IB PhysicsTheme C--Paper2-Qc#6-7 Double slits- Energy of a wave

Qc-1 Red laser light is incident on a double slit with a slit separation of 0.35 mm.
A double-slit interference pattern is observed on a screen 2.4 m from the slits. The distance between successive maxima on the screen is 4.7 mm.
Calculate the wavelength of the light. Give your answer to an appropriate number of significant figures.
c. Explain the change to the appearance of the interference pattern when the red-light laser is replaced by one that emits green light.
d. One of the slits is now covered. Describe the appearance of the pattern on the screen
Qc-2
A student is investigating a method to measure the mass of a wooden block by timing the period of its oscillations on a spring.
Describe the conditions required for an object to perform simple harmonic motion (SHM).
A 0.52 kg mass performs simple harmonic motion with a period of 0.86 s when attached to
the spring. A wooden block attached to the same spring oscillates with a period of 0.74 s.
b. Calculate the mass of the wooden block.
c. In carrying out the experiment the student displaced the block horizontally by 4.8 cm from
the equilibrium position. Determine the total energy in the oscillation of the wooden block.
d. A second identical spring is placed in parallel and the experiment in (b) is repeated.
Suggest how this change affects the fractional uncertainty in the mass of the block.

Topic 4 and topic 9 oscillations and waves-playlist: