What value should the resistance of a connected heating element have?


Question by: Pierfrancesco Bellini | Last updated: December 2, 2021

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A heating element has no “very high” or “very low” resistance. The total energy dissipated by the circuit is proportional to the current, so the resistance of the heating element must be low enough to draw enough current to generate enough heat.

When does the resistance of a conductor increase?

In fact, experimental measurements show that the resistance R of a wire is: directly proportional to the length l of the wire (if l increases, R increases); inversely proportional to the section A of the wire (if A increases, R decreases); dependent on the material with which the conductor is made.

What is the electrical resistance in a metal wire due to?

Basically the electrical resistance is temperature dependent. This is valid for all materials. … The electrical resistance of a typical conducting metal grows linearly with temperature, while the electrical resistance of a typical semiconductor decreases exponentially with temperature.

How is the I calculated in Electronics?

Use Ohm’s Law to calculate voltage.

I = V. / I * R = V.R /

How is the resistance of the electrical wires calculated?

The resistance of a conductor is directly proportional to the length and inversely proportional to the section. It follows that the mathematical formula for calculating the electrical resistance of a generic conductor is: R = ρ * l / s.

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How to find a resistance in a circuit?

If you know the voltage and current of the whole circuit, you can calculate the resistance using the equation: R = V / I. For example, consider a parallel circuit with a voltage equal to 9 volts and a current equal to 3 A. The total resistance is: R.T. = 9 volts / 3 A = 3 Ω.

How is the Joule effect calculated?

The electrical energy that is converted into heat by the Joule effect is given by the following formula: Q = P Δt = ΔV i Δt = R i2 · Δt. This law is also called Joule’s law.

How to calculate electronic R?

R = V / I: the resistance is given by the ratio between the voltage (V) ÷ current (I).

How do I calculate the voltage drop?

To have a confirmation of the result you can simply add the values ​​found of the potential differences on each resistor, which must be 12V (in our case) that is: V = V1 + V2 + V3 = 3.333v + 4.666v + 3.999v = 12v .

How to calculate the resistance to lower the voltage?

Ohm’s law

This law tells us that the voltage drop in Volts, in our case of a resistance, is equal to the product of the value in Ohm of the resistance by the current in Ampere that passes through it.

What is the electrical resistance due to?

Electric resistance is a scalar physical quantity that measures the tendency of a body to oppose the passage of an electric current when subjected to an electric voltage. This opposition depends on the material with which it is made, its size and its temperature.

What is the resistance of a conductor wire?

The electrical resistance R of a conductor is defined as the ratio between the potential difference ΔV applied to its ends and the current i that passes through it. … The resistance of a conductor is influenced not only by the material it is made of, but also by the geometric characteristics of the conductor wire.

How to make a DIY electric resistor?

How a resistor is made

Modern resistors are made of carbon, metal or metal oxide film. In these resistors, a thin film of conductive (though still resistive) material is helically wound and covered with an insulating material.

Why decreasing the section of a conductor increases its resistance?

In a conductor wire, the intensity of the current (I) is directly proportional to the voltage (V) and inversely proportional to the resistance (R). In simpler words we can say that, in a circuit: … the current decreases if the battery voltage decreases or the resistance of the circuit increases.

How does the electrical resistance of a conductor vary with temperature?

The resistivity and consequently the resistance of conductors, semiconductors and insulators depends on the temperature: The resistivity of a metal conductor is small and generally increases linearly with temperature. … Even in insulators the very strong resistivity decreases with increasing temperature.

When is a resistor shorted?

A short circuit indicates a connection with zero resistance between two points with different potential. … So it is absolutely not the case to experience the short circuit on the 220V at home, there is the risk of taking a discharge, as well as blowing up the system, or rather tripping the protection switch.

What resistance causes the voltage drop of a generator?

To estimate this voltage drop, due to constructive parameters of the generator, the internal resistance of the generator R is introducedthe. This is the generalized Ohm’s law.

What do Ohm’s two laws say?

Ohm’s law

The statement sounds exactly like this: “The intensity of current in a circuit is directly proportional to the voltage applied to it and inversely proportional to the resistance of the circuit itself”.

How to calculate R1 and R2?

Voltage divider formula

  1. R = V / I of which V is the voltage we want at the output, 5V in this case, and I is the current we want at the output 20mA, so 5 / 0.020 = 250 Ω
  2. 12V – 5V = 7 -> 7 / 0.020 = 350 Ω
  3. I = V / R -> 10V / 2000Ω = 5mA.
  4. R1 = 100 Ω R2 = 100 Ω

How do you find REQ?

  2. Circuit with resistors in series. View of two resistors connected in series.
  3. R1,2 = R1 + R2.
  4. If the resistances in series are more than two, the same rule applies for which the equivalent resistance will be:
  5. Req = R1 + R2 + R3 + ……. + Rn.

  6. Example. …
  8. Circuit with resistors in parallel.

How to calculate the value of the resistances in parallel?

Calculation of resistances in parallel

  1. Current in R1 -> I = V / R | I = 12V / 390 = 30mA.
  2. Current in R2 -> I = V / R | I = 12V / 2000 = 6mA.

In which household appliance is the Joule effect most observed?

This law, always in this reductive form, is the basis of the operation of many electrical devices including: the incandescent lamp, the magnetothermic switch, the fuse, the electric oven, the hairdryer, the electric water heater.

What is the Joule effect due to?

What is the Joule effect and what is it due to

When a user of an electrical circuit (or if you prefer a conductor) is crossed by current, it dissipates part of the electrical energy that is supplied to it in other forms of energy.

How to reduce the losses due to the Joule effect?

The only way to reduce copper losses is to decrease R, the resistance of the windings. I add another way of reasoning. The R of the windings is in series with the load, and the transformer voltage is applied to the series; most of it, we do 95%, goes to the load.

How does an ammeter fit into a circuit?

To connect them, you need to wear protective goggles. For the ammeter you need to disconnect the negative battery cable and get a 10 gauge or smaller electric wire. Then it is necessary to tighten the nuts at the base of the two ammeter connectors, crimp and solder the terminals to the cables.


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