Overview:
“Electricity for Boys”, published in 1914, is a comprehensive guide to the early world of electricity. Author J.S. Zerbe, a Mechanical Engineer, guides young readers through hands-on experiments and explains the basic principles of electrical phenomena. The book encourages a hands-on approach, urging readers to build their own electrical devices and learn by doing.
Zerbe takes readers through the history of electricity, from the discovery of amber’s properties to the invention of the dynamo and beyond. He explains the different types of electricity (frictional, voltaic, and electro-magnetic), how to measure current, and explores the concepts of volts, amperes, ohms, and watts. The book also delves into practical applications of electricity, including telegraphy, telephony, electric bells, annunciators, burglar alarms, batteries, electrolysis, water purification, electric heating, and wireless telegraphy. Zerbe even touches on emerging technologies like X-rays and radium.
Key Findings:
- Electricity is a powerful force with numerous applications. The book highlights how electricity can be used to power machines, communicate, illuminate, heat, and even purify water.
- Electromagnetism is fundamental to many electrical devices. Zerbe stresses the importance of electromagnets in motors, dynamos, electric bells, and other inventions.
- Understanding the principles of electricity is crucial for innovation. By learning about the science behind electrical phenomena, readers are encouraged to explore and experiment with new ideas.
Learning:
- The nature of electricity and magnetism. The book explains how electricity and magnetism are intertwined and how they can be harnessed for various purposes.
- Key Details: The book describes the magnetic fields surrounding wires carrying electricity, the concept of magnetic lines of force, and how magnets attract and repel each other.
- The process of generating electricity. Readers learn about the three main methods of generating electricity: frictional, voltaic (chemical), and electro-magnetic.
- Key Details: The book explains the construction and operation of a simple dynamo, demonstrating how moving a conductor through a magnetic field creates an electrical current.
- Measuring electrical properties. Readers are introduced to units of measurement such as volts, amperes, ohms, and watts, and learn how these units relate to electrical force, quantity, and resistance.
- Key Details: The book explains the concept of resistance, the importance of standards for measurement, and various methods for detecting and measuring electrical currents.
- The applications of electricity in everyday life. Zerbe highlights the uses of electricity in telegraphy, telephony, electric bells, annunciators, burglar alarms, batteries, electrolysis, water purification, electric heating, and wireless telegraphy.
- Key Details: The book explains the principles behind these inventions and provides detailed instructions for building basic versions of these devices.
Historical Context:
- The early 1900s was a period of rapid innovation in the field of electricity. The book captures the excitement of a time when scientists were just beginning to understand the full potential of this powerful force.
- Key Details: The book highlights discoveries made by prominent scientists like Thales, Gilbert, Franklin, Galvani, Volta, Ørsted, Ampere, Faraday, and Ohm.
- Electricity was seen as a transformative force with great potential to improve lives. The book reflects the optimism of the era, suggesting that electricity could revolutionize everything from communication and transportation to medicine and industry.
- Key Details: The book describes the invention of the dynamo as a pivotal moment, enabling the creation of powerful electrical currents and leading to the development of a wide range of technologies.
Facts:
- Amber, a yellow resin, was the first substance known to exhibit electrical properties. When rubbed, it attracts and repels light objects. (This observation dates back to 600 BC).
- The torpedo fish is known for its ability to emit electric impulses. This was known even in ancient times.
- The Leyden Jar, invented in 1740, was the first attempt to store electricity. It used glass, tinfoil, and sulphuric acid to hold an electrical charge.
- Benjamin Franklin proved that lightning is a form of electricity in the 1750s. His famous kite experiment demonstrated this conclusively.
- Galvanic electricity, discovered in 1790, is produced by chemical reactions between metals and liquids. This discovery led to the invention of the first batteries.
- The voltaic pile, invented by Alessandro Volta in 1800, is a type of battery that uses alternating discs of zinc, copper, and moistened cardboard. It generates electricity through chemical reactions.
- Hans Christian Ørsted discovered the magnetic effect of electricity in 1820. This finding paved the way for the development of motors and dynamos.
- André-Marie Ampère proposed the idea of a motor and a dynamo powered by electromagnetism. This insight was critical to the development of electrical machinery.
- Ohm’s law defines the relationship between voltage, current, and resistance. It states that current is directly proportional to voltage and inversely proportional to resistance.
- The earth is a giant magnet. It has a north and a south magnetic pole, and magnetic lines of force flow between them.
- The needle of a compass aligns itself with the Earth’s magnetic field, pointing towards the north magnetic pole. This is why compasses are used for navigation.
- Iron and steel are the best materials for making magnets. Other metals, like sulfur, zinc, bismuth, antimony, gold, silver, and copper, are non-magnetic.
- Electromagnets are temporary magnets created by winding a wire coil around a core of iron. They are energized only when a current flows through the coil.
- A current flowing through a wire creates a magnetic field around it. This field extends beyond the surface of the wire.
- The action of a dynamo relies on the principle of electromagnetic induction. Moving a conductor through a magnetic field creates an electrical current.
- A Leyden Jar is a capacitor, a device that stores electrical energy. It stores charges on the tinfoil coating, separated by the glass dielectric.
- The intensity of an electric current is measured in amperes. One ampere is defined as the amount of current that deposits 0.001118 grains of silver per second in a standard solution of silver nitrate.
- The voltage of an electric current is a measure of its electrical potential. It is defined as the electrical pressure required to move one ampere of current through one ohm of resistance.
- Resistance is the opposition to the flow of electrical current. It is measured in ohms.
- Watts are a measure of electrical power. One watt is equal to one volt multiplied by one ampere.
Statistics:
- The first historical account of electricity dates back to 600 years B.C. Thales of Miletus was the first to describe the properties of amber.
- The art of electricity is less than fifty years old. (This statement is based on the book’s publication date in 1914).
- A standard solution of nitrate of silver is used to determine the ampere. A current of one ampere deposits 0.001118 grains of silver per second.
- The resistance of a column of pure mercury, 106.3 millimeters long and weighing 14.4521 grams, is equal to one ohm.
- One thousand watts make a kilowatt. This is the standard of measurement for dynamos and motors.
- A 16-candlepower, 105-volt lamp carries 0.5 amperes of current.
- An electric current surging back and forth on a wire can travel thousands of miles. (This refers to wireless telegraphy).
- A single tool, a magnet-winding reel, can wind over a thousand magnets.
- The speed of light is approximately 186,000 miles per second.
- The Earth’s magnetic poles are not exactly aligned with the geographical poles. They are slightly off, but close enough for practical purposes.
- The electro-motive force, or E. M. F., of each accumulator cell is about 2 volts.
- It takes 36 to 40 hours to initially charge an accumulator battery.
- The electrolyte in an accumulator cell is typically a mixture of pure sulphuric acid and water. The ideal ratio is about one part acid to four parts water.
- The temperature of the electrolyte during charging should not exceed 100 degrees Fahrenheit.
- A typical electric iron uses high-resistance wire wound around a slate spool.
- Aluminum conducts electricity about 50% better than silver.
- German silver, an alloy of copper, nickel, and zinc, has 12 to 15 times the resistance of silver.
- Aluminum costs approximately three times as much as copper.
- A 50-volt arc lamp requires a current of 100 volts.
- The temperature of an electric arc can reach up to 10,000 degrees Fahrenheit.
Terms:
- Electrolyte: A substance that conducts electricity through the movement of ions, often a liquid solution.
- Electrode: A conductor, such as a metal plate, through which an electric current enters or leaves a solution.
- Resistance: The opposition to the flow of electrical current in a conductor.
- Voltage: A measure of the electric potential difference between two points.
- Amperage: A measure of the rate of flow of electric current.
- Watts: A unit of electrical power, equal to one volt multiplied by one ampere.
- Induction: The phenomenon of inducing a current in a conductor by changing the magnetic field around it.
- Transformer: An electrical device that uses electromagnetic induction to change the voltage of an alternating current.
- Dynamo: A device that converts mechanical energy into electrical energy.
- Motor: A device that converts electrical energy into mechanical energy.
- Annunciator: A device that signals a call from a distant point, often used in alarm systems.
- Battery: A collection of two or more cells, each of which can produce electricity.
Examples:
- The “Crown of Cups” Battery: This early form of battery uses a series of cups filled with salt water and connected by metal strips with alternating copper and zinc plates. The current flows from zinc to copper within each cup and from copper to zinc externally.
- The Voltaic Pile: This early battery uses alternating discs of copper and zinc separated by moistened cardboard. The electric current flows from the zinc to the copper.
- The Leyden Jar: This device stores an electrical charge using a glass jar coated with tinfoil and filled with sulphuric acid.
- The Simple Current Detector: This device uses a coil of wire, a swinging magnet, and a pointer to indicate the presence and direction of an electric current.
- The Sulphuric Acid Voltameter: This device uses the electrolysis of acidulated water to measure the strength of an electric current by measuring the volume of gas produced.
- The Copper Voltameter: This device uses the electrolysis of copper sulphate to measure current by the amount of copper deposited on one electrode.
- The Electric Bell: This device uses an electromagnet to vibrate an armature, which strikes a bell.
- The Annunciator: This device uses an electromagnet to drop a numbered plate, indicating a call from a specific location.
- The Burglar Alarm: This system uses switches on doors and windows to trigger a bell or other alarm when the switches are activated.
- The Acoustic Telephone: This early telephone uses a string or wire to transmit vibrations from one cup to another.
Conclusion:
“Electricity for Boys” provides a fascinating glimpse into the early days of electrical technology. The book combines historical context, hands-on experiments, and detailed explanations of basic electrical principles, making it an engaging and informative read for young minds. Zerbe’s focus on building practical devices encourages readers to think creatively and explore the world of electricity. The book reveals how electricity was seen as a powerful force with endless possibilities, highlighting the excitement and rapid pace of innovation in the early 20th century.