Why are the resistance used in a resistance box is like?

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Why are the resistance used in a resistance box is like?

a rheostat and resistance box both act as sources of variable resistance in a circuit. In case of a resistance box, the resistance is in the discrete unit of 1 ohm while a rheostat varies the resistance in a continuous fashion along its length.

A resistance decade box or resistor substitution box is a unit containing resistors of many values, with one or more mechanical switches which allow any one of various discrete resistances offered by the box to be dialed in.

Q. What is a decade box used for?

Decade boxes are test instruments which use a series of resistors, capacitors, or inductors to simulate very specific electrical values. They can be quickly and easily substituted into a circuit and replace any standard value component.

Q. What is a resistance box?

Definition: The box which contains the resistors of different values for estimating and comparing the resistance is known as the resistance box. The accuracy of the resistance box is very high. … The main advantage of the resistance box is that the variable resistances are available at one point.

Q. What is the difference between rheostat and resistance box?

Answer Expert Verified now,you can understand the logic , why are the resistance used in a resistance box like 1, 2 , 2 , 5 , 10 , 20, 20, 50 , 100, 200, 200, 500,1000, 2000, 2000, 5000, ….. etc . we use these all values of resistance because we can easily got any integer or natural value of resistance .

Q. What is the principle of post office box?

It works on the principle of Wheatstone bridge to identify the resistance of wire connected and then by using wire resistivity and cross section calculating length of wire and thus determining where the cable had broken.

Q. What is a resistance?

Resistance is a measure of the opposition to current flow in an electrical circuit. Resistance is measured in ohms, symbolized by the Greek letter omega (Ω). … All materials resist current flow to some degree.

Q. Why wire is double folded in resistance box?

The wires in the resistance box are double folded and thus coiled to nullify the inductance effect. … Because of this magnetic induction caused by half of the wire, the magnetic induction induced by the other half of the wire is cancelled and the wires are preserved with pure resistance.

Q. What is unit of electric resistance?

The SI derived unit of electric resistance is the ohm, which is defined as a volt per ampere. … A statcoulomb is defined as ohms where c is the magnitude of the speed of light, and is energy-equivalent to the unit second per centimeter (). A preece is defined as ohms.

Q. What is electrical resistance called?

Resistance (also known as ohmic resistance or electrical resistance) is a measure of the opposition to current flow in an electrical circuit. Resistance is measured in ohms, symbolized by the Greek letter omega (Ω).

Q. What does 20K mean on a multimeter?

20,000 ohms

Q. How do you read a 20K ohm meter?

The ohm setting on the multimeter give you the maximum ohm it can measure up to. For example, 2k (0 to 2000 ohm), 20K (0 to 20,000 ohm), 200K (200,000 ohm), 2m (0 to . 002 ohm). If the resistance is greater than the range setting, it will give zero.

Q. What are the four things that affect the resistance of a wire?

There are 4 different factors which affect resistance:

  • The type of material of which the resistor is made.
  • The length of the resistor.
  • The thickness of the resistor.
  • The temperature of the conductor.

Q. What are the two factors that influence resistance?

There are several factors that affect the resistance of a conductor;

  • material, eg copper, has lower resistance than steel.
  • length – longer wires have greater resistance.
  • thickness – smaller diameter wires have greater resistance.
  • temperature – heating a wire increases its resistance.

Q. Does length of wire affect resistance?

The resistance of a long wire is greater than the resistance of a short wire because electrons collide with more ions as they pass through. The relationship between resistance and wire length is proportional .

Q. What is a specific resistance?

Specific resistance is defined as the resistance offered per unit length and unit cross-sectional area when a known amount of voltage is applied.

Q. What is the other name of specific resistance?

Specific resistance may refer to: Specific electrical resistance (also known as electric resistivity) Specific airway resistance (Raw/functional residual capacity (FRC)

Q. What is the symbol of specific resistance?

Specific Resistance (”ρ”) is a property of any conductive material, a figure used to determine the end-to-end resistance of a conductor given length and area in this formula: R = ρl/A.

Q. What is difference between resistance and specific resistance?

The resistance between two ends of a wire is the ratio of the potential difference of the two points to the current flowing through the conductor. Resistivity or specific resistance of a material is defined as the resistance of unit length and unit cross-section of that material.

Q. What are the 5 types of resistors?

This resistor includes two terminals which are mainly used for connecting through other kinds of components within the circuit. Types of fixed resistors are surface mount, thick film, thin film, wire wound, metal oxide resistor & metal film chip resistor.

Q. What is the formula of resistivity?

Resistivity, commonly symbolized by the Greek letter rho, ρ, is quantitatively equal to the resistance R of a specimen such as a wire, multiplied by its cross-sectional area A, and divided by its length l; ρ = RA/l. The unit of resistance is the ohm.

Q. Which conductor has highest resistivity?

Resistivity and Temperature Coefficient at 20 C

MaterialResistivity ρ (ohm m)Conductivity σ x 107 /Ωm

Q. What is the best conductor of electricity?

The most highly conductive metals are silver, copper, and gold. Copper, for example, is highly conductive and commonly used in metal wiring. Brass, on the other hand, contains copper but other materials in its makeup reduce conductivity. Pure silver is the most conductive of all metals.

Q. Which conductor has less resistivity?

The Resistivity of Various Materials A material with low resistivity means it has low resistance and thus the electrons flow smoothly through the material. For example, Copper and Aluminium have low resistivity. Good conductors have less resistivity. Insulators have a high resistivity.

Q. Which has higher resistivity Ge or Si?

Silicon is more suitable for high–power devices than germanium. One reason is that it can be used at much higher temperatures. … Pure germanium has a resistivity of 60 ohm–centimeters. Pure silicon has a considerably higher resistivity, in the order of 60,000 obm-centimeters.

Q. Why is Si preferred over GE?

The structure of Germanium crystals will be destroyed at higher temperature. However, Silicon crystals are not easily damaged by excess heat. Peak Inverse Voltage ratings of Silicon diodes are greater than Germanium diodes. Si is less expensive due to the greater abundance of element.

Q. What is the resistivity of germanium?

Table of resistivity for common materials

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Table of Electrical Resistivity for Common Materials
MaterialElectrical Resistivity at 20°C Ohm metres

Q. Why is Germanium a good conductor of electricity?

Pure silicon and germanium are poor conductors of electricity because their outer electrons are tied up in the covalent bonds of the diamondlike framework. … They are not conductors in the metallic sense of the word, but are semiconductors.