What are the three states of the circuit?

The working state and characteristics of the circuit: 1. Open circuit: also called open circuit, because there is no conductor connection in a certain part of the circuit, the current cannot pass, resulting in the disappearance of the current in the circuit, and there is generally no damage to the circuit.

2. Short circuit: The power supply is directly connected to a closed circuit by the wire without any load, which is easy to cause circuit damage, instantaneous damage to the power supply, such as high temperature and burning out the wire and power supply. 3. Pathways:

Circuits that connect everywhere. Circuit Introduction: The circuit through which the current flows is called a circuit.

In its simplest form, a circuit consists of components such as a power supply, a load, wires, and auxiliary equipment, which are connected in a certain way to provide a path for the flow of charge. The basic laws followed by circuits: 1. Kirchhoff's law of current:

The sum of currents flowing into a node is equal to the sum of currents flowing out of nodes. 2. Kirchhoff's voltage law: the sum of loop voltages is zero.

3. Ohm's law: The voltage at both ends of a linear element (such as a resistor) is equal to the product of the resistance of the element and the current flowing through the element. 4. Norton's theorem:

Any two-terminal network consisting of a voltage source and a resistor can always be equivalent to a parallel network of an ideal current source and a resistor. 5. Thevenin's theorem: any two-terminal network composed of a voltage source and a resistor can always be equivalent to a series network of an ideal voltage source and a resistor.

There are three states of circuits: 1. The circuit is connected everywhere to form a loop. Second, the circuit is disconnected somewhere and cannot form a loop, which is called an open circuit or open circuit.

3. The two ends of a certain part of the circuit that originally have voltage are turned on unexpectedly, which is called a short circuit. Short circuits can damage power supply units and components, and are in a dangerous state and must be avoided.

The specifics of the three working states:

1. Pathway status:

A path is the switch in a circuit through which current flows through the load. In this state, the relationship between the power supply terminal voltage and the load current can be determined by the characteristics outside the power supply, and according to the size of the load, it can be divided into three cases: full load, light load and overload. The working state of the load at the rated power is called the rated working state or full load; The working state below the rated power is called light load; The working state higher than the rated power is called overload.

Because overload is very tolerant of burning out electrical appliances, overload is generally not allowed.

2. Short-circuit state.

If the external circuit is turned on by a conductor with a resistance value of approximately zero, the power supply is in a short-circuit state, in which the current in the circuit (short-circuit current) i e r. We know that the internal resistance of the power supply is generally very small, so the short-circuit current may reach a very large value, which will have the risk of the power supply burning, and must be strictly prevented to avoid it.

3. Open circuit state.

An open circuit is when the open circuit at both ends of the power supply is disconnected somewhere, no current passes through the circuit, and the power supply does not transmit electrical energy to the load. For power supplies, this state is called no-load. The main feature of the open circuit state is that the current in the circuit is zero. The voltage and electromotive force at the power supply end are equal.

1.For example, in a simple DC circuit, RT is the load resistance and BQ is the internal resistance of the power supply.

If the switch S is closed, the power supply supplies current and power to the load, and the circuit is in the load state. If the switch is turned on, the circuit is not connected, and the circuit is in a no-load or open-circuit state. If the two transmission lines are shorted after the switch is closed, the circuit is in a short circuit.

2.There is a limit to the voltage and current of any actual power supply, and this limit is called the voltage rating (rated voltage un) and current rating (rated current in) of the power supply.

3.Under the action of the rated voltage, the load current is less than the rated value, which is called underload or light load.

4.A load current greater than the rated current is called an overload.

5.The load current is equal to the rated value and is referred to as full load.

6.Open circuit state (or no-load state): The current in the circuit is zero, and the power supply from the power supply to the load is also zero.

The terminal voltage U0 of the power supply when the circuit is open is called the open circuit voltage, also known as the no-load voltage. UO is equal to the electromotive force of the power supply (i.e., the voltage of the voltage source).

7.The power supply is directly shorted by the conductor without load resistance to form a path, which is called a short circuit.

8.At this time, there is only a small internal resistance in the current path, so the current is very large. This current is called the short-circuit current ISC.

9.A short circuit is a serious accident. It can be caused by damage to insulation, careless wiring, and incorrect operation, among other reasons.

When a short-circuit accident occurs, the heat generated by a large short-circuit current will damage the power supply or the electrical instruments and other devices in the circuit through which the short-circuit current flows. In order to prevent serious consequences caused by short circuits. Protective devices such as fuses (commonly known as fuses) or automatic circuit breakers are usually connected to the circuit, and in the event of a short circuit, the faulty circuit can be quickly and automatically removed.

The three states of a circuit are path, open, and short. The path is the complete circuit, and the electrical appliances are operating normally. An open circuit is caused by the switch not closing, or the wire is disconnected. A short circuit is when both ends of the appliance are directly connected to the power supply, resulting in excessive local current.

The three states of a circuit are: path, open, and short.

The details are as follows: 1. Pathway:

The 1 in the figure above is the pathway state. The characteristics of the circuit in the path state are: the circuit is unblocked, the current flows through the load normally, and the load is in a normal working state.

2. Open circuit: 2 in the above figure is the open circuit state. The characteristics of the circuit in the open state are: the circuit is disconnected, the circuit cannot flow through the load, and the load does not enter the working state.

3. Short circuit: 3 in the above figure is the state of short circuit. The characteristics of the circuit in the short-circuit state are:

Current can pass through the circuit, but the current is very large, the current does not pass through the load, and the load does not work. Due to the high current, it is easy to cause burnout of the power supply and wires. It is a state of failure that is prone to accidents.

The various devices that use electrical energy in a circuit are collectively referred to as loads. The function of the load is to convert electrical energy into other forms of energy. For example, an electric furnace converts electrical energy into heat; Electric motors convert electrical energy into mechanical energy, and so on.

Lighting fixtures, household appliances, machine tools, etc., which are commonly used, can be called loads. Connecting wires are used to connect power supplies, loads, and other auxiliary equipment into a closed loop, which plays the role of transmitting electrical energy.

Parallel circuit is one of the two basic ways to make the current between the circuit elements in parallel have more than one independent path of each other, which is one of the two basic ways to form a circuit. For example, a simple circuit containing two light bulbs and a 9 V battery. If two bulbs are connected to the battery separately by two sets of wires, the two bulbs are connected in parallel.

There are three operating states of circuits: path, open or open, and short.

Based on the circuit of three working states.

Access; Opening; Short circuit 1 The path state should make the electrical equipment work normally, the electrical equipment should be made to work at the rated voltage, and when the current passing through the electrical appliance reaches the rated current, this working state is called the rated working state. When the electrical equipment works in the rated state, it is the most economical, reasonable, safe and reliable, which can ensure that the electrical equipment has a certain service life. If the bulb marked with 220V and 100W cannot be connected to the 380V power supply when in use, it should be made to work in the rated state as much as possible, otherwise it may be burned out.

As shown in Figure 1-8, after the switch S is closed, if the voltage at both ends of the load RL is the rated voltage and the current flowing is the rated current, the circuit is in the rated working state. Because mains voltages fluctuate frequently, the voltage, current, and power of electrical equipment are not necessarily equal to their ratings when they are actually used.

2.Open-circuit or open-circuit stateThe so-called open-circuit means that the power supply and load do not form a closed loop. As shown in Figure 1-8, when the switch S is disconnected, the circuit is in an open circuit or open circuit state, and the external circuit resistance can be regarded as infinity

The current in the circuit is zero, i.e., i.e., i.e., i.e., i.e., u=e, and in automotive contactors, the open circuit is caused by poor contact due to insufficient filler.

3.Short-circuit status.

A short circuit is a closed circuit in which a power supply is directly connected through a wire without a load, as shown in Figure 1-8. At this time, the circuit is in a short-circuit state, and the voltage at the load terminal is zero, i.e., u=0. The internal current is maximum, i.e., is=e r0.

Because the internal resistance R0 of the power supply is very small, the IS is very large, which greatly exceeds the rated value, causing damage to the power supply and line, and even causing fire accidents. The main causes of short circuits are: damaged insulation or improper wiring.

In order to prevent damage to electrical equipment caused by short circuits, fuses and automatic circuit breakers can be connected at the output end of the power supply, and the power supply can be quickly cut off in the event of a short circuit fault to avoid major accidents. The picture shows the short circuit phenomenon of automobile contactor.

Figure 1-10 Short circuit in an automotive contactorIn a nutshell, there is a voltage when there is a current in the resistive element. But there are two special cases: zero resistance and infinite resistance.

When r=0, it is called zero resistance. At this time, the circuit is short-circuited, and the voltage is zero, which also means that the switch is closed and the current is maximum, i.e., is=e r0. When r = is called infinite resistance, the circuit is open, the voltage is the supply voltage, and the current is 0.

Find the voltage of U2 in the three working states of the circuit [Example 1-1]. Fig.

Figure 1-11 Solution for Scenario 1-1: i3 = 0i2 = 0i1= =1u2=-e2 + i1r1 + e1 = 6 @2019

There are three states of the circuit, namely: path, open circuit, and short circuit.

Path - a normally switched on circuit, with a continuous current in the circuit, that is, a circuit in which the electrical appliance can work.

Open circuit - a circuit where there is a cut off somewhere in the circuit and there is no current in the circuit circuit, that is, a circuit in which the electrical appliance does not work.

Short Circuit - Directly connect the positive and negative poles of the power supply with wires, this situation is called short circuit. If the power supply is short-circuited, there will be a large current in the circuit, which may burn out the power supply, which is not allowed.

Special emphasis added:

When the power supply is short-circuited, there will be a large current in the power supply, which will burn out the wires and the power supply. When an electrical appliance is shorted, for example, when the bulb is shorted, the bulb is not burned out, but no current flows through the bulb, and the current flows through the wire that shorts it, so the bulb does not emit light.

There are three states of circuits: 1. The circuit is connected everywhere to form a loop. Second, the circuit is disconnected somewhere and cannot form a loop, which is called an open circuit or open circuit. 3. The two ends of a certain part of the circuit that originally have voltage are turned on unexpectedly, which is called a short circuit.

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