A laser beam with wavelength \(633 \mathrm{nm}\) is split into two beams by a beam splitter. One beam goes to Mirror \(1,\) a distance \(L\) from the beam splitter, and returns to the beam splitter, while the other beam goes to Mirror \(2,\) a distance \(L+\Delta x\) from the beam splitter, and returns to the same beam splitter. The beams then recombine and go to a detector together. If \(L=1.00000 \mathrm{~m}\) and \(\Delta x=1.00 \mathrm{~mm},\) which best describes the kind of interference at the detector? (Hint: To doublecheck your answer, you may need to use a formula that was originally intended for combining two beams in a different geometry, but which still is applicable here.) a) purely constructive b) purely destructive c) mostly constructive d) mostly destructive e) neither constructive nor destructive

Short Answer

Expert verified
Answer: (c) mostly constructive

Step by step solution

01

Understand the Concepts of Constructive and Destructive Interference

Constructive interference occurs when two waves add up to create a larger wave. It occurs when the difference in the path lengths is an integer number of wavelengths. Destructive interference occurs when two waves cancel each other out, resulting in a smaller wave or zero amplitude. It happens when the difference in the path lengths is an odd-integer (odd multiple) of half wavelengths.
02

Calculate the Path Length Difference

Calculate the path length difference ΔL to determine the difference in distance between the two beams. ΔL = 2Δx = 2 × 1.00 mm = 2.00 mm
03

Convert All Distances to the Same Unit and Calculate Number of Wavelengths in ΔL

Convert all distances to the same unit (meters) and calculate the number of wavelengths in the path length difference. lambda = 633 nm = 633 x 10^{-9} m ΔL = 2.00 mm = 2.00 x 10^{-3} m Number of wavelengths in ΔL = ΔL / lambda = (2.00 × 10^{-3}) / (633 × 10^{-9}) = 3162.39
04

Determine Interference Type

Now, we'll determine the interference type based on the number of wavelengths in the path length difference. Since 3162.39 is very close to an integer value (3162), the interference will be mostly constructive. Therefore, the correct answer is (c) mostly constructive.

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Most popular questions from this chapter

For a double-slit experiment, two 1.50 -mm wide slits are separated by a distance of \(1.00 \mathrm{~mm} .\) The slits are illuminated by a laser beam with wavelength \(633 \mathrm{nm} .\) If a screen is placed \(5.00 \mathrm{~m}\) away from the slits, determine the separation of the bright fringes on the screen.

What would happen to a double-slit interference pattern if a) the wavelength is increased? b) the separation distance between the slits is increased? c) the apparatus is placed in water?

What is the wavelength of the X-rays if the first-order Bragg diffraction is observed at \(23.0^{\circ}\) related to the crystal surface, with inter atomic distance of \(0.256 \mathrm{nm} ?\)

Some mirrors for infrared lasers are constructed wit alternating layers of hafnia and silica. Suppose you want to produce constructive interference from a thin film of hafnia \((n=1.90)\) on BK-7 glass \((n=1.51)\) when infrared radiation of wavelength \(1.06 \mu \mathrm{m}\) is used. What is the smallest film thickness that would be appropriate, assuming the laser beam is oriented at right angles to the film?

The Michelson interferometer is used in a class of commercially available optical instruments called wavelength meters. In a wavelength meter, the interferometer is illuminated simultaneously with the parallel beam of a reference laser of known wavelength and that of an unknown laser. The movable mirror of the interferometer is then displaced by a distance \(\Delta d,\) and the number of fringes produced by each laser and passing by a reference point (a photo detector) is counted. In a given wavelength meter, a red He-Ne laser \(\left(\lambda_{\mathrm{Red}}=632.8 \mathrm{nm}\right)\) is used as a reference laser. When the movable mirror of the interferometer is displaced by a distance \(\Delta d\), a number \(\Delta N_{\text {Red }}=6.000 \cdot 10^{4}\) red fringes and \(\Delta N_{\text {unknown }}=7.780 \cdot 10^{4}\) fringes pass by the reference photodiode. a) Calculate the wavelength of the unknown laser. b) Calculate the displacement, \(\Delta d\), of the movable mirror.

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