1 Alternating Current and RLC Circuits Alternating Current: the current direction changes with time....
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1 Alternating Current and RLC Circuits Alternating Current: the current direction changes with time. Compare with DC in which the current direction stays the same with re spect to time, the magnitude of the current may change. A typical case in AC: I = I MAX SIN(ωt). A power source normally is descri bed as V = V MAX SIN(ωt). Generation: rotating wire loops in magnetic field generate AC power. (demo: 32.18) Main advantages: for power generation (actually the magnet turns) and transmission. Review: DC on RC and RL circuit, and now pay attention to the cu rrent/voltage relationship in time. RC ) t ( V ) t ( BA dt d B SIN SIN max External torque turns the wire loop at an angular velocity ω. The magnetic f lux through this loop is Φ B = BACOS(ωt) So the induced emf is When this emf is applied to a resistor, from Ohm’s Law, the current through t his resistor is I = I MAX SIN(ωt), With I MAX = V MAX /R.
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Transcript of 1 Alternating Current and RLC Circuits Alternating Current: the current direction changes with time....
1
Alternating Current and RLC Circuits
Alternating Current: the current direction changes with time. Compare with DC in which the current direction stays the same with respect to time, the magn
itude of the current may change. A typical case in AC: I = IMAXSIN(ωt). A power source normally is described as V = VMAXSIN(ωt).
Generation: rotating wire loops in magnetic field generate AC power. (demo: 32.18)
Main advantages: for power generation (actually the magnet turns) and transmission.
Review: DC on RC and RL circuit, and now pay attention to the current/voltage relationship in time. RC
)t(V)t(BAdt
d B SINSIN max
External torque turns the wire loop at an angular velocity ω. The magnetic flux through this loop is
ΦB = BACOS(ωt)
So the induced emf is
When this emf is applied to a resistor, from Ohm’s Law, the current through this resistor isI = IMAXSIN(ωt), With IMAX = VMAX/R.
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Alternating Current and RLC Circuits
Review: DC on RC and RL circuit, and now pay attention to the current/voltage relationship in time. RL
R C L
Current Rise/fall w/ voltage Leads voltage lags behind voltage
Voltage Same time w/ current lags behind current leads current
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Alternating Current and RLC Circuits
R, C and L in AC circuits: R
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Example
An electric stove is specified as 6000W at 240V. If it is connected to an AC outlet in a laboratory. The AC outlet has a sticker reads V = 311SIN(100πt). What is heat the stove generates in 10 seconds?
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Alternating Current and RLC Circuits
R, C and L in AC circuits: C
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example
The generator in an AC capacitor circuit creates a maximum potential difference across the 3.37×10−6 F capacitor of 243 V. What is the amplitude of the alternating current if the frequency of the generator is (a) 455 Hz? (b) 1750 Hz?
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Alternating Current and RLC Circuits
R, C and L in AC circuits: L
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example
The generator in an AC inductor circuit creates a maximum potential difference across the 2.74×10−3 H inductor of 243 V. What is the amplitude of the alternating current if the frequency of the generator is (a) 455 Hz? (b) 1750 Hz?
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Alternating Current and RLC Circuits
Review of LC and beyond: LC oscillator
Energy in LC oscillator
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Alternating Current and RLC Circuits
Review of LC and beyond: LC in AS circuits.
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Alternating Current and RLC Circuits
Add R to LC: RLC in AC circuits
