JAMB - Physics (1993 - No. 30)
A 40-W instrument has a resistance of 90\(\Omega\). On what voltage should it be operated normally?
60V
150V
225V
3600V
คำอธิบาย
P = \(\frac{V}{R}\)
V = \(\sqrt{PR}\)
V = \(\sqrt{40 \times 90}\)
= 60V
V = \(\sqrt{PR}\)
V = \(\sqrt{40 \times 90}\)
= 60V