# Waves, Sound and Light: Light Waves

## Light Waves: Audio Guided Solution

#### Problem 22:

In a museum exhibit, monochromatic red light (λ = 648 nm) passes through a double slit and is projected onto a screen located 16.8 m from the slits. A metric ruler located above the interference pattern clearly shows the fifth dark fringe to be located 42.0 cm from the central bright spot. Determine the slit separation distance.

## Audio Guided Solution

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## Habits of an Effective Problem Solver

• Read the problem carefully and develop a mental picture of the physical situation. If necessary, sketch a simple diagram of the physical situation to help you visualize it.
• Identify the known and unknown quantities and record in an organized manner, often times they can be recorded on the diagram itself. Equate given values to the symbols used to represent the corresponding quantity (e.g., v = 3.00x108 m/s, λ = 554 nm, f = ???).
• Use physics formulas and conceptual reasoning to plot a strategy for solving for the unknown quantity.
• Identify the appropriate formula(s) to use.
• Perform substitutions and algebraic manipulations in order to solve for the unknown quantity.