# Physics equations/27-Wave Optics/Q:interference

This is version A only. Lint errors force the removal of other versions. See special:permalink/2159962

## pe27interference A

1 Two narrow slits are separated by 0.8 mm. The 15-th fringe appears 89 mm from the center of the diffraction pattern, and the screen is 9 m from the slits. What is the wavelength?

 a) 3.16E+02 nm b) 3.59E+02 nm c) 4.08E+02 nm d) 4.64E+02 nm e) 5.27E+02 nm

2 An isotropic sound source is placed at the origin, and another one is placed at x=0.69m and y= 0.71m. A microphone is placed at x=4.9m and y=4.1m. The amplitude of each source is adjusted so that the microphone reads the same intensity,for either source if the other source is turned off. When each source is sounded alone (without the other source), the amplitude is Acos(ωt+φ), where A=8.9. If the wavelength is 0.29m, what is the amplitude when both sources are turned on?

 a) 1.39E+01 b) 1.58E+01 c) 1.80E+01 d) 2.04E+01 e) 2.32E+01

3

The minima of single slit diffraction can be calculated using the drawing shown. If the path lengths from A and B cancel, then the same cancellation will occur throughout the slit, with each point between A and B being cancelled by a corresponding point between B and C. If the slit is 81 micrometers wide, and the wavelength is 2.8 micrometers, at what angle does the first minimum occur for single slit diffraction?

 a) 1.53E+00 degrees b) 1.74E+00 degrees c) 1.98E+00 degrees d) 2.25E+00 degrees e) 2.56E+00 degrees