These collisions change the momentum of the electrons. As a result, they lose some of their kinetic energy, because it is converted into the energy stored in the crystal lattice. This stored energy causes the conductor to warm up as the electric current runs through it.
It is important to note that the resistance of a given metal or an alloy depends on its geometry and does not depend on the direction of the external electric field that is applied to this material. As this external field intensifies, the electric current that runs through the metal increases, and more and more heat is emitted. This heat may increase so much that it will melt the metal. Fuses that have a wire component use this property. The wire melts if the heat exceeds the pre-set standards, as determined by the melting point of the material chosen for the wire.
The melted wire interrupts the current flow in the electric circuit. We can get an idea of what happens to fuses in action if we look at photographs or videos of filament failure in an incandescent light bulb. The most common use for electrical resistance is its use as a heating unit. We use this property while cooking and heating food on electrical stoves, baking bread and cakes in electrical ovens, and also when working with electric kettles, coffee makers, washing machines, and electric irons.
We rarely acknowledge this in our everyday life, but we owe our comfort to electrical resistance, whether we turn on the water heater for our shower, an electric fireplace, or an air conditioner with a heater function to heat our room. All of these devices have a heating element that uses electrical resistance.
Electrical resistance is used in the industry for drying when creating processed foods, to facilitate ideal temperatures for chemical reactions when making medicine, plastic bags, or for creating products from plastics using the process of extrusion. Unlike the case with metals, the crystalline structure of semiconductors is formed due to covalent bonds between atoms of the semiconductor. Because of this, semiconductors in their pure form without other materials mixed into them have a higher electrical resistance than do metals.
We should note that when talking about semiconductors we usually consider their intrinsic conductivity, not their resistance. When we mix the semiconductor material with another material that has atoms with a larger number of electrons on the outer electron shell, the semiconductor becomes n-type because of the extrinsic conductivity.
This is known as doping. In fact, semiconductors of this type along with the p-type ones are known as extrinsic semiconductors. Similarly, when we add other atoms to the semiconductor that have fewer electrons on the outer electron shell, we get a p-type semiconductor. In the most interesting case parts of the semiconductor have mixed conductance as a result of having two types of materials joined together.
The resistance of the p-n junction depends on the direction of this external electric field. Rectifier diodes, which are some of the key electronic components, operate on this principle. Unfortunately, when the electric current that runs through the p-n junction exceeds the allowed value, a thermal breakdown occurs.
This causes both the p-type and the n-type elements to move through the p-n junction, and the device fails. The electric field controls their source and drain resistance. The polarity created by the gate depends on whether it is the p-type or the n-type channel. MOSFET transistors are used almost exclusively in the on-off mode — they represent the majority of electric components in modern digital devices. Regardless of their performance, we can say that to a certain degree all transistors are in fact inertialess controlled electrical resistors.
The Physics of Resistance in Gases and Uses for It Under normal conditions, gases are great dielectrics because they have a very small number of charge carriers such as positively charged ions and electrons. This property of gases is used in contact switches, overhead power lines, and air-gap capacitors because air is a mix of gases and its electric resistance is very large. Gases have ionic conductance, and because of it when an external electric field is acting upon the gases, their resistance slowly decreases.
This is a result of the increase in the ionization of molecules. As the voltage increases, a glow discharge occurs and the resistance becomes more closely dependent on the voltage. This property of gases was used in the past in gas lights called stabistors for stabilizing the DC for a wide range of currents. As the external voltage further increases, the discharge in the gas becomes a corona discharge, the resistance drops more, and the discharge turns into an electric spark.
As this happens, an equivalent of a small lightning occurs and the resistance of the gas around the lightning drops to a minimum. The property of ionized gases to glow when a small electric current flows through them is widely used in neon lighting for advertising, for displaying the electromagnetic field neon voltage testers , and in sodium-vapor lamps used for lightning.
Energy-saving compact fluorescent lamps work on the same principle due to the ability of mercury vapors to glow in the ultraviolet spectrum. The light of the visible spectrum is produced by the conversion of the ultraviolet radiation into visible light in a phosphor coating, which covers the inside of the lamp. Similar to semiconductors, the resistance of gases is non-linear and depends on the external electric field.
Electrolytes are liquids that conduct electricity. Their resistance is determined by the concentration of ions of different polarities.
These ions are atoms or molecules that either lost or gained electrons. In the former case they are called cations, and in the latter case — anions. When we place two electrodes with opposite charge inside an electrolyte and thus create an external electric field, cations and anions start moving.
The mechanism of this process is based on the charging and the loss of charge of a given electrode. Anions give away extra electrons on the anode, and cations gain the missing electrons on the cathode. A significant difference between electrolytes and metals, semiconductors, and gases is the movement of particles of the electrolytes within them. It is widely used in medicine and technology, from refining metals by filtering out impurities to the introduction of medicine into a given area of the body through electrophoresis.
We owe our shiny bathtubs and faucets to electroplating — a process of covering surfaces with metals, chrome, and nickel in this case. The quality of electroplating depends on the temperature and resistance of the electrolyte, in which the process runs, as well as on other parameters. From the perspective of physics, our body is an electrolyte and we have to remember it when it comes to personal safety, in particular with regards to resistance and the electric current running through the body.
We should note that the lie detector works by measuring the resistance on different areas of the skin. It is believed to aid with determining which questions are uncomfortable for the interviewee when used in conjunction with other physiological measurements. The resistance of dielectrics is rather high, and this property is widely used in physics and engineering when using these materials as insulators.
The vacuum is the ideal dielectric. What resistance could we possibly talk about in a vacuum? Well, thanks to one of the less popular works of Albert Einstein compared to his famous work on relativity , the one that considers the work performed by electrons separating from a metal, using resistance in a vacuum, we can now create a number of electronic devices that have been serving mankind since the early days of electrical and RF engineering.
According to Einstein, any conducting material is surrounded by a cloud of electrons, which creates a cathode ray when an electric field is applied to them. Two-electrode vacuum devices have different resistance when the polarity of the applied voltage changes. Until the s, they were used for the rectification of alternating current.
Vacuum tubes with three or more electrodes were used to amplify signals. Now they are replaced by more energy-efficient transistors. What is the value of 2. Is kilo ohms bigger than megohms? How many ohms are there in 0. How do you convert ohms to Megaohms? How many ohms are in a Milliohm? What are the major reasons for resistance to change?
What are two factors that contribute to resistance to change? What are the ways to overcome resistance to change? What are barriers to change? What are the types of resistance to change? What is the resistance to change called? FAQ about converter. How to convert Megohm to Ohm?
Megohm is times Bigger than Ohm. Enter the value of Megohm and hit Convert to get value in Ohm. Check our Megohm to Ohm converter. Need a reverse calculation from Ohm to Megohm? You can check our Ohm to Megohm Converter. How many Ohm is 1 Megohm? How many Microhm is 1 Megohm? How many Volt per Ampere is 1 Megohm? How many Kilohm is 1 Megohm? Megohms to Ohms Converter Units of measurement use the International System of Units, better known as SI units, which provide a standard for measuring the physical properties of matter.
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