All Questions
172
questions
1
vote
2
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39
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Resistance And Electric Power
In a practice problem A motor rated at 20 A with a voltage of 115V exerts a force of 4900 N over a distance of 10 m in 30 s. Using the formulas $P=VI$ and $P=\frac{Fs}{t}$, we can see that the motor ...
- 297
0
votes
1
answer
384
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Why is the brightness of a light bulb dependant on power?
If:
Temperature is a measure of the average (kinetic) energy of the particles which make up some material
Power is measure of energy transferred per second (J/s)
The temperature of the filament in a ...
- 33
2
votes
2
answers
3k
views
Why is high voltage more deadly than low voltage?
Why is higher voltage said to be more dangerous? Doesn't higher voltage decrease current as P = IV where P is constant, thus making it less deadly?
- 323
1
vote
2
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147
views
On a nanoscopic level, what really happens to the electrons in the secondary coil of a step-up transformer?
I know that when AC is passed through the primary coil of a step-up transformer a higher emf is induced in the secondary coil (with more turns) of the transformer. Since energy is conserved, and P = ...
- 337
2
votes
2
answers
169
views
Confusion over Van de Graaff vs. Electric Fence
It is said "It is not the volts that kill you, but rather the current".
However, volts is directly related to current as V= IR (current x resistance).
Since the resistance of one particular ...
- 45
0
votes
0
answers
53
views
Does a bulb offer still offer resistance even after it gets fused? [duplicate]
Sorry, for my naivety this is my first time posting here.
But, my question is that will the bulb offer any resistance after it's fused?
I know that no current can flow though the fused bulb i.e. $I=0$....
- 101
2
votes
1
answer
519
views
Will I get shocked if I touch only the live wire while standing bare feet on the dry floor of my appartment?
In contrary to static electricity the mains electricity must return to the power plant. When I touch the live then the current flows through my body and the floor of my appartment and through soil to ...
- 170
13
votes
7
answers
6k
views
Why it is more dangerous to touch a high voltage line wire where current is actually less than households?
I have seen that power is transmitted from power stations to households at high voltage and low current to minimize the power loss.
That means the current in the transmission line is less than the ...
- 356
-1
votes
1
answer
181
views
Electric arc and electric spark differences? [duplicate]
Why does an electric spark occur discontinuously while an electric arc is not extinguished as long as the current is maintained?
- 59
3
votes
1
answer
5k
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What is the difference between electric spark and electric arc?
In my student book they separate these two and indicate that sparks need high voltage to occur while arcs need low voltage with normal or low pressure and electric arcs CAN come with heat and bright ...
- 59
0
votes
2
answers
306
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Why current drops when voltage increases?
https://www.youtube.com/watch?v=ubZuSZYVBng&t=329s
In the video above the man put a 200 thousands volt ball near a non-charged one and a very tiny current appear between them. But I think with ...
- 59
7
votes
4
answers
48k
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Why don't we get a shock touching neutral wire?
Neutral wire has a V same as ground i.e almost 0. Also it carries some current. So if we touch the wire don't we to become a part of the circuit? Even if we are on the ground and current should flow ...
- 103
0
votes
2
answers
784
views
How does current flow through the earth and back to the supply to break the fuse?
From my textbook, it says when the live wire touches the metal casing, a current will flow to the earth and blow the fuse located in the live wire. But through what devices will the current flow after ...
- 113
0
votes
1
answer
255
views
Power and power loss during transmission of power
So let's say power to be delivered to homes is 80 kW($P_3$ = 80 kW) and the houses have to receive it at 220 V ($V_3$ = 220 V). The substation is a 4000 V to 220 V step-down transformer and $R_2=15\ \...
- 15
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1
answer
698
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What does the labelling of a conductor such as: 24 W 12 V mean? Does this mean the resistance of the wire or the current?
So I came across a question where a lamp was labelled 24 W and 12 V. 2 lamps that were identical and had this labelling were then put in series with a voltage supply of 12 V.
Obviously the individual ...
- 220