Question 1
A student attempts to show the
interference of light using two identical green LEDs.
Which statement explains why the
experiment will not succeed?
A The light waves from the sources
are not coherent.
B The light waves from the sources
do not have the same amplitude.
C The light waves from the sources
have a range of wavelengths.
D The light waves from the sources
are not monochromatic.
Reference: Past Exam Paper – June 2014 Paper 13 Q28
Solution 1:
Answer: A.
Interference occurs when the light
waves are coherent (that is, they have constant phase difference and the same
frequency). So, if they light waves from the sources are not coherent, the
experiment will not succeed.
Amplitude is not a condition for
interference.
Since the LEDs are identical, they
are monochromatic and have the same wavelength.
