Made by the Burton Holmes Films, Inc. during WWII, RCL Part One and Part Two are b&w educational films made to train Radio Technicians for the U.S. Navy. The film was number MN-1540c and officially referred to as “Resistance and Capacitance RCL” and described this way: “Current and voltage in relation to time. Voltage and current curves. How current and voltage leads current in different instances, and relation of current and voltage. Graphic methods measuring voltage at source, addition of phase components, and effect of impedance on resistance.” The film uses a variety of techniques to present information, including live action, animation, graphs, and combinations of live action and animation. It discusses capacitors, inductors, radio apparatus, alternating current, and, in part two, the addition of phase components, resonance and frequency, and impedance, and a demonstration of audio filtration is shown. Copyright is 1944.

Opening titles: United States Navy Training Film – Radio Technician Training Series RCL Part 1 (:06-:26). A man holds a capacitor, which is a device that stores electrical energy in an electric field. An Inductor is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it. A capacitor charge is explained and shown in a diagram. Condenser drained of its charge is explained. A current with a charge or a discharge is explained (:27-2:12). Charge and discharge currents. Recharge curve. A current in relation to time is shown via a diagram. Voltage in relation to time (2:13-4:04). Volts and amperes. Voltage increase, current decreases. Title: Voltage Curves and Current Curves. Battery voltage, current curve, condenser voltage (4:05-6:41). Alternating battery voltage graph, a line moves and is explained. A sine wave is explained and shown on an oscilloscope. A pendulum. A balance wheel of a watch (6:42-8:21). A sine wave sound is reproduced with a musical quality. Inductive circuit is explained and shown on a diagram. Capacitive circuit (8:22-10:04). Title: Phase relations of Current and Voltage. Sign graph shows voltage and current in phase. Different phases for current and voltage are explained (10:05-12:51). End credits (12:52-13:11).

Part 2 (13:12-13:20(: Addition of Phase Components. Different circuits are explained. OHMS, an ohm is the SI derived unit of electrical resistance. Volts are dropped and measured (13:21-15:25). Sine waves. A compass is used for writing and charting on the graph. A three and four volt sine wave. Ohms Law. Four volt peak (15:26-17:22). Hand uses a compass and writes on a graph. Voltage meter (17:23-18:32). Title: There is another method of adding out-of-phase voltages. A voltage cycle shown as a wheel. Resistance voltage. Inductive voltage leads resistance voltage is explained and shown. A line is drawn with a ruler (18:33-20:12). Sailor sits at a table using a ruler. A right angle is drawn. A straight line is then drawn and makes a triangle. Volt meter moves (20:13-22:07). A book is opened and it shows an example of the theorem of Pythagoras: the theorem attributed to Pythagoras shows that the square of the hypotenuse of a right triangle is equal to the sum of the squares of the other two sides. Impedance is the effective resistance of an electric circuit or component to alternating current, arising from the combined effects of ohmic resistance and reactance (22:08-23:55). IZ squared + IR squared + IX squared is written, the I’s are then taken out. Frequency increases, reactance increases (23:56-25:42). Graphs on frequency. Inductive reactance. Dotted line moves through a graph. Impedance (25:43-27:42). Circuit impedance. Graphs with straight lines and dotted lines, this is explained (27:43-29:01). Title: The effect of Impedance at Resonance. A sailor explains audio filtration using his voice, which is being recorded through a ribbon microphone. At resonance the impedance of the circuit is equal to the resistance value as Z = R. … At high frequencies the series circuit is inductive as: XL Greater Than XC , this gives the circuit a lagging power factor. The high value of current at resonance produces very high values of voltage across the inductor and capacitor. Inside a vacuum tube type radio transmitter (29:02-32:08). End credits (32:09-32:54).

This film is part of the Periscope Film LLC archive, one of the largest historic military, transportation, and aviation stock footage collections in the USA. Entirely film backed, this material is available for licensing in 24p HD, 2k and 4k. For more information visit http://www.PeriscopeFilm.com