Why are copper metal wires used to conduct electricity?
Excellent answers, all. Really, on an engineering basis, aluminum and copper are the big competitors. Inside the house, copper is very much preferred. It is a better conductor and less subject to corrosion, oxidation and deterioration of properties when exposed to higher temperatures. It is about four times the cost of aluminum by weight, but for the limited amount of wiring inside of a house or small appliance, this is acceptable. For cross-country transmission of power, however, aluminum is much less dense than copper. Hence, even though one must use more volume of aluminum to get the same conductivity, the weight of the cables is much less. Also, the cost of stringing all of the over-land transmission systems with copper would be staggering. (Copper is up quite a bit these days... spot price has been well over $3/lb for a week or two. Aluminum usually runs $0.90 to $1.00 / lb.)For sheer conductivity, however, silver is the king! That is why the electronics industry loves it. Often the critical factor affecting function is not determined by the long range over which one is transmitting an electric signal, but rather by the speed and quality of the connecting points. Hence, a tiny dab of silver (or gold) at those points can be extremely effective. Silver actually has conductivity better than gold, but gold is totally resistant to oxidation. Something even silver and copper cannot claim.
Does electricity travel at the speed of light?
There is a simple answer and a complicated answer.Simple - no. The electrons in a wire that form the electric current move very slowly. The second hand on a watch moves faster than the electrons. The actual speed of electrons is about 1.2 inches per minute in a typical, home lighting circuit.Complicated - The effect, or electromagnetic wave, of electric current moves at nearly, but not quite, the speed of light.Think of a tube full of balls. If you push one more ball into the tube, the ball at the other end comes out immediately. This is why turning on a light switch has an immediate effect. The electrons in the wire all push on each other and thus the light goes on instantly.In theory, electricity moves at the speed of light and in practical application, this is true.However, in practice it is slightly slower because the electron from atom #1 has to cross the space to atom #2 in order to bump its electron over to atom #3 in the wire. This tiny delay adds up over very long distances and the speed of electricity over millions of miles turns out to be very close, but not quite the speed of light.
A cylindrical metal wire at room temperature carries electric current between its ends. One end at VA = 50 V, and the other end VB = 0V.?
Rank the following actions in terms of the change that each one separately would produce in the current from the greatest increase to the greatest decrease. In your ranking, note any cases of equality. (a) Make VA = 150 V with VB = 0 V. (b) Adjust VA to triple the power with which the wire converts electrically transmitted energy into internal energy. (c) Double the radius of the wire. (d) Double the length of the wire. (e) Double the Celsius temperature of the wire.
How do you calculate the percentage increase in resistance of a cylindrical wire that is stretched to increase its length by 10%?
Resistance of a cylindrical wire is:R=(rho) l/A =(rho)l^2/(Al)=(rho)l^2/V………(1)(rho) is resistivity of the material of the wire.l is length of the wire.A is area of normal cross section of the wireV is volume of the wire which remains constant on stretching the wire.New resistance after stretching,R'=[(rho)/V](1.1 l)^2=[(rho)/V](1.21)l^2=(1.21)R.Therefore,(R'-R)/R=(1.21 -1)=0.21OR[(R'-R)/R]x100=0.21x100=21%
What is the difference between single core and multicore cables?
Single core cable A single core wire is a cylindrical strand of metal. In single core wire there is only a single core of metal is present, mostly copper or aluminum.These wires are available in different thickness and gauges.Used for Domestic purpose Single core wires or cables are widely used Domestic purpose. They are mainly used in electrical appliances, these wires can take a good load that is why they are more preferred in domestic uses.Can handle high temperature Single core cables are very high ambient wires; these cables are a good conductor of electricity as well as heat. These cannot melt or burn easily.Multi core cables Multi core cables are cables, which contains more than one core in the cable. These are flexible cables which are widely used for electric purpose, these cables are professionally made with good quality.Used for industrial purpose Multi wires or cables are widely used for industrial purpose. These cables are the good conductor of electricity and can take loads and benefits in industrial sectors. It can take heavy load and can support heavy industrial machines.Use in Entertainment sector Multi core cables are widely used in the entertainment sectors like theaters, concert venues and many others. People use multi core cable and combine their power, AV and data to avoid any tangled cable.
If a wire is stretched to double its length, what happens to its resistivity?
The Resistivity of the wire will not change with the change in length. Resistivity is a property of the wire, it doesn't depend upon it’s length or cross-sectional area.However, If you are asking about Resistance, it will increase to 4 times it’s initial value.Resistance,R = ρl/AWhere,ρ=Resistivity of the wirel=lenght of wireA= cross section of the wireSo, now if you increase the length of wire by 2 times it’s cross-sectional area will decrease by 2 times, because the volume of the wire has to remain constant.Let, the initial and final radius of the wire be r1,&r2 respectively.Since the initial and final volume are equal, so2π(r1^2)l = 2π(r2^2)(2l)So, r2=r1/√2So, the cross-sectional area becomes 1/2 times the initial value.Putting the values in the formula for resistance, we get the new resistance 4 times greater than the initial vakuev of resistance.
The north pole of a bar magnet is brought near a coil of wire. What is the direction of the induced current: clockwise or counterclockwise?
R. Cruikshank has it right. A coil will always generate an EMF that attempts to keep the magnetic flux through the coil constant.