 / 29

Two waves have amplitudes $\mathbf{5\ cm}$ and $\mathbf{5\ cm}$. If they interfere destructively, the amplitude of the resultant wave is:

A) $\mathbf{2.5\ cm}$

B) $\mathbf{0\ cm}$

C) $\mathbf{5\ cm}$

D) $\mathbf{10\ cm}$

9 / 29

Two waves of amplitudes $\mathbf{4\ cm}$ and $\mathbf{3\ cm}$ interfere destructively. The resultant amplitude will be:

A) $\mathbf{7\ cm}$

B) $\mathbf{12\ cm}$

C) $\mathbf{1\ cm}$

D) $\mathbf{0\ cm}$

10 / 29

The bright fringes observed in Young’s double-slit experiment are due to:

A) Reflection

B) Refraction

C) Constructive interference

D) Destructive interference

11 / 29

The dark fringes in Young’s double-slit experiment are formed because of:

A) Maximum intensity

B) Constructive interference

C) Destructive interference

D) Polarization

12 / 29

If two coherent waves have zero phase difference, they will produce:

A) No interference

B) Destructive interference

C) Constructive interference

D) Random interference

13 / 29

Two waves interfere destructively. Which statement is correct?

A) Their frequencies become zero.

B) Their wavelengths become different.

C) Their displacements oppose each other.

D) Their amplitudes always become zero.

14 / 29

At a point of constructive interference, the intensity of light is:

A) Minimum

B) Zero

C) Maximum

D) Constantly changing

15 / 29

At a point of destructive interference, the intensity of light is:

A) Minimum

B) Maximum

C) Unchanged

D) Infinite

16 / 29

Two sound waves of the same frequency reach a point with a phase difference of $\mathbf{\pi}$. The listener experiences:

A) Increased frequency

B) Decreased loudness

C) No sound due to absorption

D) Increased loudness

17 / 29

Constructive interference between two waves requires that their crests and troughs should:

A) Have different frequencies

B) Meet randomly

C) Meet crest with trough

D) Meet crest with crest and trough with trough

18 / 29

Destructive interference occurs when:

A) Crest overlaps with trough

B) Trough overlaps with trough

C) Both waves stop moving

D) Crest overlaps with crest

19 / 29

If the path difference between two coherent waves is $\mathbf{\lambda}$, the interference will be:

A) Impossible

B) Constructive

C) Random

D) Destructive

20 / 29

If the path difference between two coherent waves is $\mathbf{\lambda\ /\ 2}$, the interference will be:

A) Polarized

B) Constructive

C) No interference

D) Destructive

21 / 29

Which comparison between constructive and destructive interference is correct?

A) Both always cancel waves.

B) Both always increase amplitude.

C) Constructive increases amplitude, destructive decreases amplitude.

D) Constructive gives minimum amplitude, destructive gives maximum amplitude.

22 / 29

Two waves with equal amplitude and frequency interfere. If their phase difference changes from $\mathbf{0}$ to $\mathbf{\pi}$, the resultant amplitude changes from:

A) Maximum to minimum

B) Zero to maximum only

C) Minimum to maximum

D) Constant value

23 / 29

When two waves interfere constructively, their energy:

A) is destroyed

B) converts into matter

C) is redistributed to form regions of higher intensity

D) disappears completely

24 / 29

Which statement correctly differentiates constructive and destructive interference?

A) Both require different frequencies.

B) Constructive occurs due to opposite phases, destructive due to same phases.

C) Both produce maximum amplitude.

D) Constructive increases amplitude, destructive reduces amplitude.

25 / 29

A point where two waves cancel completely is called:

A) Wavelength point

B) Crest

C) Antinode

D) Node

26 / 29

A point where two waves interfere constructively with maximum displacement is called:

A) Reflection point

B) Equilibrium point

C) Node

D) Antinode

27 / 29

If one wave has a displacement of $\mathbf{+ \ 6\ cm}$ and another has displacement of $\mathbf{- \ 6\ cm}$ at the same point, the resultant displacement is:

A) $\mathbf{+ \ 6\ cm}$

B) $\mathbf{0\ cm}$

C) $\mathbf{+ \ 12\ cm}$

D) $\mathbf{- \ 1}\mathbf{2\ cm}$

28 / 29

Which change can convert constructive interference into destructive interference?

A) Increasing amplitude only

B) Changing phase difference from $\mathbf{0}$ to $\mathbf{\pi}$

C) Changing medium only

D) Increasing wavelength only

29 / 29

Two waves having the same frequency and constant phase difference are called:

A) Mechanical waves

B) Coherent waves

C) Transverse waves

D) Stationary waves

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