8 Wave Optics Free Online FlashCards

What kind of wave is light?

Light is a transverse electromagnetic wave: its electric and magnetic fields oscillate perpendicular to each other and to the direction of travel.

What happens to light’s frequency when it enters a material?

When light enters a material, its speed and wavelength change, but its frequency remains the same.

What determines the intensity pattern when light waves overlap?

Interference occurs when overlapping light waves combine: their electric fields add by superposition, and the resulting intensity depends on their phase difference.

How is path difference related to angle in Young’s double-slit experiment?

In Young’s double-slit experiment, the path difference is approximately $\Delta\ell = d\sin\theta$, where $d$ is slit separation and $\theta$ is the angle from the central direction.

When is diffraction most pronounced?

Diffraction is the spreading of a wave as it passes through an opening or around an obstacle. It is most pronounced when the opening or obstacle is comparable in size to the wavelength.

What condition gives dark fringes in single-slit diffraction?

For a single slit of width $a$, dark fringes occur where $a\sin\theta = m\lambda$, for nonzero integer $m$.

What does a polarizing filter transmit, and why can’t sound in air be polarized?

A polarizing filter transmits the electric-field component parallel to its transmission axis and blocks the perpendicular component. Sound in air is longitudinal, so it cannot be polarized this way.

How are light’s speed, frequency, and wavelength related in a vacuum?

In a vacuum, light’s speed, frequency, and wavelength are related by $c = f\lambda$.

What makes waves coherent, and why does it matter?

Coherent waves have the same frequency and a steady phase relationship; this is required for stable interference fringes.

What path differences produce bright and dark double-slit fringes?

Bright fringes occur when $\Delta\ell = m\lambda$; dark fringes occur when $\Delta\ell = (m + \frac{1}{2})\lambda$, for integer $m$.

How is bright-fringe spacing estimated for a distant screen?

For a distant screen, adjacent bright-fringe spacing is approximately $\Delta y = \frac{\lambda D}{d}$, where $D$ is screen distance and $d$ is slit separation.

How does the central maximum compare with side maxima?

The central bright maximum lies between the first minima and is wider and brighter than the side maxima. Narrower slits produce wider diffraction patterns.