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Dalek1099

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In summary, the current increases when the voltage is increased, but this contradicts the equation that says that increasing the voltage decreases the current.

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Dalek1099

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berkeman

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Dalek1099 said:

Given a constant power, then increasing the voltage requires a drop in the current to maintain that constant power. It just depends on what you are trying to hold constant.

If you increase the voltage across a resistor, then both the current and power increase. V=IR and P=VI.

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Nugatory

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Dalek1099 said:I'm confused over this because generally I'm told that if the voltage increases then so does current and this satisfies the equation:V=IR because I=V/R increasing the top of the fraction should mean that the current increases but this contradicts the equation: P=IV because this time I=P/V and if you increase the voltage then the current should go down as is the rule with the bottom of the fraction.These two equations just don't make sense with each other-one equation says that increasing the voltage increases the current and the other says that increasing the voltage decreases the current.

If you increase V, then I and P both increase. You can't hold P fixed when I and V are changing and R is being held constant.

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berkeman

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Now, as you raise the input voltage Vin, the input current Iin drops. It's a very common characteristic for DC-DC converters,

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Dalek1099

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berkeman said:Given a constant power, then increasing the voltage requires a drop in the current to maintain that constant power. It just depends on what you are trying to hold constant.

If you increase the voltage across a resistor, then both the current and power increase. V=IR and P=VI.

I think I get it now because you can't change one thing and keep 2 other things constant.

- #6

CWatters

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this time I=P/V and if you increase the voltage then the current should go down as is the rule with the bottom of the fraction.

What you have said is only true if P is constant. All three terms (P, I and V) are normally variables.

In most but not all circuits if you increase V then both I and P will also increase.

For a resistive circuit:

I = V/R

and

P = V

By inspection it's clear that if you change V then P increases faster than I.

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sophiecentaur

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Dalek1099 said:

The equations in Science are only ways of working things out. Like the rest of life, it's GIGO. Equations do not necessarily show which is cause and which is effect. You could probably have equally odd conclusions out of speed, time and acceleration equations if you were not so familiar with them.

When a higher voltage is applied to a circuit, the current will also increase. This is because an increase in voltage creates a larger potential difference, which allows for more electrons to flow through the circuit.

Yes, in most cases, the current will increase with a higher voltage. However, if the circuit has a fixed resistance, the current may remain the same as the increase in voltage would not affect the flow of electrons.

Yes, there is a limit to how much the current can increase with a higher voltage. This limit is determined by the resistance in the circuit. As the resistance increases, the current will decrease, even with a higher voltage.

Yes, a higher voltage can damage components in a circuit. If the voltage is too high, it can cause the components to overheat and potentially lead to a short circuit. It is important to use the appropriate voltage for each component in a circuit.

The length of a wire can affect the relationship between voltage and current. A longer wire will have a higher resistance, which means that a higher voltage will be needed to maintain the same current in the circuit. This is known as the voltage drop and can be calculated using Ohm's law.

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