What is meant by specific resistance or resistivity?
Resistivity or specific resistance of a material is a measure of the resistance, which it offers to the flow of current through it. It is an intrinsic property of a material. Specific resistance depends on the composition, temperature, pressure of the material. This condition can be used to define resistivity.
What is the difference between resistance and resistor?
Resistance is the property of a conductor, which determines the quantity of current that passes through it when a potential difference is applied across it. A resistor is a electrical componet with a predetermined electrical resistance, like 1 ohm, 10 ohms 100 ohms 10000 ohms etc.
What is the formula 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. Specific resistance for materials are given in units of Ω-cmil/ft or Ω-meters (metric).
What is specific resistance and its unit?
Specific resistance is defined as “the resistance offered per unit length and unit cross-section area of that material when a known quantity of voltage applied at its end ”. The SI unit of specific resistance is Ohm-m.
What is specific resistance of wire?
The specific resistance or resistivity of a wire is the property of the material of it. It does not depend on mass, length or cross-section of wire. It may change with temperature.
What does specific resistance depend on?
The specific resistance of a wire depends on the temperature and on the material that is used in the wire.
What is the specific resistance of copper wire?
0.0171 Ohm
What is the symbol for direct current on a multimeter?
Different multimeters have different symbols for measuring direct current (and the corresponding voltage), usually “DCA” and “DCV,” or “A” and “V” with a straight bar above or next to them.
Does TV use AC or DC?
Batteries and electronic devices like TVs, computers and DVD players use DC electricity – once an AC current enters a device, it’s converted to DC. A typical battery supplies around 1.5 volts of DC.
Are 12 volt batteries AC or DC?
There are both DC (direct current as from 12 volt batteries) and AC (alternating current like what you use in your house) systems and issues on many boats, although some boats, particularly smaller ones, only use DC.
Are homes AC or DC?
Home and office outlets are almost always AC. This is because generating and transporting AC across long distances is relatively easy. At high voltages (over 110kV), less energy is lost in electrical power transmission.
Why AC is used in homes not DC?
Simply put, AC voltage is capable of converting voltage levels with just a transformer, making it far easier to transport across great distance than DC, whose conversion requires more complex electronic circuitry. Electric charge in AC periodically changes direction, causing the voltage level to reverse.
Which is better AC or DC?
DC power is significantly more energy efficient than AC power. DC motors and appliances have higher efficiency and power to size characteristics. DC-based lighting (LED) is as much as 75% more efficient than incandescent lighting.
Why AC is dangerous than DC?
Alternating current (A.C) is five times more dangerous than Direct current (D.C). The frequency of the alternating current is the main reason for this severe effect on the human body. The frequency of 60 cycles is in an extremely harmful range. At this frequency, even a small voltage of 25 volts can kill a person.
Does a fridge use AC or DC?
Unfortunately, you can’t plug an AC refrigerator straight into a DC power source. You need a power inverter between the source and the refrigerator. So the power converts from DC to AC through the inverter, goes into the refrigerator and converts to DC again. During each stage of the conversion, some power is lost.
Can AC appliances run on DC?
Short answer: No, most AC devices could not run off DC. If your input circuit is a diode rectifier followed by capacitors, after which everything in the system is expecting DC, then you should be able to feed DC into the circuit.
Where is DC current used?
DC is commonly found in many extra-low voltage applications and some low-voltage applications, especially where these are powered by batteries or solar power systems (since both can produce only DC). Most electronic circuits require a DC power supply.
What devices use AC and DC?
Uses. Direct current is used in any electronic device with a battery for a power source. It is also used to charge batteries, so rechargeable devices like laptops and cell phones come with an AC adapter that converts alternating current to direct current.