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What is the current flowing through a 200 watt resistor that has a rating of 21 ohms?
Wiki User
∙ 12y ago
The current can't be calculated from the information given in the question.
The power rating of a resistor is the maximum power it can dissipate before it overheats
and its resistance possibly changes permanently. The power rating is not the amount of
power it always dissipates.
So, all we really know about the resistor in the question is that its resistance is 21 ohms.
And all we can say about the current through it is:
Current through the resistor = (voltage between the ends of the resistor) divided by (21).
Wiki User
∙ 14y ago
Wiki User
∙ 12y agoWith the resistance (21 ohms) and power rating of the resistor (200-watts) given the value of current flowing through the resistor can be determined by dividing the power by resistance and then get the square-root of the quotient.
(I= 3.09)
This is the current value of the resistor if that what the question means. Without electromotive force given the exact value of current flowing though the resistor could not be determined with the given values above.
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What is the current through the 150 ohm resistor?
It depends on the voltage applied across it. But the maximum current is limited by the power-rating of the resistor (power divided by the square of the voltage).
What is the voltage drop across a 100 W resistor when the electric current flowing through it is measured at 250 mA?
Who can tell? The power rating of a resistor simply tells us the maximum power that resistor is capable of handling; it doesn't tell us anything about the actual power being produced for any given current. So, to find out the voltage drop across that resistor, you will need to find out its resistance, and multiply this value by the current you specify.
Cause of burnout of two resistor?
Too much current flowing in circuit. Sounds like a voltage was applied that exceeded the rating of the resistor. Resistors are rated in watts which is Volts times Amps. As an example, you might have a 1/2 watt rated resistor. If you applied 120 VAC across a 10 Ohm resistance then the current would be 12 Amps. The wattage would be 1,440 watts which is well in access of the rating and would certainly burn out the resistor.
To reduce the voltage, I need to change the voltage of 5v to 4.5v, I use a 30 ohm resistor, how many watts of resistor should I use?
To calculate the power rating of a resistor required to drop the voltage from 5V to 4.5V using a 30 ohm resistor, we can use the formula: Power = Voltage Drop x Current The current flowing through the resistor can be calculated using Ohm's law: Current = Voltage Drop / Resistance Substituting the values we get: Current = (5V - 4.5V) / 30 ohms = 0.0167 A (rounded to four significant figures) Now we can calculate the power required: Power = (5V - 4.5V) x 0.0167 A = 0.00835 watts So a resistor with a power rating of at least 0.00835 watts (or 8.35 milliwatts) should be sufficient for this application. However, it is recommended to use a resistor with a slightly higher power rating to ensure that it can handle any temporary power surges or variations in current that may occur. A 0.25 watt resistor should be suitable for this purpose.
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At what level will typical resistors burn out?
A typical resistor will burn out when it dissipates power in excess of double its power dissipation rating for an extended period of time. The power dissipated by a resistor is equal to I2R or E2/R, where E = the voltage across the resistor I = the current through the resistor R = the resistance of the resistor
How do you install a resistor in an DC circuit?
It depends on the purpose for installing the resistor. If the intent is to decrease current flow, the resistor must be connected in series with the load. If the purpose is to increase current flow, the resistor must be connected in parallel with the load. To connect a resistor in series, connect the resistor to one side of the power source, in line with the load. This will decrease circuit current flow. To connect a resistor in parallel, connect the resistor between the positive and negative sides of the power source, which will effectively connect the resistor across the load . This will increase current flow through the circuit. However, before connecting a component in parallel, make sure the increase in current flow will not exceed the current rating of the circuit or fuses/breakers will blow.
How are current ratings given to a resistor?
Resistors are not usually given 'current ratings' but, rather, 'power ratings' expressed in submultiples of the watt. It is then up to the user to calculate the safe maximum operating current for a particular resistor, by manipulating the equation: P = I2 R.Since a power rating is dependent upon the resistor's ability to dissipate energy by heat transfer, the actual power rating is dependent upon the surface area and, hence, the physical size of the resistor. So you will find that resistors come in a variety of physical sizes for any given resistance value.Unfortunately, power ratings are not indicated through colour codes, etc., so you will have to either specify its power rating when you purchase a resistor, or match your existing resistor against a scale-drawing to determine its power rating.
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Transformer rating is based on the maximum temperature a transformer can run at. This temperature is dictated by the amount of current flowing through the transformer windings. This is why transformers are rated in KVA (voltage * current), not kW - it doesn't matter what the phase relationship is between voltage and current, just the magnitude of the current.
How is the brightness of the LED affected by different resistor values?
LED's are light emmitting diodes. diodes have a voltage threshold that must be reached for them to fully "turn on". A resistor can be used to limit that voltage. As the voltage drop across the diode is increased above the turn on voltage (typically .5 - .7 volts), the diode will emmit light. The LED will only light up so far, so by turning the voltage up significantly more will have a very limitted payback in light output.
How much current flows through circuit breaker trip coil?
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What does 1 4W and 1 8W means for resistors and do they affect the value of the resistor?
It means the maximum power each one is capable of dissipating. The power dissipated by a resistor is (current through it)2 x (its resistance). If you exceed the power rating of a resistor, it will overheat, and that always increases its resistace value, at least for as long as it remains hot. If you take it to the extreme, the resistor can melt, smoke, crack, explode, etc. The power rating of a resistor has no direct effect on its resistance value.
