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Assume a device draws 50ma of current and 150vdc across it what is its resistance?
Wiki User
∙ 14y ago
Ohm's law: Voltage = Current times Resistance Solve: Resistance = Voltage divided by Current So, a device drawing 50ma with 150V has a resistance of 150 / 0.05, or 3000 ohms. p.s. Since power is volts times amps, that device is dissipating 7.5 watts.
Wiki User
∙ 14y ago
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How does a resistor resist electric current?
A resistor works by limiting the current that goes through it. When current is limited, then voltage across the resistor also changes. We use many forms of resistors in our normal day. Lightbulbs are infact all resistors in one way or another. When the filament in a lightbulb heats up, the resistance increases. When resistance increases, the current is reduced. In the end, the current has been reduced so much that it can no longer carry on heating up the filament. The bulb is then thermally stable and shines for our pleasure.
How does the potential difference across the light when batteries are added in series compare to parallel?
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What is the purpose of a variable?
A variable resistor is used in cicuits to vary the current passing through the resistor. It is commonly used to change the value of current across a circuit, or to act as a voltage divider. They are commonly equiped with a knob outside of a cabinet, to enable the user to adjust the operation of a circuit, like a volume control on a radio or amplifier.
What resistors are required to convert 12volts Dc to 3 volts dc?
In general terms, the voltage across a resistor can be calculated by ohms law: V = I . R voltage across the resistor = current through the resistor multiplied by the value of the resistor. So, if the resistor has a value of 100 ohms and the current flowing through the resistor is 10mA then the voltage across the resistor will be 100 x 0.01 = 1 volt. If the current flows through two resistors connected in series, the voltage will be split over the two resistors according to their resistance. V = V1+V2 = I . R1 + I . R2 You want V2/(V1+V2)=3V/12V Using Ohm's law for each voltage: V2/(V1+V2) = I . R2 / (I . R1 + I . R2) = R2 / (R1+R2) You see that the answer to your question is: Any combination of resistors will do the job, provided that R2/(R1+R2) = 3V/12V e.g. R2=3Ohm and R1=8Ohm or R2=3000Ohm and R1=8000Ohm Depending on your choice, you will get a different current flowing. In the real world you might need to control the current flowing into your circuit. For example if the device to be powered is a 3V LED and the required current is 15mA then we can calculate as follows: 12V - 3V = 9V. 9V = 0.015A x R Therefore R = 9V / 0.015A Therefore R = 600 ohms. However, in real life this is usually a terrible way to control voltage for several reasons. First, because the current in the most circuits is not constant (it would be constant for an LED but not for most gadgets). Second, this method wastes energy heating the resistor. Third, it is often not possible to find a resistor of exactly the right value. So, in real life this problem is usually solved by using a "voltage regulator" which is a simple integrated circuit (often with just three legs).
Why TRIACS blow?
You exceed the power dissipation capability of the device and it burns up. Too much voltage across the terminals , too much current being passed through it, reverse voltage spikes can all cause the triac to "blow".
What is a IR drop across a resistance?
IR drop across a resistance is voltage. The letter I means current, and the letter R means resistance. Current times resistance, by Ohm's law is voltage.
How is a current affected across a wire if its resistance increases?
As the resistance increases the temperature will also increases....
Voltage across resistor is doubled the current is?
Ohm's law states that the voltage across a resistor is the product of the current times the Resistance or V=I x R (I times R). V is Voltage, R is Resistance, and I is Current or Amperage. So if the Voltage is doubled and Resistance stays the same, the Current will be doubled.
What happens with electric current when applying the same voltage the resistance of the circuit is reduced?
As the resistance is reduced across the same voltage, the current increases.
Why does higher resistance have a larger voltage drop across it?
In a d.c. circuit, voltage drop is the product of resistance and current through that resistance.
What happens to current in a circuit if the voltage is halved and the resistance stays the same?
the current doubles.. explanation:V=IR hence I=V/R which means that when the supply voltage is constant ,current is inversely proportional to resistance.thus the current doubles. practically speaking when the resistance of the load(fan ,bulb,refrigerator,....) is less ,it draws more current from the source so as to balance the voltage across it.i.e; to maintain the voltage across it as constant. This answer is absolutely correct if you assume that the current comes from a pure voltage source ( voltage source with zero internal resistance). At the other extreme you could have a current source (such as a very large voltage source in series with a very large resistor), and then the current is practically independent of changes if the external resistance is changed (because the change represents a relatively minute change in the overall resistance). With appropriate circuitry it is possible to devise a situation where the current is practically independent of the changing resistance.
What is the effect on the current in a wire if both the voltage across it and it's resistance are doubled?
By Ohm's Law, current is voltage divided by resistance, so if you double both the voltage and the resistance, the current would remain the same.
A dc voltage source of 10V is in parallel with a current source of 5A and a resistance of 1 ohm what will be the current across the resistance?
use kvl or kcl
Ac voltage applied across a load resistance produce alternating current?
The reason an AC voltage applied across a load resistance produces alternating current is because when you have AC voltage you have to have AC current. If DC voltage is applied, DC current is produced.
What are those different power ratings for the same resistance?
The amount of current that will pass through a resistance is dependant upon the voltage applied across the resistance. Voltage devided by resistance equals current. This is Ohm's Law.
How much current 2.2 Megohm?
"Ohm" and its multiples is not a unit of current."Ampere" and its multiples is.The current through a 2.2-megohm resistance is(the voltage across the resistance)/(2,200,000) amperes .
How do you measure alternating current voltage and resistance?
You measure current by inserting an amp meter in series with the circuit or using a clamp-on meter to measure current by induction. You measure voltage with a volt meter across the supply. You measure resistance in ohms across the resistance. Luckily all these functions are in the same meter in most cases.
