Electronics - Resistance and Power - Discussion
Discussion Forum : Resistance and Power - General Questions (Q.No. 5)
5.
With 1 mA of current, what wattage rating should a 470 ohm resistor have?
Discussion:
16 comments Page 1 of 2.
Thea said:
5 years ago
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.
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.
Rathi said:
1 decade ago
@Manikanta.
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.
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.
Lewis said:
9 years ago
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.
Engr Faizan Rais said:
7 years ago
p=i^2*R.
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.
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.
(2)
Rajesh said:
6 years ago
0.00047 less than 1/4 watt so least one is 1/4 watt is right answer.
1000mW = 1W, 0.250W is correct.
1000mW = 1W, 0.250W is correct.
(2)
Manikanta said:
1 decade ago
P=I^2R, So
P = 1*10^-6*470 = 0.00047W. How will come 1/4. Please explain?
P = 1*10^-6*470 = 0.00047W. How will come 1/4. Please explain?
Vignesh said:
8 years ago
Here, the m value is 10^-3 then how to get the answer 1/4?
Theophillus said:
1 decade ago
I don't understand how did you get 0.25 W there seriously.
Fred Simz Jr said:
9 years ago
I can't understand how 0.25w came?
Please explain.
Please explain.
Gopal said:
6 years ago
I am not getting the solution. Please explain it.
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