Discussion :: Resistance and Power - General Questions (Q.No.5)
With 1 mA of current, what wattage rating should a 470 ohm resistor have?
Answer: Option A
No answer description available for this question.
|Manikanta said: (Apr 19, 2012)|
P = 1*10^-6*470 = 0.00047W. How will come 1/4. Please explain?
|Rathi said: (Apr 19, 2012)|
Yes you are right.
But we should take the wattage of the resistance greater than calculated value.
0.25(i.e 1/4) is greater than 0.00047W, So 1/4 is enough.
That means 1/4 watt is the right answer.
Note: If 1/8watt is given in option then 1/8 will be the correct answer.
|Domy Dimal said: (Oct 22, 2014)|
|0.25 w is greater than 0.00047w. Then how?|
|Theophillus said: (May 7, 2015)|
|I don't understand how did you get 0.25 W there seriously.|
|Vasava said: (Aug 31, 2015)|
|I can't understand how it come 0.25 watt?|
|Priyank Sharma said: (Jun 2, 2016)|
|Why its answer is 0.25watt?|
|A.Sathish said: (Jun 29, 2016)|
|0.00047w is correct, which is the nearest value.|
|Lewis said: (Aug 19, 2016)|
|On our resistor wattage we have 1/8W, 1/4W, 1/2W, 1W,2W so when we rate we take the closest to 0.00047W which is the 0.25W. If there was the 0.125 W(1/8) resistor would be more suitable.|
|Fred Simz Jr said: (Feb 9, 2017)|
|I can't understand how 0.25w came?
|Vignesh said: (Apr 11, 2017)|
|Here, the m value is 10^-3 then how to get the answer 1/4?|
|Soni said: (Sep 16, 2017)|
|P= IV, P=I*I*R.
|Engr Faizan Rais said: (Sep 28, 2018)|
So putting the values:
p = (40mA)^2*470
p = 0.751W
So, 0.751 w is nearer value to 1 w, the ans is 1 watt.
|Gopal said: (Sep 17, 2019)|
|I am not getting the solution. Please explain it.|
|Gopala said: (Sep 17, 2019)|
|Explain how it come 1/4?|
|Rajesh said: (Oct 4, 2019)|
|0.00047 less than 1/4 watt so least one is 1/4 watt is right answer.
1000mW = 1W, 0.250W is correct.
|Thea said: (Apr 11, 2020)|
|1/4 watts, 1/2 watts or 1 watts means the physical size of the resistor and not the technical measures.
1/4 watts means the resistor physical size is smaller. This usually uses in experiments or another device that handle a small amount of power.
And 1 watt means the physical size of the resistor is bigger and usually use in high power use to be not destroyed immediately by the current flowing.
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