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 2 of 2.
Soni said:
8 years ago
P= IV, P=I*I*R.
1*10^-3*10^-3*470,
=0.00047w.
1*10^-3*10^-3*470,
=0.00047w.
(1)
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)
Gopal said:
6 years ago
I am not getting the solution. Please explain it.
Gopala said:
6 years ago
Explain how it come 1/4?
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)
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.
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