LESSON ELEVEN. ELECTRIC WAVES.When a Leyden jar discharges under the conditions set forth in one of the previous lessons, portions of the energy of the current or discharge are thrown off from the conductor and do not return to it, but go traveling on in space.If a current is sent through a circuit, as the current increases, the magnetic field also increases, the magnetic lines enlarging and spreading outward from the conductor like the ripples on a pond. If the current is decreased, the magnetic lines all return back and close up upon the conductor, the energy all being re-absorbed into the circuit.If electrical oscillations of extreme rapidity such as those generated by a condenser discharge are substituted for a current slowly rising and falling, part of the energy radiates off into the ether aselectromagneticwaves and only a part returns back.The discharge of a Leyden jar or condenser only oscillates when the circuit contains a certain amount ofcapacityandinductancein proportion to the resistance of the circuit.Inductance is the property of a circuit by virtue of which lines of force are developed around it. Circuits containing a certain amount of inductance, capacity and resistance tend to oscillate electrically at a certain frequency.FIG. 26. Electric Waves.FIG. 26. Electric Waves.The electromagnetic waves thrown off by the aerial system follow the contour of the earth and so may cross mountains or travel anywhere. The waves emitted by the ordinary wireless station, making use of an aerial and a ground arehalfwaves terminating in the earth as shown in the illustration. In passing over the earth they are accompanied by ground currents which waste a certain amount of their energy in overcoming ohmic resistance and so reduce the intensity of the waves. For this reason propagation is always the best over water or moist earth whose resistance is low.A further peculiar weakening of the waves due to the absorbtion taking place in the air during sunlight. The difference between the signals in the day and their strength at night is very marked, being much stronger in the later case.
LESSON ELEVEN. ELECTRIC WAVES.When a Leyden jar discharges under the conditions set forth in one of the previous lessons, portions of the energy of the current or discharge are thrown off from the conductor and do not return to it, but go traveling on in space.If a current is sent through a circuit, as the current increases, the magnetic field also increases, the magnetic lines enlarging and spreading outward from the conductor like the ripples on a pond. If the current is decreased, the magnetic lines all return back and close up upon the conductor, the energy all being re-absorbed into the circuit.If electrical oscillations of extreme rapidity such as those generated by a condenser discharge are substituted for a current slowly rising and falling, part of the energy radiates off into the ether aselectromagneticwaves and only a part returns back.The discharge of a Leyden jar or condenser only oscillates when the circuit contains a certain amount ofcapacityandinductancein proportion to the resistance of the circuit.Inductance is the property of a circuit by virtue of which lines of force are developed around it. Circuits containing a certain amount of inductance, capacity and resistance tend to oscillate electrically at a certain frequency.FIG. 26. Electric Waves.FIG. 26. Electric Waves.The electromagnetic waves thrown off by the aerial system follow the contour of the earth and so may cross mountains or travel anywhere. The waves emitted by the ordinary wireless station, making use of an aerial and a ground arehalfwaves terminating in the earth as shown in the illustration. In passing over the earth they are accompanied by ground currents which waste a certain amount of their energy in overcoming ohmic resistance and so reduce the intensity of the waves. For this reason propagation is always the best over water or moist earth whose resistance is low.A further peculiar weakening of the waves due to the absorbtion taking place in the air during sunlight. The difference between the signals in the day and their strength at night is very marked, being much stronger in the later case.
LESSON ELEVEN. ELECTRIC WAVES.When a Leyden jar discharges under the conditions set forth in one of the previous lessons, portions of the energy of the current or discharge are thrown off from the conductor and do not return to it, but go traveling on in space.If a current is sent through a circuit, as the current increases, the magnetic field also increases, the magnetic lines enlarging and spreading outward from the conductor like the ripples on a pond. If the current is decreased, the magnetic lines all return back and close up upon the conductor, the energy all being re-absorbed into the circuit.If electrical oscillations of extreme rapidity such as those generated by a condenser discharge are substituted for a current slowly rising and falling, part of the energy radiates off into the ether aselectromagneticwaves and only a part returns back.The discharge of a Leyden jar or condenser only oscillates when the circuit contains a certain amount ofcapacityandinductancein proportion to the resistance of the circuit.Inductance is the property of a circuit by virtue of which lines of force are developed around it. Circuits containing a certain amount of inductance, capacity and resistance tend to oscillate electrically at a certain frequency.FIG. 26. Electric Waves.FIG. 26. Electric Waves.The electromagnetic waves thrown off by the aerial system follow the contour of the earth and so may cross mountains or travel anywhere. The waves emitted by the ordinary wireless station, making use of an aerial and a ground arehalfwaves terminating in the earth as shown in the illustration. In passing over the earth they are accompanied by ground currents which waste a certain amount of their energy in overcoming ohmic resistance and so reduce the intensity of the waves. For this reason propagation is always the best over water or moist earth whose resistance is low.A further peculiar weakening of the waves due to the absorbtion taking place in the air during sunlight. The difference between the signals in the day and their strength at night is very marked, being much stronger in the later case.
When a Leyden jar discharges under the conditions set forth in one of the previous lessons, portions of the energy of the current or discharge are thrown off from the conductor and do not return to it, but go traveling on in space.
If a current is sent through a circuit, as the current increases, the magnetic field also increases, the magnetic lines enlarging and spreading outward from the conductor like the ripples on a pond. If the current is decreased, the magnetic lines all return back and close up upon the conductor, the energy all being re-absorbed into the circuit.
If electrical oscillations of extreme rapidity such as those generated by a condenser discharge are substituted for a current slowly rising and falling, part of the energy radiates off into the ether aselectromagneticwaves and only a part returns back.
The discharge of a Leyden jar or condenser only oscillates when the circuit contains a certain amount ofcapacityandinductancein proportion to the resistance of the circuit.
Inductance is the property of a circuit by virtue of which lines of force are developed around it. Circuits containing a certain amount of inductance, capacity and resistance tend to oscillate electrically at a certain frequency.
FIG. 26. Electric Waves.FIG. 26. Electric Waves.
FIG. 26. Electric Waves.
The electromagnetic waves thrown off by the aerial system follow the contour of the earth and so may cross mountains or travel anywhere. The waves emitted by the ordinary wireless station, making use of an aerial and a ground arehalfwaves terminating in the earth as shown in the illustration. In passing over the earth they are accompanied by ground currents which waste a certain amount of their energy in overcoming ohmic resistance and so reduce the intensity of the waves. For this reason propagation is always the best over water or moist earth whose resistance is low.
A further peculiar weakening of the waves due to the absorbtion taking place in the air during sunlight. The difference between the signals in the day and their strength at night is very marked, being much stronger in the later case.