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Why is the internal resistance of a voltage source made to be low?
Wiki User
∙ 12y ago
When a voltage source, such as a battery or a generator, is on open circuit -in other words, when it is not supplying a load- the voltage appearing across its terminals is called its 'open circuit voltage' and corresponds numerically to its electromotive force.
However, when the voltage source supplies current to a load, that current also passes through the voltage source itself. This causes an internal voltage drop, which is the product of this current and the voltage source's internal resistance. This voltage drop acts in the opposite direction to the electromotive force and reduces the source's terminal voltage. This internal voltage drop will increase, of course, if either the load current increases or the internal resistance increases.
So, in order to keep that the source's internal voltage drop is as low as possible, its internal resistance must be as low as possible. In the case of a battery, the internal resistance is due to the ionic resistance of the electrolyte/plates, whereas in a generator it is due to the resistance of the windings.
Wiki User
∙ 12y ago
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What happens to an electric current when the wire is made smaller?
Electric current as we usually describe it is the flow of electrons. Current is caused to flow by voltage, which can be looked at as "electrical pressure" that forces electrons to move. Currents can be made smaller or larger by decreasing the voltage across a fixed amount of resistance. As resistance is the quality of "resisting" or "limiting" current flow, we can change resistance to change current. For a give voltage, if we increase the resistance, we can make the current smaller, and if we decrease it, we can make current larger. In electronics, voltage equals current times resistance. E = I x R Also true is that current is equal to voltage divided by resistance. I = E/R As current equals volts divided by resistance, if we change one of them without changing the other, current will change. And in increase in voltage (with no change to resistance) will cause current to go up. The opposite is also true. Also, if we increase resistance (with no change in voltage), current will go down. And the opposite is true here, too.
What is electrical resistance used in glass for?
High voltage transmission line insulator are also made of glass.
How do you know the voltage drop of wire?
Voltage = Current x Resistance. To calculate the voltage drop of a piece of wire, you would have to know the current flowing in the circuit and the resistance of the wire. The resistance of wire depends on the material it is made of, the length, and the cross sectional area (also called gauge or AWG). Short thick wires have less resistance than long thin wires. You can look up the resistance of the wire on the Internet, and you can measure the current flowing by connecting an ammeter in series with the circuit. Multiply those two numbers and you will have closely approximated the voltage drop across the wire.
What does 5.6 kva equal in amps?
7.5kVA is a value derived from the voltage multiplied by the current. Without knowing one, you cannot know the other. For example, think of the number 10kVA This could be made by :10kV * 1A or 5kV * 2A or 1kV * 10A or 2kV * 5A. You couldn't possibly know which is the initial pair.
Why you use constant current source?
What follows below is not a full description. Full descriptions are in chapters of books about electronic power supplies.A constant current source is an electronic device which acts as a source of power whereby, however the load resistance changes - within a certain fixed range - the device is designed to monitor the output current drawn from it and will change its output voltage to keep the output current constant within a certain fixed range.Another answerA constant current source will provide constant current with a load if the load changes the volts will change to compensate for the constant current flowing. Which is just opposite to a constant voltage source whereby a load change will change the current but not the voltage. And that how it works.
Why do you get different results when calculating the voltage drop across a resistor and ignoring resistance of a voltmeter and when considering it?
Voltage drop is the product of current and resistance. When you connect a voltmeter across a resistor, you are connecting that voltmeter's internal resistance in parallel with that resistor. The resulting resistance of this parallel combination is lowerthan that of the resistor. As a result the voltage drop (current times this lower resistance) will be lower than it would be without the voltmeter connected. This is called the 'loading effect' of that voltmeter.The higher the internal resistance of the voltmeter, the less effect it will have on lowering the overall resistance when connected across a resistor. This is why the internal resistance of a voltmeter is made deliberately very high. Under most circumstances, therefore, a conventional voltmeter will have very little effect on the resistance of the circuit being tested and, so, it will have no significant effect on the voltage appearing across the resistor.However... for circuits that already have exceptionally-high resistance values, you must be careful when you select a voltmeter as you must take into account its internal resistance and ensure the voltmeter you use has the very highest internal resistance available. This is because the loading effect increases with circuits that have a high resistance. That might involve selecting a voltmeter that works on a completely-different principle , such as an electrostatic voltmeter or, perhaps, an oscilloscope
In what way the connections are made to get a higher output current from light?
A light doesn't output current, it "draws" current based on voltage and its resistance. Voltage = Current x Resistance or Current = Voltage / Resistance. (Ohm's Law)
Resistors of different value in series circuits have different voltages across them The relationship of resistance to voltage is?
A: A series Resistance network may have all kind of different value of resistors but the current will remain the same for each until an addition is made. While the current remains the same for each component the voltage drop across each will be different and all the sum of the voltage drop will equal the voltage source
What is the powder transfer theorem?
In electrical engineering, the maximum power (transfer) theorem states that, to obtain maximum external power from a source with a finite internal resistance, the resistance of the load must be made the same as that of the source. It is claimed that Moritz von Jacobi was first to discover the maximum power (transfer) theorem which is referred to as "Jacobi's law". The theorem applies to maximum power, and not maximum efficiency. If the resistance of the load is made larger than the resistance of the source, then efficiency is higher, since most of the power is generated in the load, but the overall power is lower since the total circuit resistance goes up. If the internal impedance is made larger than the load then most of the power ends up being dissipated in the source, and although the total power dissipated is higher, due to a lower circuit resistance, it turns out that the amount dissipated in the load is reduced.
What happens to an electric current when the wire is made smaller?
Electric current as we usually describe it is the flow of electrons. Current is caused to flow by voltage, which can be looked at as "electrical pressure" that forces electrons to move. Currents can be made smaller or larger by decreasing the voltage across a fixed amount of resistance. As resistance is the quality of "resisting" or "limiting" current flow, we can change resistance to change current. For a give voltage, if we increase the resistance, we can make the current smaller, and if we decrease it, we can make current larger. In electronics, voltage equals current times resistance. E = I x R Also true is that current is equal to voltage divided by resistance. I = E/R As current equals volts divided by resistance, if we change one of them without changing the other, current will change. And in increase in voltage (with no change to resistance) will cause current to go up. The opposite is also true. Also, if we increase resistance (with no change in voltage), current will go down. And the opposite is true here, too.
How can be a DC voltage source output voltage made half of its output voltgae?
By using something called a voltage divider.
Why an independent voltage source is made deactivated by shortening and an independent current source is made deactivated by open circuiting?
answer is "bobo kayo"
What is electrical resistance used in glass for?
High voltage transmission line insulator are also made of glass.
How much voltage is used to measure resistance?
The voltage needed to make a resistance measurement varies in proportion to the Ohms value being measured. Resistance measurements in the order of thousands and up to one Megohm are low enough to be made with a 1.5 volt or similar cell. However, resistance measurements in the order of hundreds to thousands of Megohm will require a higher voltage of up to 500 Volts DC. A Megger is a device that uses hundreds of volts to make resistance measurements.
How do you know the voltage drop of wire?
Voltage = Current x Resistance. To calculate the voltage drop of a piece of wire, you would have to know the current flowing in the circuit and the resistance of the wire. The resistance of wire depends on the material it is made of, the length, and the cross sectional area (also called gauge or AWG). Short thick wires have less resistance than long thin wires. You can look up the resistance of the wire on the Internet, and you can measure the current flowing by connecting an ammeter in series with the circuit. Multiply those two numbers and you will have closely approximated the voltage drop across the wire.
What does 5.6 kva equal in amps?
7.5kVA is a value derived from the voltage multiplied by the current. Without knowing one, you cannot know the other. For example, think of the number 10kVA This could be made by :10kV * 1A or 5kV * 2A or 1kV * 10A or 2kV * 5A. You couldn't possibly know which is the initial pair.
Why you use constant current source?
What follows below is not a full description. Full descriptions are in chapters of books about electronic power supplies.A constant current source is an electronic device which acts as a source of power whereby, however the load resistance changes - within a certain fixed range - the device is designed to monitor the output current drawn from it and will change its output voltage to keep the output current constant within a certain fixed range.Another answerA constant current source will provide constant current with a load if the load changes the volts will change to compensate for the constant current flowing. Which is just opposite to a constant voltage source whereby a load change will change the current but not the voltage. And that how it works.
