8. Superposition
A section of Physics, 9702
Listing 10 of 295 questions
The variation with time t of the displacement y of a wave X, as it passes a point P, is shown in . –4.0 –3.0 –2.0 –1.0 1.0 2.0 \ / cm 3.0 4.0 1.0 2.0 3.0 4.0 5.0 W / ms ZDYH; The intensity of wave X is I. Use to determine the frequency of wave X. frequency = Hz A second wave Z with the same frequency as wave X also passes point P. Wave Z has intensity 2I. The phase difference between the two waves is 90°. On , sketch the variation with time t of the displacement y of wave Z. Show your working. A double-slit interference experiment is used to determine the wavelength of light emitted from a laser, as shown in . laser light double slit ' 0.45 mm screen (not to scale) The separation of the slits is 0.45 mm. The fringes are viewed on a screen at a distance D from the double slit. The fringe width x is measured for different distances D. The variation with D of x is shown in . 1.5 1.0 2.0 3.0 4.0 [ / mm 5.0 2.0 2.5 3.0 ' / m 3.5 Use the gradient of the line in to determine the wavelength, in nm, of the laser light. wavelength = nm The separation of the slits is increased. State and explain the effects, if any, on the graph of .
9702_s16_qp_21
THEORY
2016
Paper 2, Variant 1
View
Interference fringes may be observed using a light-emitting laser to illuminate a double slit. The double slit acts as two sources of light. Explain the part played by diffraction in the production of the fringes, the reason why a double slit is used rather than two separate sources of light. A laser emitting light of a single wavelength is used to illuminate slits S1 and S2, as shown in . laser screen light 2.4 m B A 0.48 mm S1 S2 (not to scale) An interference pattern is observed on the screen AB. The separation of the slits is 0.48 mm. The slits are 2.4 m from AB. The distance on the screen across 16 fringes is 36 mm, as illustrated in . 16 fringes 36 mm Calculate the wavelength of the light emitted by the laser. wavelength = m Two dippers D1 and D2 are used to produce identical waves on the surface of water, as illustrated in . D1 P D2 11.2 cm water 7.2 cm 7.2 cm (not to scale) Point P is 7.2 cm from D1 and 11.2 cm from D2. The wavelength of the waves is 1.6 cm. The phase difference between the waves produced at D1 and D2 is zero. State and explain what is observed at P. State and explain the effect on the answer to if the apparatus is changed so that, separately, 1. the phase difference between the waves at D1 and at D2 is 180°, 2. the intensity of the wave from D1 is less than the intensity of that from D2.
9702_s17_qp_22
THEORY
2017
Paper 2, Variant 2
View
For a progressive wave, state what is meant by wavelength. A light wave from a laser has a wavelength of 460 nm in a vacuum. Calculate the period of the wave. period = s The light from the laser is incident normally on a diffraction grating. Describe the diffraction of the light waves at the grating. A diffraction grating is used with different wavelengths of visible light. The angle θ of the fourth-order maximum from the zero-order maximum is measured for each wavelength. The variation with wavelength λ of sin θ is shown in . θ sin λ / nm The gradient of the graph is G. Determine an expression, in terms of G, for the distance d between the centres of two adjacent slits in the diffraction grating. d = On , sketch a graph to show the results that would be obtained for the second-order maxima.
9702_s21_qp_21
THEORY
2021
Paper 2, Variant 1
View
Light from a laser is used to produce an interference pattern on a screen, as shown in . light of wavelength 660 nm O P Q R 0.44 mm 1.8 m double slit screen central bright fringe dark fringe bright fringe dark fringe (not to scale) The light of wavelength 660 nm is incident normally on two slits that have a separation of 0.44 mm. The double slit is parallel to the screen. The perpendicular distance between the double slit and the screen is 1.8 m. The central bright fringe on the screen is formed at point O. The next dark fringe below point O is formed at point P. The next bright fringe and the next dark fringe below point P are formed at points Q and R respectively. The light waves from the two slits are coherent. State what is meant by coherent. For the two light waves superposing at R, calculate: the difference in their path lengths, in nm, from the slits path difference = nm their phase difference. phase difference = ° Calculate the distance OQ. distance OQ = m The intensity of the light incident on the double slit is increased without changing the frequency. Describe how the appearance of the fringes after this change is different from, and similar to, their appearance before the change. The light of wavelength 660 nm is now replaced by blue light from a laser. State and explain the change, if any, that must be made to the separation of the two slits so that the fringe separation on the screen is the same as it was for light of wavelength 660 nm.
9702_s22_qp_22
THEORY
2022
Paper 2, Variant 2
View
Questions Discovered
295