Why Is It So? Season 3, Episode 4: Resonance – Forced Vibrations

Waves: Kinds and Properties

""What is a wave?"" is a simple question that is not easy to answer. Miller wishes to answer the question by showing different kinds of waves. But it is the class of acoustic waves that will be the major subject of the next six programs.

Sound Waves – Sources of Sound

For sound to be heard, there has to be something to compress. Miller vibrates metal, tears cloth, and blows streams of air through holes to discuss the propagation of sound waves.

Vibrating Bars & Strings – The Phenomenon of Beats

Miller excites musical bars and tuning forks to demonstrate beats, a disruptive musical aspect. When he holds a vibrating bar at the nodes, the bar still vibrates. And he holds a vibrating string to demonstrate harmonics and overtones.

Sounding Pipes

Miller excites pipes by driving air through them and heating them. The most enchanting element comes from heating pipes with wire screens lodged in them. He calls it ""filling them with music."" The physics of thermally excited pipes is difficult to understand, but a joy to hear.

Vibrating Rods and Plates

Miller strikes rods at the beginning of the program, creating different nodes depending on where he holds the bar. Then comes his artistic masterpiece: vibrating plates sprinkled with sand and bowed with a bow. Wonderful artistic designs result from that bowing.

Miscellaneous Adventures in Sound

Miller has set up a Blackburn pendulum. At its bottom is a funnel which he fills with salt and lets go at a certain position. The funnel swerves around, and the falling sand produces Lissajous figures.

Electrostatic Phenomena: Foundations of Electricity

From a simple observation of attraction between a charged rod and small bits of matter, comes all our knowledge of electrostatics and electricity. Miller charges objects by conduction and induction.

Adventures with Electric Charges

The Van Der Graaf Generator is the focus of this program. Miller sets up an astonishing set of demonstrations, such as the ""Mad Professor's Hair.""

Adventures in Magnetism

Everything is magnetic to more or less degree, says Miller. He suggests making an iron bar a magnet just by aligning it properly and striking it at one end. Then he introduces the electromagnet. And just how strong is a magnetic force? It's a puzzler.

Ways to Produce Electricity

One does not produce electricity. It is abundant around us. Miller simply shows ways electricity can be seen or do work. Miller makes a voltaic cell, explaining that lead plates in storage batteries are not all lead. He also sheds light (literally) on electromagnetic induction.

Properties and Effects of Electric Currents

Miller reproduces Hans Christian Oersted's experiment that showed electricity produces magnetism. Then Miller also copper-plates a small lead slab in a solution of copper sulfate amd cooks a hot dog on an electric system.

Adventures in Electromagnetism

Miller reproduces Faraday's experiment that led to electromagnetic induction. More powerful is the experiment on an electric charge.

Further Adventures in Electromagnetism

Miscellaneous and Wondrous Things in E & M

Mars Landing 2012: The New Search for Life

Mars Landing 2012: The New Search for Life provides detailed coverage of NASA’s incredible Curiosity rover and its recent landing on the surface of Mars. The mission: to search for evidence of past or present Martian life. This one-hour special will focus on the science and the technology involved to bring this mission to fruition using a combination of field reporting, hosted interviews and informed news updates. We’ll have scientists, technicians and big picture thinkers — those who have dedicated their careers and passion to this project.