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- PHY102 Physics II © Dr.Cem Özdoğan
- 26-7 Power in Electric Circuits
- Example: A P=1250 Watt radiant heater is constructed to operate at V=115Volts.
- What is the resistance of the heating coil?
- What will be the current in the heater?
- How much thermal energy is produced in 1.0 hr by the heater?
- Formulas: P=i2R=V2/R; V=iR
- Know P, V; need R to calculate current!
- P=1250W; V=115V => R=V2/P=(115V)2/1250W=10.6 Ω
- i=V/R= 115V/10.6 Ω=10.8 A
- P=dU/dt => ΔU=P×Δt = 1.250kW•hr = 1250W × 3600 sec= 4.5 MJ