Physics Waves NUMS 2020
PMDC Verified Question 94 of 125
Trough of a wave acts as:
A
Concave lens
B
Convex lens
C
Convex mirror
D
Plane mirror
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Concave lens
Concept:

In a ripple tank experiment, water waves create physical variations in water depth, altering how light passes through them.

Solution:

  • A wave crest acts like a bulging, converging structure, akin to a convex lens. This focuses overhead light, creating bright bands on the screen below.


  • Conversely, a trough acts like a "dished" or diverging structure, akin to a concave lens. Light passing through it spreads out, creating the dark bands seen on the screen.


Why other options are incorrect:

Convex lenses correspond to crests. Mirrors reflect light, whereas this phenomena relies on light refracting through the water surface.

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