254 Chapt. 33 Alternating Current or AC power equality result to derive the relationship between the primary current I p and the secondary current I s . Assume that the power in both coils obeys P = I Δ V , where I is the current through the device and Δ V is the potential change across the device (which for ideal coils is the emf). c) Find the formula that relates N p , I p N s , and I s . Then give a combined ratio formula for number of coil turns, coil emfs, and coil currents. 033 qfull 00610 1 3 0 easy math: transformer power e±ciency 4. Using high transmission potential and low transmission current is energy e±cient: their is less energy lost in heating the transmission wires. a) A power station outputs power P at (RMS) potential E . The transmission wire has resistance R . The power lost to heat in the wire is P loss Find the formula for relative power loss P loss /P in terms of P , R , and E . HINT: Assume potential and current are in phase: i.e., assume that the formula P
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