If a wave speeds up as it crosses a boundary, what happens to its wavelength?

The wavelength increases. Since $v = f\lambda$ and $f$ is constant, an increase in $v$ must be balanced by an increase in $\lambda$.

What property of a wave determines its color, and does this change during refraction?

Frequency determines color. Since frequency does not change during refraction, the color of light remains the same when it passes through different media.

Define 'Refraction' in terms of wave behavior.

Refraction is the change in direction of a wave caused by its change in speed as it moves from one medium to another.

How does the angle of incidence compare to the angle of reflection?

The angle of incidence is always equal to the angle of reflection ($i = r$). Both angles are measured between the ray and the normal line.

What is the 'normal' in a wave diagram?

The normal is an imaginary line drawn perpendicular ($90^{\circ}$) to the boundary surface at the point of incidence. It serves as the reference point for measuring all wave angles.

What happens to the frequency of a wave as it refracts into a different medium?

The frequency remains constant. Frequency is determined by the wave source and does not change when the wave enters a new material, even if speed and wavelength do.

When a wave moves from deep water to shallow water, how does its speed and wavelength change?

Both the speed and the wavelength decrease. Because the frequency stays the same, the reduction in speed must result in a shorter wavelength ($v = f\lambda$).

In which direction does light bend when moving from air into a denser medium like glass?

The light bends towards the normal. This occurs because light travels slower in glass than in air, causing the wavefronts to pivot toward the perpendicular line.

What is the difference between reflection and refraction regarding the medium?

In reflection, the wave stays within the original medium after hitting a boundary. In refraction, the wave passes through the boundary and enters a second medium.

How does the bending of a wave differ when it hits a boundary at $0^{\circ}$ vs. an acute angle?

At $0^{\circ}$ (along the normal), the wave changes speed but does not change direction. At an acute angle, the wave changes both speed and direction (refracts).

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Referral & Rewards

1. Electricity, Energy & Waves

Reflection & Refraction of Waves

Summary

Reflection and refraction are fundamental wave behaviors occurring at boundaries between different media. Reflection involves a wave bouncing back into its original medium, while refraction involves a change in wave speed and direction as it enters a new medium, governed by the relationship between speed, wavelength, and the angle of approach.

1. Definition & Core Concepts

Reflection occurs when a wave encounters a boundary between two media and is redirected back into the original medium rather than passing through.
Refraction is the change in direction of a wave as it crosses a boundary into a medium where its speed changes, such as light moving from air into glass or water waves moving from deep to shallow water.
The Normal is an imaginary line drawn perpendicular ( $90^{\circ}$ ) to the boundary surface at the point where the wave hits; all angles are measured relative to this line.
The Angle of Incidence ( $\theta_i$ ) is the angle between the incoming ray and the normal, while the Angle of Reflection ( $\theta_r$ ) or Angle of Refraction ( $\theta_R$ ) is the angle between the outgoing ray and the normal.

Diagram showing reflection and refraction at a boundary. An incident ray hits the boundary, producing a reflected ray at the same angle and a refracted ray bending towards the normal in the denser medium.

2. Underlying Principles

3. Methods & Techniques

4. Key Distinctions

5. Exam Strategy & Tips

6. Common Pitfalls & Misconceptions