What is Solenoid?

A solenoid is a common term for a telephone coil used as an electromagnet. It also refers to any device that uses a solenoid to convert electrical energy into mechanical energy. The device generates a magnetic field from an electric field and uses the magnetic field to produce precise motion. Solenoid valves are often used to change power, such as in-car transmitters or valves, such as in the fuel system.

What is the working principle of Solenoid?

The solenoid is a corkscrew-shaped twine wired coil, usually made of steel. As with every electromagnet, a magnetic field is created when electricity passes through a wire. Electromagnets are more efficient than permanent magnets due to the fact they can be turned on and off by the use or removal of electrical energy, which makes them useful as switches and valves and lets them operate automatically.

The solenoid image, a type of electric magnet, whose purpose is to produce a magnetic field controlled by a coil wound into a solid helix.
CC0 1.0 Universal Public Domain Dedication | https://commons.wikimedia.org  | Svjo

As the electric current exceeds the solenoid coils, a magnetic field is created. The strength and size of the magnetic field are determined by the number of turns of coil of the solenoid. In a solenoid, the armature is movable: therefore, when the voltage exceeds the coil, the armature moves to increase the magnetic flux connection. It does this by closing the air gap between the two cores. The moving iron core or armature is loaded in the spring, so when the solenoid is de-energized, it will return to its original position.

The picture shows how Ampère's Law can be applied to the solenoid.
Movement of electric current
CC0 1.0 Universal Public Domain Dedication | https://commons.wikimedia.org  | Goodphy

Like all magnets, the solenoid magnetic field has advantages and disadvantages. It can attract or repel sensitive materials on the magnet. Inside the solenoid, the electromagnetic field causes the piston to move back and forth. This is how the solenoid coil moves linearly.

How does a solenoid valve work?

The solenoid valve is a simple function that can be used in various applications. The word solenoid is derived from the Greek word "Solen" meaning a channel or pipe. Solenoid valves are used in household and industrial machinery. There are a variety of designs to choose from, each with its own specific operating system. Although the applications have changed, their operating systems have remained the same.

The formation of a base valve, which controls the flow of water in this example. The upper half shows the valve in its closed position. The stream of energetic water enters A. B diaphragm stretchable and above it is a spring pushing them down.
Working of Solenoid valve
CC0 1.0 Universal Public Domain Dedication | https://commons.wikimedia.org  | Alfonso Gonzalez

What is a type of Solenoid?

There are different types of solenoids in the market, based on material.

AC solenoid

AC Laminated Solenoid consists of a metal core and a wire coil. The core is made of galvanized steel to reduce current losses, this helps to improve solenoid performance. AC solenoid has a special advantage because it can bring a large amount of energy to the first stroke. This is because they have inrush current flow (high-speed input current that draws electricity or electrical equipment when lit). They can use more strokes than DC laminated solenoids. They are available in a variety of configurations and widths and produce a clean, vibrant sound.

Line solenoid

Wire solenoids are very common among people. It consists of a wire coil wrapped around a movable metal backbone that enables us to use the force of gravity in the machine. This type of solenoid is widely used in early devices. This switching machine helps to complete the circuit and allows the current to flow smoothly.

DC C-Frame solenoid

Frame C refers to the structure of the solenoid. The DC C-Frame solenoid has only a C-shaped frame-mounted near the coil. Due to its highly controllable stroke performance, DC C-frame solenoid valves are used in many daily applications. Although it is called a DC solenoid configuration, it can be used in AC power systems. This type of solenoid is widely used in game consoles, cameras, scanners, circuit breakers, counters, and bill switches.

DC D-frame solenoid

This type of solenoid consists of a coil that connects two pieces. They have the same functions as C-frame solenoids, so D-frames can also be used for AC power and have a controlled pulse function. DC D solenoid valves are used in traditional and medical applications such as blood and gas analyzers, they are also used in gaming consoles, ATMs, etc.

Rotating solenoids

Rotating solenoids are actuators, much like linear solenoids. They make rotary actions with a sure torque over a defined rotation perspective. The bistable design is primarily based on the supply voltage reverse direction to exchange the rotation direction inside the polarized device.

Application of Solenoid

  • The primary use of solenoids is like a power exchange component. They are used in inductors, valves, antennas, and other types of components. Its use is in various areas such as medicine, industrial use, locking systems, automotive, etc.
  • They are used to control the valve electrically.
  • They can be used in a specific type of door lock system. These lock systems are very safe as they use electromagnets.
  • They are used in computer printers.
  • Solenoids are used in the fuel injection gear of cars.
  • The starter solenoid is an electromagnet that is activated to incorporate the internal combustion engine launcher. It is usually attached directly to the starter motor that controls it.

Advantages of Solenoid

The solenoid has many advantages over conventional coils:

  • By using the solenoid engine in cars, there is no air pollution.
  • The solenoid engine can work well with low torque.
  • Solenoids respond quickly when electricity is applied to them.
  • Solenoid engines can be used instead of fossil fuels.

Disadvantages of Solenoid

The solenoid has many disadvantages:

  • Chances are the coil needs to be replaced during its lifetime.
  • The need for a control signal to remain in place during its operation.
  • Sensitivity to voltage fluctuations or changes.
  • Unintentional closure of valve if the magnetic field is not properly set.

Common Mistakes

The most common and the frequent errors that the student will make while going through this topic are listed below:

  • The voltage applied to the coil must be correct.
  • There must not be any electric surge.
  • The coil must have appropriate number of turns as per requirement.

Context and Applications

In each of the expert exams for undergraduate and graduate publications, this topic is huge and is mainly used for:

  • Bachelor of technology in the electrical and electronic department
  • Bachelor of Science in physics
  • Master of Science in physics
  • Coil
  • Relay
  • Inductor

Practice Problems

Q1. Which type of coil is a solenoid?

(a) electrical

(b) mechanical

(c) chemical

(d) electromagnetic

Correct option: (d)

Explanation: The solenoid is an electromagnetic coil. When an electric current is supplied to the solenoid, a magnetic field is drawn into it and as a result the spool shifts to a selected location.

Q2. Iron is used in solenoids for __________.

(a) decreasing the magnetic field strength

(b) decreasing the electric field strength

(c) increasing the magnetic field strength

(d) increasing the electric field strength

Correct option: (c)

Explanation: Metal is used in solenoids to increase the magnetic field. This is due to the ferromagnetic properties of the metal. All ferromagnetic materials help to increase the magnetic field of an object.

Q3. The number of turns of the solenoid is inversely proportional to the magnetic field.

(a) True

(b) False

Correct option: (b)

Explanation: The stated statement is false as the rotation rate of the solenoid is directly proportional to the magnetic field. So as the rotation rate increases, the solenoid magnetic field will increase accordingly and at the surface, the magnetic field becomes weaker.

Q4. The number of turns of the solenoid is inversely proportional to the magnetic field.

(a) true

(b) false

Correct option: (a)

Explanation: The magnetic field produced inside the solenoid is stronger than the magnet outside it, and it is uniform. The presence of a strong magnetic field inside is due to the presence of current inside the solenoid.

Q5. What is the magnetic filed inside the solenoid?

(a) Zero

(b) Double of flux around the solenoid.

(c) Half of flux around the solenoid.

(d) No change

Correct option: (b)

Explanation: The magnetic filed inside the solenoid is zero.

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