Test on Interference of waves

Question 1: Coherent wave sources are characterized by having different wavelengths but a constant phase relationship.

A. Yes

B. No

Explanation: For sources to be coherent, they must have the same frequency and wavelength, in addition to maintaining a constant phase relationship with each other.

Question 2: For destructive interference, the path difference between two waves must be an even integer multiple of half the wavelength.

A. Yes

B. No

Explanation: Destructive interference occurs when the path difference between the two waves is an odd integer multiple of half the wavelength (Δr = (2k + 1) · λ/2), not an even integer multiple of half the wavelength.

Question 3: According to the provided study materials, which statement accurately describes how energy is conserved during wave interference, despite the apparent changes in intensity?

A. Energy is destroyed at points of destructive interference and new energy is created at points of constructive interference.

B. The total energy across the entire interference pattern remains constant because energy from destructive interference regions is redistributed to constructive interference regions.

C. Energy is temporarily stored in the wave medium at points of destructive interference, to be released at constructive interference points.

D. Interference patterns are an exception to the law of energy conservation due to the superposition of waves.

Explanation: The study materials explicitly state: 'However, energy is always conserved. The energy that is 'missing' from destructive interference regions is simply redistributed to the regions of constructive interference, where the intensity is higher. The total energy across the entire interference pattern remains constant.'

Question 4: According to the provided study materials, if the wavelength of waves in an interference experiment is increased, how would the resulting interference pattern typically change?

A. The bright and dark fringes would appear closer together.

B. The pattern would become more compressed with narrower fringes.

C. The pattern would become more spread out with wider fringes.

D. The intensity of the central maximum would decrease significantly.

Explanation: The study materials state that 'Longer wavelengths will result in a more spread-out pattern with wider fringes, while shorter wavelengths will produce a more compressed pattern.' This demonstrates the direct proportionality between fringe spacing and wavelength (y_k ∝ λ). Therefore, increasing the wavelength causes the fringes to spread out and become wider.

Question 5: The calculation for the position of the first-order bright fringe from the central maximum results in 4400 × 10⁻³ m.

A. Yes

B. No

Explanation: According to the study materials, the calculation for the position of the first-order bright fringe results in 4400 × 10⁻⁶ m, which then simplifies to 4.4 × 10⁻³ m, not 4400 × 10⁻³ m.