Unit: wave phenomenaYear: 1989 Question#: 51
Question: The diagram below represents straight wave fronts approaching an opening in a barrier
(1 )
(2
) 
3
) 
(4
) 
What is this question really asking?
Explanation by: Meghan K.
[ Return to question menu ]
Answer 1
Incorrect
This choice would be incorrect because it would mean that after the waves traveled through the barrier they continued in the path that they were in before going through the opening. What really happens is that the waves spread out behind each barrier, which this diagram does not show. return to top
Answer 2
Incorrect
If the waves had traveled through the opening from the other side this diagram would be correct. But, the definition of diffraction tells us that a wave spreads out in the opposite direction when traveling through an opening. return to top
Answer 3
Incorrect
When waves pass through an opening between barriers they are diffracted. This means that they will spread out behind the barriers to both the left and the right. This choice does not illustrate diffraction. return to top
Answer 4
Correct
The idea of diffraction tells us that waves will move in the manner shown in this diagram when overcoming an obstacle such as the opening in the barriers. The waves will spread out to the right behind the right barrier and to the left behind the left barrier. return to top
What's this question really asking?
How will waves act when passing through an opening between two barriers? (Diffraction) return to top
