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?
1/4 watt
1/2 watt
1 watt
2 watts
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
16 comments Page 1 of 2.

Thea said:   4 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.

Rajesh said:   5 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.
(2)

Gopala said:   5 years ago
Explain how it come 1/4?

Gopal said:   5 years ago
I am not getting the solution. Please explain it.

Engr Faizan Rais said:   6 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.
(2)

Soni said:   7 years ago
P= IV, P=I*I*R.
1*10^-3*10^-3*470,
=0.00047w.
(1)

Vignesh said:   7 years ago
Here, the m value is 10^-3 then how to get the answer 1/4?

Fred Simz Jr said:   7 years ago
I can't understand how 0.25w came?

Please explain.

Lewis said:   8 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.

A.sathish said:   8 years ago
0.00047w is correct, which is the nearest value.


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