Question

When a wave travels from a denser to rarer medium

• A. speed of wave increases
• B. wave length of wave decreases
• C. amplitude of wave increases
• D. there is no change in phase angle

Answer 1

Answer: (A), (C), (D)

The correct options are
A speed of wave increases
C amplitude of wave increases
D there is no change in phase angle

Since the body moves from a denser to rarer medium, the velocity must increase.
To keep power transmission a constant, the amplitude of the wave would also increase.
Since $v=f\lambda$ and frequency being a property of the source (cannot change with medium), the wavelength must also increase.
There would also be no phase change. (only superimposition changes the phase).