menentukan rumus daya

.........W
P = ------
..........t

.......I^2 × R × t
P = ---------------
...............t

........V × I × t
P = -------------
...............t

P = V × I
P = I^2 × R

P = Daya (Joule/detik atau Watt)
W = Usaha (Joule)
V = Beda potensial (Volt)
I = Kuat arus (Ampere)
R = Hambatan (Ohm)
t = waktu (detik atau sekon)