Electrical Engineering - Energy and Power - Discussion
Discussion Forum : Energy and Power - General Questions (Q.No. 9)
9.
A 120 
resistor must carry a maximum current of 25 mA. Its rating should be at least
resistor must carry a maximum current of 25 mA. Its rating should be at leastDiscussion:
59 comments Page 3 of 6.
Sharmila said:
9 years ago
150mw is wrong answer.
Because the given current is in maximum value, how you can multiple with root 2?
The formula is v (r.m.s) = [v(max.)/root 2]. So,the answer is 75mw.
Because the given current is in maximum value, how you can multiple with root 2?
The formula is v (r.m.s) = [v(max.)/root 2]. So,the answer is 75mw.
Supriyo said:
9 years ago
I too think 75mw is the correct answer.
Pratik suhas gajengi said:
9 years ago
You are right @R N Trimukhe.
Ravi ranjan said:
8 years ago
P=i2r bit here I is the RMS and irms =I'm/√2 now apply 25ma square * 120 * 2 = 150mw.
Rishipal said:
8 years ago
D is correct because maximum current is given it is not RMS current so, it changes in RMS current.
RMS current=maximum current/root2. Then power = i2r.
RMS current=maximum current/root2. Then power = i2r.
Rabindra Singh said:
8 years ago
150mA is the correct answer.
Given current is the rms value, and the rating must be decided on maximum current.
Imax = Irms * sqrt2 = 25mA * sqrt2 = 0.0353,
Hence rating =(Imax)^2 *120 = 150mW.
Given current is the rms value, and the rating must be decided on maximum current.
Imax = Irms * sqrt2 = 25mA * sqrt2 = 0.0353,
Hence rating =(Imax)^2 *120 = 150mW.
S.Mohamed said:
8 years ago
Thanks @Pranav.
Yashmendr Tiwari said:
8 years ago
@All.
The concept of max and rms fundamental is not right bz max current already given
then why you are calculate Imax = Irms * sqrt2 = 25mA * sqrt2 = 0.0353?
Please explain me.
The concept of max and rms fundamental is not right bz max current already given
then why you are calculate Imax = Irms * sqrt2 = 25mA * sqrt2 = 0.0353?
Please explain me.
Bibek said:
7 years ago
I think 75 mW is the correct answer.
Sam said:
6 years ago
Yes it should be at least greater than the rated value.
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