Electricity Question Amps & volts confusion

[Barclay]

Homework Statement

[/B]
A) If a laptop computer charger is designed for use in a country where mains voltage is 230V. Will the user still be able to charge the laptop computer in a country where the mains supply is 110V?
B) Also what happens if a 110V charger is used in a country where the mains electricity is 230V?

Homework Equations

[/B]
I don't think there are any particular equations to consider but the equations for other questions in this topic have been : P=VI (Power of an appliance in watts = voltage x amps) and also E = VIt (Energy transferred = volts x amps x time)

The Attempt at a Solution

In A) the charger may not work at all or charge very poorly because the transformer will reduce the CURRENT (or MAINS voltage??) by the same factor for either the 230V supply or the 110V supply. So because the person is in the 110V country there may not be enough current (amps) to charge the charger.

In B) there may be too much current (or voltage??) entering the device via the transformer so may damage the device (though the device may work at first). Later the device may overheat. The fuse may blow at the socket anyway, even before the current reaches the charger.

I'm quite confused about VOLTS and AMPS. I think AMPS and VOLTS belong in this answer and I think I've talked about the terms correctly but am not sure.

Thank you

 

[phinds]

Transformers do not change current directly but only as a result of their basic function which is to change the voltage.

You are basically right in your statements except that you ascribe to the transformer current properties which it does not have.

Take a step-down transformer (which charger transformers are). The output voltage is a fixed ratio of the input voltage. Say 12V out for 120V in. That means that an input voltage of 220V will produce an output voltage of 24V. What that does to the current depends on the load. A passive load such as a pure resistor will simple take on the amount of current given by Ohm's Law. An ACTIVE load such as a power supply circuit of some kind (usually with diodes and transistors) will act differently but you need to know the specific circuit to tell just what it will do.

You should look up and study "step-up" and "step-down" transformers to get a feel for this.

 

[Barclay]

Thanks Phinds. Based on your advice my modified answer is:

In A) the charger may not work at all or charge very poorly / slowly because the transformer will reduce the MAINS VOLTAGE by the same factor for either the 230V supply or the 110V supply. So because the person is in the 110V country there may not be enough VOLTAGE to charge the charger.

In B) there may be too much VOLTAGE entering the device via the transformer so may damage the device. The device may work at first but later the device may overheat. The fuse may blow at the socket anyway, even before the current reaches the charger.

Is that last sentence about the fusing blowing correct?

Also is the current charging the charger or the voltage?I didn't understand this:

"What that does to the current depends on the load. A passive load such as a pure resistor will simple take on the amount of current given by Ohm's Law. An ACTIVE load such as a power supply circuit of some kind (usually with diodes and transistors) will act differently but you need to know the specific circuit to tell just what it will do".

 

[phinds]

Thanks Phinds. Based on your advice my modified answer is:

In A) the charger may not work at all or charge very poorly / slowly because the transformer will reduce the MAINS VOLTAGE by the same factor for either the 230V supply or the 110V supply. So because the person is in the 110V country there may not be enough VOLTAGE to charge the charger.

In B) there may be too much VOLTAGE entering the device via the transformer so may damage the device. The device may work at first but later the device may overheat. The fuse may blow at the socket anyway, even before the current reaches the charger.

Is that last sentence about the fusing blowing correct?

yes

Also is the current charging the charger or the voltage?

The current is doing the charging, but the current is a function of the voltage.

I didn't understand this:

"What that does to the current depends on the load. A passive load such as a pure resistor will simple take on the amount of current given by Ohm's Law. An ACTIVE load such as a power supply circuit of some kind (usually with diodes and transistors) will act differently but you need to know the specific circuit to tell just what it will do".

Study circuits. I'm not up for writing a course on basic circuits.

 

[HalfLostAndSearching]

for your question. It is understandable to be confused about the concepts of volts and amps, as they are both important components of electricity. To clarify, volts measure the electrical potential difference between two points, while amps measure the flow of electrical current. In other words, volts determine the force that makes electricity move, while amps measure the actual movement of electricity.

In regards to the laptop charger question, it is important to consider the voltage and current ratings of the charger. The charger is designed to operate at a specific voltage and current, and using it in a country with a different mains voltage can potentially damage the charger. In the first scenario, where the charger is used in a country with a lower mains voltage, the charger may not be able to draw enough current to charge the laptop properly, as the lower voltage would result in a lower current. In the second scenario, where the charger is used in a country with a higher mains voltage, the charger may draw too much current, potentially damaging the charger and the laptop.

Therefore, it is important to use chargers that are specifically designed for the mains voltage of the country you are in. It is also important to note that some chargers have a voltage switch that allows them to be used in different countries with different mains voltages. It is always best to check the voltage rating of your charger and make sure it is compatible with the mains voltage of the country you are in to avoid any potential damage or malfunction.