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Part 4 of the HeNe Laser lab. For a laser cavity to be stable, the light must be able to make many round trips through the gain medium without escaping. By changing the spacing of the mirrors, we go from a stable cavity configuration to an unstable one.

Part 2 of the HeNe Laser lab. Usually a laser is adjusted to produce just the lowest order or Gaussian mode. By using a tube with a wider-than-normal inside diameter and adjustable mirrors, we can observe some of the higher-order modes.

Part 3 of the HeNe Laser lab. Once the laser is oscillating in a 2-lobe pattern, we use a double slit to investigate the phase relationship between the two lobes. If the lobes are in phase with each other, the double-slit pattern should have a central maximum, and if they are out of phase it should have a central minimum.

Part 1 of the HeNe laser lab. A laser consists of a gain medium, where light can be amplified by stimulated emission, and mirrors to form a cavity where light can be bounced back and forth through the gain medium. Initially, the laser gain tube has glass windows mounted at Brewster's angle (to eliminate reflective losses for one light polarization) but no mirrors. External mirrors are added to ...

Demonstrating surface tension with a loop of thread. A loop of thread is floating on the surface of a bowl of water. The surface tension inside and outside of the loop are the same, and the loop is limp. But what happens if I put a drop of soap inside the loop? The surface tension inside the loop decreases, but the surface tension outside is initially unchanged. There's an unbalanced force pull...

The Tesla coil produces high-frequency pulses using driven resonant circuits and transformers. These pulses are very short, like a "click," and can be switched on and off electronically. If it is set to produce 400 pulses per second, for example, your ear perceives this as a 400 Hz tone, and not just a series of clicks. The coil can be programmed to play back a recorded tune, or connected to a ...

A Galton machine drops particles onto a series of pins, where the particle can fall either to the left or the right at each pin. After encountering several layers of pins, the particles are collected in bins at the bottom. The distribution of the particles approximates a Normal (Gaussian) Distribution.

A cloud chamber containing cooled alcohol vapor shows trails of microscopic alcohol droplets condensing along the paths of charged subatomic particles. The radioactive source is the isotope Pb-210 painted onto a needle, generating both alphas (fat trails) and betas (thin trails).

Four rubber balls are stacked on top of a pizza pan, placed directly over four water glasses. When the pizza pan is given a sideways shove, it moves sideways, but the balls remain still because of their inertia. High-speed video captures the result in slow motion.

A glass is excited at resonance using sound waves. High-speed video shows the distortion of the glass. The amplitude of the motion grows until the glass shatters violently.

When air is rapidly compressed it heats up. In this case, the air is heated enough to ignite some cotton fibers in the bottom of the tube.

A piston in a tight-fitting tube bounces adiabatically on a trapped volume of air.

A metal plate is sprinkled with sand and driven with a speaker at the center. The sand collects on the parts of the plate that aren't moving, displaying a 2-dimensional standing wave pattern.

Standing waves on a string fixed at both ends. Resonance occurs when the round trip distance 2L is an integer number of wavelengths. Strobe lighting is used to slow down the motion of the string to make it visible.

Ultrasonic Levitation

Soap Film

Wine Glass

Time Domain Measurement

Shorter Laser

Finesse Measurement

Drifting Modes & Gain Curve

Fabry-Perot Scan Features

Fabry-Perot Introduction

Faraday Effect (AC)

Faraday Effect (DC)

Faraday Effect

Optical Activity

Reflectivity

Brewster's Angle