All Questions
135
questions
0
votes
1
answer
105
views
Understand power rating in layman terms
I have recently started the chapter of electricity of class 8. I am not understanding the concept of power rating of appliances. When we say that a bulb is rated 220V-100W, which means, according to ...
0
votes
6
answers
136
views
What is electromotive force? What's its relationship to Voltage? + clarification of confusion
So first of all, yeah I know that the electromotive force is not a force (the name was coined by Alessandro Volta I think).
About Power and dissipated power
The power with wich a battery provides the ...
- 11
0
votes
2
answers
42
views
How is power dissipated proportion to current and current squared?
$P=IV$ and $P=I^2R$. Does this mean that $P$ is proportional to both $I$ and $I^2$? I don't understand this concept. And when should I use the various formulas for power? When another variable is ...
0
votes
1
answer
75
views
Electricity: Ohm law vs Power in the Water analogy
I'm trying to understand electricity principles with the water analogy. I know this analogy is not perfect, but so far it has helped me the most.
To recap:
voltage (volt) is like water pressure
...
- 107
3
votes
1
answer
266
views
Is power of a battery constant?
In my question I'm neglecting the impact of discharging.
I'm trying to make sense of Watt's law: $$P=IV.$$ I always thought that the voltage and the power of a battery were constant features that ...
-1
votes
2
answers
141
views
Energy lost in a resistor and its temperature
The power lost across a resistor is proportional to the square of the voltage drop across it. This means by increasing the voltage across the resistor, the energy lost in it in a given time grows non-...
0
votes
1
answer
58
views
Power delivered to a Resistor is $V^2/R$. Does size of battery matter?
I had connected a thin Resistor wire to series combination of six coin cells or to a small sized 9V battery. The wire got hot in a normal way BUT when I connected the same resistance wire to a large ...
- 1,357
0
votes
3
answers
169
views
Why is Power in an electric circuit equal to $VI$? [closed]
Where did this formula come from? Everyone I asked just told me to substitute values of in ohms law to derive this but no one told why is power equal to voltage * current. Part of the reason for this ...
- 9
0
votes
0
answers
41
views
Does $P=VI$ contradict $V=IR$? [duplicate]
Imagine there's a dam generating power (P) that needs to be transported 100km away. Engineer Pedro suggests increasing the voltage to reduce current acording to P=VI, while Engineer Juan suggests ...
-1
votes
2
answers
147
views
How high voltage and low current is beneficial for power transmission which is contradicting $V²/R$? [duplicate]
I have read that during power transmission high voltage is used because for same power output, high voltage produce low current and due to low current, according to I²R, heat loss through cables are ...
- 204
2
votes
1
answer
98
views
Power of an electrical equipment
Let's say I have equipment of resistance $R$ (maybe a bulb or heater). If I apply a voltage $V$ to it, the power used by the equipment will be $V^2/R$ assuming Ohm's law holds for the equipment.
If I ...
- 349
0
votes
2
answers
213
views
Why does Ohm's law not work in a simple lightbulb circuit? [closed]
I was studying the module "Physical foundations of Computer Science" and was asked to construct a circuit with 3 lightbulbs which operate at $110V$ and can develop powers of $55W$, $55W$ and ...
0
votes
1
answer
36
views
Electrical power in series and parallel [closed]
I have confused myself massively and would like some help.
In my situation we have a cell with emf $V$ and no internal resistance, we hook up 2 lamps of resistance $R$ ohms in series, I have ...
- 195
4
votes
5
answers
2k
views
Can you charge a capacitor with only voltage (without current)? If No, then how does a capacitor correct power factor?
Let me explain you why I am asking this question.
The other day I was studying about power factor correction of a (step up or any) transformer. It said that on the output side of transformer's ...
- 129
1
vote
3
answers
501
views
Power dissipated in a circuit
If total power dissipated in a DC circuit is given by $P = VI$ and power dissipated as heat is given by $P=I^2R$, since these are numerically equal, wouldn’t that mean all the power is dissipated as ...
- 13