Diffraction and diffraction gratingsEdexcel A-Level Physics: Mind map

Exam questions on Diffraction and diffraction gratings

1. In a ripple tank, a vibrating dipper produces plane water waves of wavelength 1.5 cm that travel towards two barriers with an adjustable gap between them. The speed of the waves in the tank is constant, and the frequency of the dipper can be changed.
   Use Huygens' construction to explain why the waves spread into the region behind the edges of the barriers.2 marks
2. A student shines a red laser of wavelength 633 nm at normal incidence onto a diffraction grating with 600 lines per millimetre. A series of bright spots is seen on a distant screen, either side of a central bright spot.
   Calculate the angle between the central maximum and the first-order maximum.2 marks
3. In a core practical, a student determines the wavelength of light from a laser using a diffraction grating with 300 lines per millimetre. The grating is held perpendicular to the beam and the screen is 1.00 m from it. The student measures the distance between the two second-order maxima, one on each side of the central maximum, as 0.850 m.
   Calculate the wavelength of the laser light.3 marks