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Electric Currents (R)

Electric Currents (R). Resistors (L). circuit symbol. what is the resistance of this resistor?. Try some others. Electric Power (L). Power = Energy / time. Other useful forms:. Think-Pair-Share (L).

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Electric Currents (R)

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  1. Electric Currents (R) Current & Resistance

  2. Resistors (L) circuit symbol what is the resistance of this resistor? Try some others. Current & Resistance

  3. Electric Power (L) • Power = Energy / time Other useful forms: Current & Resistance

  4. Think-Pair-Share (L) • You buy a 75-W lightbulb in Europe, where electricity is delivered to homes at 240 V. If you use the lightbulb in the US at 120 V (assume its resistance does not change), how bright will it be relative to 75-W 120-V bulbs? [Hint: assume that brightness is proportional to power consumed.] Current & Resistance

  5. Think-Pair-Share (L) • How many kWh of energy does a 550-W toaster use in the morning if it is in operation for a total of 15 min? At a cost of 9.0 cents/kWh, estimate how much this would add to your monthly electric bill if you made toast four mornings per week. Current & Resistance

  6. Power in Household Circuits (L) • Wires heat up at a rate equal to I2R(power) • fire hazard if I is too large • fuses prevent overloads by breaking circuit • short - two wires touching Current & Resistance

  7. Fuses (L) fuses that need to be replaced circuit breaker- breaks circuit with a switch Current & Resistance

  8. Household Circuits (L) • What is the total current draw by these devices? If the circuit has a 20-A fuse, will the fuse blow? Current & Resistance

  9. Alternating Current (L) • DC • direct current • current is constant • AC • alternating current • current varies like a sine wave • frequency usually 60 Hz (60 cycles per second) • Equations are valid when you use RMS values Current & Resistance

  10. Human Nervous System (L) Messages transmitted within nervous system are electrical signals passing along the neuron Current & Resistance

  11. Practice Problems • Determine the equivalent resistance and the current through R1 for the circuits shown. Assume R1 = 10, R2 = 20 , and R1 = 30 , and the battery is 12 V. Circuits

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