9th October 2018

wikipedia

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What types of wires have a high resistance?

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Types. Nichrome, a non-magnetic 80/20 alloy of nickel and chromium, is the most common resistance wire for heating purposes because it has a high resistivity and resistance to oxidation at high temperatures. When used as a heating element, resistance wire is usually wound into coils.

Why does a thicker wire conduct more electricity?

The thin wire will conduct electricity, but there is more electrical resistance. The thicker wire is like the four lane highway. There's a lot less electrical resistance, and as a result, that light bulb burns brighter because more electricity can reach it.

Why are thick wires rather than thin wires used to carry large currents?

2) Why are thick wires rather than thin wires usually used to carry large currents? Ans. Thick wires have less resistance and so they will heat up less when a large current is passed through them. The resistance of a wire is proportional to its length and inversely proportional to its cross-sectional area.

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Do Superconductors have no resistance?

Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic flux fields occurring in certain materials, called superconductors, when cooled below a characteristic critical temperature. It was discovered by Dutch physicist Heike Kamerlingh Onnes on April 8, 1911, in Leiden.

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What is the resistance of a wire?

There is a resistance to the flow of an electric current through most conductors. The resistance in a wire increases as: The length of the wire increases. The thickness of the wire decreases.

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What do you mean by high resistance?

Resistance is the measure of opposition to electric current. A short circuit is an electric circuit offering little or no resistance to the flow of electrons. Short circuits are dangerous with high voltage power sources because the high currents encountered can cause large amounts of heat energy to be released.

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What is the relationship between resistance and heat?

Thus when temperature goes up, resistance goes up. For some materials, resistivity is a linear function of temperature. The resistivity of a conductor increases with temperature. In the case of copper, the relationship between resistivity and temperature is approximately linear over a wide range of temperatures.

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How does resistance change with temperature?

Surely, upon an increase in temperature, the atoms within the thermistor would vibrate with more energy and therefore more vigorously, hence making the electrons flowing through the electric circuit more likely to collide with one of the atoms, so increasing resistance.

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How is resistance affected by temperature?

Resistance increases, in case of conductor, with increase in temperature and decreases, in case of insulator, due to increase in temperature. So, with increase in temperature, the resistance of conductor increases. But in case of insulator, there is a large energy gap between the two bands.

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What Should the resistance be on a heating element?

Elements do have some resistance, so a reading of 10-16 ohms is normal, with higher ohm readings for 3,500 watt elements and lower readings for 5,500 watt elements. The wattage of your element is printed on the plastic block between the two screws where the wires were attached.

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How does temperature affect the current?

An electric current flows when electrons move through a conductor, such as a metal wire. This makes it more difficult for the current to flow, and causes resistance. As the temperature increases, the metal ions vibrate more. There are more collisions with the electrons and so the resistance increases.

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What is the formula for Ohm's law?

Ohm's law formula. The resistor's current I in amps (A) is equal to the resistor's voltage V in volts (V) divided by the resistance R in ohms (Ω): V is the voltage drop of the resistor, measured in Volts (V). In some cases Ohm's law uses the letter E to represent voltage.

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What is the resistance of Nichrome?

The unit of resistivity is then ohm-meters (Ωm). Nichrome, a non-magnetic alloy that is commonly made up of 80% nickel and 20% chromium, has a resistivity ranging from 1.10 × 10⁻⁶ Ωm to 1.50 × 10⁻⁶ Ωm (0.00000110 Ωm to 0.00000150 Ωm) and a very high boiling point (~1400 °C).

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Which wire is used in electric heater?

Nichrome: Most heating elements use nichrome 80/20 (80% nickel, 20% chromium) wire, ribbon, or strip. Nichrome 80/20 is an ideal material, because it has relatively high resistance and forms an adherent layer of chromium oxide when it is heated for the first time.

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What is Nichrome wire used for?

Nichrome Wire and Ribbon (80% Ni/20%Cr). Nichrome is a non-magnetic alloy of nickel and chromium. Nichrome is widely used in heating elements. It is wound in wire coils to a certain electrical resistance, and current passed through to produce heat.

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What kind of materials are used in resistors?

resistors are made from small rods of ceramic coated with metal such as a nickel alloy or a metal oxide such as tin oxide. The value of resistance is controlled by the thickness of the coating layer; the thicker the layer, the lower the value of resistance.

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How does the length of a resistor affect resistance?

Resistance increases with length because the electrons have further to go, so suffer greater collisions with atoms in the material. Look at these wires: Electrons moving through the short wire only feel resistance for a short time compared to the longer one. This means its resistance is less.

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Why do metal alloys have a high resistivity?

Free electrons are scattered off imperfections and alloys have many more of them than pure metals. The higher resistivity in alloys as compared to the constituents is caused by an additional scattering mechanism of the electrons called "alloy scattering". So there is a small relaxation time and hence large resistivity.

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Why do we use Nichrome in an electric heater?

Most heating elements use nichrome 80/20 (80% nickel, 20% chromium) wire, ribbon, or strip. Nichrome 80/20 is an ideal material, because it has relatively high resistance and forms an adherent layer of chromium oxide when it is heated for the first time.

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What type of wire is kanthal?

Kanthal wire is a ferritic iron, chromium-aluminium alloy and is used to build Rebuildable Atomizers (RBA's) and Rebuildable Dripping Atomizers (RDA's) for Mechanical Mods (Mech Mods). Kanthal Wire can be heated at temperatures up to 1400°C (2550°F). The actual type of wire size is identified by Gauge (AWG).

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