Introduction to resistor

overview

The resistor is a current limiting element. When a resistor is connected to a circuit, the resistance of the resistor will likely be determined by two pins, which may limit the present within the branch connected to it. A resistance that can not be modified is named a hard and fast resistor. The variable resistance is named a potentiometer or variable resistor. A super resistor is linear, that’s, the instantaneous current through the resistor is proportional to the instantaneous voltage applied. Variable resistor for voltage division. On the bare resistor body, one or two movable metal contacts are pressed tightly together. The contact position determines the resistance between each end of the resistor and the contact.

There’s a transparent functional relationship between terminal voltage and current. It’s a two-terminal device that reflects the flexibility to convert electricity into other forms. It’s represented by the letter R and the unit is ohm Ω. Real devices equivalent to light bulbs, heating cables, resistors, etc. will be expressed as resistor elements.

Resistance value a resistor The element is usually related to temperature, material, length and cross-sectional area. The physical quantity that measures the quantity of resistance as a result of temperature is the temperature coefficient, defined as the share of the resistance value that changes with a 1°C increase in temperature. The foremost physical feature of a resistor is the conversion of electricity into thermal energy. It will possibly even be said that it’s an energy-consuming element, and internal energy is generated when current flows through it. Resistors often play a task in splitting voltage and current in a circuit. Within the case of signals, each AC and DC signals can go through resistors.

Composition

A two-terminal electronic element manufactured from resistive materials with a selected structure and able to limiting the flow of current within the circuit. A resistance that can not be modified is named a hard and fast resistor. The variable resistance is named a potentiometer or variable resistor. A super resistor is linear, that’s, the instantaneous current through the resistor is proportional to the instantaneous voltage applied. Some special resistors, equivalent to thermistors, varistors and sensitive elements, have a non-linear relationship between voltage and current. Resistors are probably the most commonly used electronic circuit components, often in several series depending on power and resistance, for selection by circuit designers. Resistors are mainly used to control and stabilize current and voltage in circuits and will be used as shunts and voltage dividers, and may also be used as circuit matching loads. In keeping with the necessities of the circuit, it might probably even be used for negative or positive feedback of the amplification circuit, voltage to current conversion, voltage or current protection element when the input is overloaded, and will be formed into an RC circuit to oscillate, filter, bypass, differentiate , integration and time constant Components etc.

Principle of operation

The resistor consists of a resistor body, a skeleton and a terminal (the resistor body and the skeleton of the solid core resistor are combined into one), and it’s the resistor body that determines the resistance. Within the case of a resistor body with a uniform cross-section, the resistance value is

Within the formula, ρ is the resistivity of the resistive material (ohm·cm); L is the length of the resistor (cm); A is the cross-sectional area of ​​the resistor (square centimeter).

The thickness d of the skinny film resistor may be very small, it’s difficult to measure accurately, and ρ varies with the thickness, so it is taken into account as a continuing related to the skinny film material, which is named the film resistance. This is definitely the square film resistance value, so it’s also called square resistance (euro/square). For uniform foil

Where W is the width of the foil (cm). Normally, the R value needs to be inside a limited range, too large an R value will affect the operation stability of the resistor. Subsequently, the cylindrical resistor body uses the groove method, and the planar resistor body uses the circumferential pattern etching method to expand the resistance range and fine-tune the resistance value.

The volt-ampere characteristic is a graphical curve showing the connection between voltage and current at the top of a resistor. When the voltage and current are proportional (the characteristic is a straight line), it is named linear resistance, otherwise it is named nonlinear resistance.