A 40W instrument has a resistance 90 Ohms. On what voltage should it be operated normally
A
60V
B
150V
C
225V
D
360V
Verified Correct Answer: A.
Physical Principles & Numerical Solution
P = 40W
R = 90W
V = ?
P = \(\frac{V^2}{R}\)
V\(^2\) = PR = 40 x 90
V\(^2\) = 3000
V = \sqrt3600
V = 60N
Source: Myschool Past Questions Archive (Record #47726)