A 40W instrument has a resistance 90 Ohms. On what voltage should it be operated normally
-
60V
- 150V
- 225V
- 360V
The correct answer is: A
Explanation
P = 40W
R = 90W
V = ?
P = \(\frac{V^2}{R}\)
V\(^2\) = PR = 40 x 90
V\(^2\) = 3000
V = √3600
V = 60N
There is an explanation video available .