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) Polarization

B) Constructive interference

C) Diffraction

D) Destructive interference

2 / 29

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

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

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

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

D) $\mathbf{\pi}$

3 / 29

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

A) Equal to one wave amplitude

B) Half the amplitude of each wave

C) Twice the amplitude of each wave

D) Equal to zero

4 / 29

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

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

B) $\mathbf{0}$

C) $\mathbf{2\pi}$

D) $\mathbf{\pi}$

5 / 29

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

A) Double the original amplitude

B) Maximum

C) Equal to the wavelength

D) Zero

6 / 29

Which condition produces constructive interference?

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

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

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 $\mathbf{= 2n\lambda}$

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

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

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

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) $\mathbf{5\ cm}$

C) $\mathbf{10\ cm}$

D) $\mathbf{0\ cm}$

9 / 29

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

A) $\mathbf{0\ cm}$

B) $\mathbf{12\ cm}$

C) $\mathbf{1\ cm}$

D) $\mathbf{7\ cm}$

10 / 29

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

A) Refraction

B) Reflection

C) Constructive interference

D) Destructive interference

11 / 29

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

A) Polarization

B) Constructive interference

C) Destructive interference

D) Maximum intensity

12 / 29

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

A) Random interference

B) Destructive interference

C) Constructive interference

D) No interference

13 / 29

Two waves interfere destructively. Which statement is correct?

A) Their displacements oppose each other.

B) Their frequencies become zero.

C) Their amplitudes always become zero.

D) Their wavelengths become different.

14 / 29

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

A) Minimum

B) Zero

C) Constantly changing

D) Maximum

15 / 29

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

A) Unchanged

B) Infinite

C) Minimum

D) Maximum

16 / 29

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

A) Decreased loudness

B) No sound due to absorption

C) Increased frequency

D) Increased loudness

17 / 29

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

A) Meet crest with crest and trough with trough

B) Meet crest with trough

C) Have different frequencies

D) Meet randomly

18 / 29

Destructive interference occurs when:

A) Crest overlaps with trough

B) Crest overlaps with crest

C) Both waves stop moving

D) Trough overlaps with trough

19 / 29

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

A) Destructive

B) Random

C) Impossible

D) Constructive

20 / 29

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

A) No interference

B) Constructive

C) Destructive

D) Polarized

21 / 29

Which comparison between constructive and destructive interference is correct?

A) Both always cancel waves.

B) Constructive increases amplitude, destructive decreases amplitude.

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

D) Both always increase 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) Minimum to maximum

C) Zero to maximum only

D) Constant value

23 / 29

When two waves interfere constructively, their energy:

A) is destroyed

B) disappears completely

C) converts into matter

D) is redistributed to form regions of higher intensity

24 / 29

Which statement correctly differentiates constructive and destructive interference?

A) Both produce maximum amplitude.

B) Both require different frequencies.

C) Constructive increases amplitude, destructive reduces amplitude.

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

25 / 29

A point where two waves cancel completely is called:

A) Wavelength point

B) Node

C) Crest

D) Antinode

26 / 29

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

A) Equilibrium point

B) Node

C) Antinode

D) Reflection point

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

B) $\mathbf{0\ cm}$

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

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

28 / 29

Which change can convert constructive interference into destructive interference?

A) Increasing amplitude only

B) Changing medium only

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

D) Increasing wavelength only

29 / 29

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

A) Coherent waves

B) Mechanical waves

C) Stationary waves

D) Transverse waves

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