History and Observations of Electric Sparks
– Sparks were associated with electrical phenomena by Leibniz in 1671.
– Samuel Wall performed experiments with amber and cloth to produce sparks in 1708.
– Benjamin Franklin’s famous kite experiment extracted sparks from a cloud during a thunderstorm in 1752.
– Thomas-François Dalibard proved that lightning and electricity are the same by collecting lightning in a Leyden jar in 1752.
– Sparks have been studied and observed since ancient times.
Uses of Electric Sparks
– Electric sparks are used in spark plugs to ignite fuel and air mixtures in gasoline engines.
– Flame igniters use electric sparks to initiate combustion in furnaces and gas stoves.
– Spark-gap transmitters were widely used in wireless communication from 1887 to 1916.
– Electric sparks are used in metalworking techniques such as electrical discharge machining (EDM) and spark plasma sintering (SPS).
– Spark emission spectroscopy and laser-induced breakdown spectroscopy (LIBS) utilize electric sparks for chemical analysis.
Ignition Sources
– Electric sparks in spark plugs ignite fuel and air mixtures in gasoline engines.
– Flame igniters use electric sparks to initiate combustion in furnaces and gas stoves.
– Auto reignition is a safety feature in some flame igniters that senses the electrical conductivity of the flame.
– Electric sparks are used in various types of ignition systems.
– Ignition coils or magnetos provide the voltage for electric sparks in spark plugs.
Radio Communications and Spark-Gap Transmitters
– Spark-gap transmitters generate radio frequency electromagnetic radiation for wireless communication.
– Spark-gap transmitters were widely used in the early years of radio communication.
– Vacuum tube systems replaced spark-gap transmitters by 1940.
– Ships’ radio officers were nicknamed ‘sparks’ due to the use of spark-gap transmitters.
– Spark-gap transmitters played a significant role in the development of radio communication.
Electric Sparks in Metalworking
– Electric sparks are used in electrical discharge machining (EDM) to remove material from a workpiece.
– Electrical discharge machining is suitable for hard metals or those difficult to machine with traditional techniques.
– Spark plasma sintering (SPS) utilizes electric sparks to sinter conductive powders.
– SPS is faster than conventional hot isostatic pressing for certain applications.
– Electric sparks have revolutionized metalworking techniques. Source: https://en.wikipedia.org/wiki/Electric_spark
An electric spark is an abrupt electrical discharge that occurs when a sufficiently high electric field creates an ionized, electrically conductive channel through a normally-insulating medium, often air or other gases or gas mixtures. Michael Faraday described this phenomenon as "the beautiful flash of light attending the discharge of common electricity".
The rapid transition from a non-conducting to a conductive state produces a brief emission of light and a sharp crack or snapping sound. A spark is created when the applied electric field exceeds the dielectric breakdown strength of the intervening medium. For air, the breakdown strength is about 30 kV/cm at sea level. Experimentally, this figure tends to differ depending upon humidity, atmospheric pressure, shape of electrodes (needle and ground-plane, hemispherical etc.) and the corresponding spacing between them and even the type of waveform, whether sinusoidal or cosine-rectangular. At the beginning stages, free electrons in the gap (from cosmic rays or background radiation) are accelerated by the electrical field. As they collide with air molecules, they create additional ions and newly freed electrons which are also accelerated. At some point, thermal energy will provide a much greater source of ions. The exponentially-increasing electrons and ions rapidly cause regions of the air in the gap to become electrically conductive in a process called dielectric breakdown. Once the gap breaks down, current flow is limited by the available charge (for an electrostatic discharge) or by the impedance of the external power supply. If the power supply continues to supply current, the spark will evolve into a continuous discharge called an electric arc. An electric spark can also occur within insulating liquids or solids, but with different breakdown mechanisms from sparks in gases.
Sometimes, sparks can be dangerous. They can cause fires and burn skin.
Lightning is an example of an electric spark in nature, while electric sparks, large or small, occur in or near many man-made objects, both by design and sometimes by accident.