All Questions
39
questions
1
vote
2
answers
119
views
Why does the power loss in transmission cable increase when resistance is increased?
In transmission cables, why does power loss increase when length of conductor is increased? According to the formulas V=IR and P=I²R, When we increase the length, the resistance increases, while the ...
0
votes
1
answer
77
views
"Why do power lines use high voltage?" Loss in power equal to Current*Voltage? [duplicate]
I define P is the average power. So $P=IV$ and $I=\frac{P}{V}$.
$P_{loss}$ I define to be the power loss, which is equal to $I^2R$.
Substituting for $I$, $P_{loss} = \frac {P^2R}{V^2}$
So I get that ...
- 93
1
vote
1
answer
122
views
Transformers in Power transmission [duplicate]
Recently I learnt that transformers are used in the national grid to increase the voltage, so we get less current. But my understanding V=IR and by increasing the voltage we get more current, so what ...
- 69
1
vote
1
answer
225
views
High voltage in transmission line [closed]
I'm trying to understand why high voltage is used in transmission but I seem really confused by the explanations I read.
Here's what I could make out:
$$P_\text{loss} = \dfrac{ΔV^2}{R_t} = \dfrac{(...
- 349
21
votes
8
answers
13k
views
Why do we reduce only current to prevent power loss? Why not voltage?
In power transmission lines current is kept low and voltage is kept high to reduce the power loss. This is because $P = I^{2}R$ and $P = VI$. In order to reduce power loss we have to reduce $I$ since $...
- 335
1
vote
2
answers
39
views
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
378
views
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
0
votes
2
answers
306
views
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
0
votes
1
answer
254
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
0
votes
2
answers
84
views
Seemingly contradictory situation in electrical system loss
In a power supply system, we know that we decrease the current and increase the potential difference. If we decrease the current by a factor of 10 and increase potential difference by a factor of 10, ...
- 27
2
votes
2
answers
606
views
Ohm's law and Joules heating
Ohm's law state that the ratio of V and I gives us a constant value of R provided that the temperature is kept constant throughout. However, in accordance with the joule's heating it would get heated ...
- 29
1
vote
2
answers
292
views
When to use Ohm's law as opposed to using power formula?
I am a mechanic trying to gain a better understanding of electrical theory on vehicles. I have a sound understanding of Ohm's law and also the power formula (Power = Voltage x Current)
However, I am ...
- 15
0
votes
3
answers
739
views
Why does the power remain constant during the stepping up and stepping down of current in transformers?
I understand quite a bit of transformers, their structure and other concepts and formulas related to mutual induction. However I'm not able to explain why the electrical power has to be constant ...
user248823
8
votes
4
answers
2k
views
What's the point of an RMS value? [duplicate]
the RMS (root mean square) value of $f(x)$ is defined as:
$$f(x)_{rms}=\sqrt{\frac{\int^b_a (f(x))^2dx}{b-a}}$$
Why do we do this very specific thing of taking the square, the mean, and then the ...
- 167
0
votes
1
answer
163
views
If a light bulb is connected to different voltages, is there a single method to calculate the utilized power?
If a bulb is marked at 100W and 200V, we know that the bulb utilises a power of 100W when connected to a 200V potential difference. So, can we say that the bulb, when connected to twice the potential ...
