How many watts are consumed when a current of 7.0 milliamperes flows through a 1,250-ohm resistance?
Why Use P = I squared times R when you know current and resistance. Convert first: 7.0 mA = 0.0070 A, and 0.0070 squared = 0.000049 A squared. Multiply by 1,250 ohms and you get 0.061 W, which is about 61 milliwatts.
Watch out The choice reading 61 watts has the right arithmetic but the wrong scale: a few milliamps through a kilohm is a tiny amount of power, so the answer has to land in the milliwatt range.
P = I²R. Convert mA to amps first, or you will be off by a million.
7 squared is 49, times 1250 is 61,250. Milliamps squared cost you six zeros, landing on 61 milliwatts.