Interference and Young's double-slit experimentAQA A-Level Physics: Mind map

Exam questions on Interference and Young's double-slit experiment

1. Two loudspeakers are connected to the same signal generator, so they emit sound of the same wavelength, 0.50 m, in phase with each other. A listener stands at a point P that is 4.00 m from one loudspeaker and 4.75 m from the other.
   The two loudspeakers are now connected to two separate signal generators, each set to emit nominally the same frequency. Explain why the listener no longer hears a stable pattern of loud and quiet positions.2 marks
2. A student shines light from a laser of wavelength 650 nm at a pair of narrow parallel slits whose centres are 0.40 mm apart. A fringe pattern forms on a screen 2.5 m from the slits.
   Explain why a laser must never be viewed directly along the beam, and state one other precaution the student should take.2 marks
3. A student measures the wavelength of the light from a laser pointer using a double slit with a slit separation of 0.30 mm. The screen is 2.00 m from the slits. She measures the distance across ten fringe spacings on the screen as 46 mm.
   Calculate the wavelength of the laser light.3 marks