Voltage resonance and current resonance (1976)

An example of the simplest oscillatory system.

The experiment demonstrates forced mechanical oscillations.

Two tuning forks.

By making one tuning fork sound, we obtain the sound of the second without mechanical action.

This is also an example of an oscillatory system.

The oscillation frequencies of the tuning forks are equal.

The concept of resonance.

Electrical circuits of radio devices.

Examples of serial and parallel oscillatory circuits of radio engineering devices in which resonance occurs.

An electrical circuit in which voltage resonance occurs.

An electrical circuit in which current resonance occurs.

A circuit diagram of an oscillatory circuit.

Phenomena occurring in the circuit when the generator is turned on.

Subsequently, the current of the circuit's natural oscillations decreases, and the amplitude of the resulting current increases.

Then the current amplitude, having reached its maximum, will depend only on the circuit parameters.

Preliminary conditions of the experiment.

Conditional display of the process parameters.

Resonance in a serial circuit.

Circuit image.

Maximum current in the circuit.

The concept of the resonant frequency of a circuit.

Image of the processes occurring in the circuit when the frequency changes.

Graph of the resonance curve of the circuit.

The concept of voltage resonance.

An experiment confirming this concept.

A formula for calculating the quality factor of a circuit.

The resonance condition in a circuit can be achieved not only by changing the frequency, but also by changing the parameters of the circuit itself.

Electrical circuit of a transistor radio receiver.

In the circuit of this receiver, resonance is achieved by changing the capacitance of the capacitor.

In a powerful transmitter cascade, the circuit is tuned by changing the inductance of the coil.

A working TV screen.

As a rule, in receivers, transmitters, and TVs, resonance tuning is achieved by simultaneously changing the inductance and capacitance.

Radio receiver panel.

Resonance in a parallel circuit.

Schematic diagram of a parallel circuit.

When the source frequency changes, the current in the common circuit changes and the currents in the circuit branches change.

At resonance, the current is 0. The current in the branches has the same value, which means that the reactances of the circuit branches are equal.

When the frequency decreases relative to the resonant frequency, the current in the inductive branch increases and vice versa.

When the generator frequency decreases, the current in the capacitive branch of the circuit drops.

With increasing frequency, the current increases.

The relationship between the currents in the common circuit and the circuit branches.

In an ideal circuit, at the moment of resonance, the current flows only in its internal circuit.

Here, electrical energy is converted into magnetic energy and vice versa.

Schematic diagram of a real circuit.

At resonance, the current in the common circuit is not 0, since losses in the circuit are compensated for.

Graph of the equivalent resistance versus the source frequency and graph of the current versus this frequency.

Formula for the quality factor of a parallel circuit.

Graph of the dependence of the current of the common circuit on the resistance of the circuit itself, which changes according to the law of the resonance curve.

The voltage on the circuit depends slightly on the frequency.

The case when the resistance of the source is high.

In this case, the current mainly depends on the internal resistance of the source.

Changing the resonant resistance of the circuit has almost no effect on it, but the voltage on the circuit changes sharply, according to the law of the resonance curve.

Oscilloscope screen.

Radio broadcasting towers.

Traffic police station on the city square.

Examples of using radio communication.

Ambulance.

Antennas at the airport.

Airplane landing.

Astronaut, broadcasting an image from space.

Space communication station.

Radio telescope.