Question

1. A radio wave interferometer contains two 10 m long arms, one of which can be lengthened to a maximum of 18.5 m. mirror 10.0 in radio waves - beamsplitter mirror -- -----> -85 detector (a) What is the longest radio wave where the interferometer can be adjusted from construc- tive to completely destructive interference? (b) I radio waves of wavelength 500 cm are sent into the interferometer, how many fringes pass by the detector while the adjustable arm changes from its smallest to largest dis- I d ents diffraction train screen

Answer 1

MAXIMUM POSSIBLE CHANGE IN PATH OF ONE OF BEAMS = 2 * INCREASE IN LENGTH - 2 x 8.5 m = 12 m _ CHANGE IN PATH LENGTH TO ADUS ADJUST SETTING FROM CONSTRUCTIVE TO DESTRUCTIVE INTERFERENCE = (2N-1) 1 [n- INTEGER] - 2 (2N-1) I } = 17 m FOR LARGEST VALUE OF x N SHOULD BE MINIMUM . N = 1 . LONGEST - 17 m . a LONGEST = 34 m b) FOR BY . = 'n' NUMBER OF FRINGEG PASSING DETECTOR nx = MAXIMUM CHANGE IN PATH = 17 m 17m 17 m - 3.4 = = 5m HENCE NUMBER IS