capacitors and/or tv ( not emf)
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Capacitors and/or TV ( not Emf). RC CIRCUITS. 1. An empty capacitor does not resist the flow of current, and thus acts like a wire . 2. A capacitor that is full of charge will not allow current to flow, and thus acts like a broken wire . RC Circuits. - PowerPoint PPT PresentationTRANSCRIPT
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Capacitors and/or TV (not Emf)
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1. An empty capacitor does not resist the flow of current, and thus acts like a wire.
2. A capacitor that is full of charge will not allow current to flow, and thus acts like a broken wire.
RC CIRCUITS
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When the switch is closed, the capacitor will begin to charge.
RC Circuits
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If an isolated charged capacitor is connected across a resistor, it discharges:
RC Circuits
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A battery with an emf of 24 V and an internal resistance of 1 Ω is connected to an external circuit as shown above.
1990B3p.47
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a.Calculate the equivalent resistance of the combination of the 4Ω, 8Ω, and 12Ω resistors
RS = 4 + 8 = 12 Ω 11 1
12 12PR
= 6 Ω
1990B3 p.47
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1990B3 p.47
b.Calculate the current in the 5 Ω resistor
RE = 5 + 1 + 6 = 12 Ω
E
VIR
= 2 A
24 V12
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c. Calculate the terminal voltage, VAC of the battery
VT = E - I r = 24 V - (2 A) (1 Ω)
= 22 V
1990B3 p.47
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d. Calculate the rate at which energy is dissipated in the 12 Ω resistor
P = I2 R = (1 A)2 (12 Ω) = 12 W
Current splits at B with 1 A through each branch
1990B3 p.47
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e. Calculate the magnitude of the potential difference VBC
VBC = I R = (2 A) (6) Ω = 12 V
1990B3 p.47
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In the circuit shown above, A, B. C, and D are identical light bulbs. Assume that the battery maintains a constant potential difference between its terminals (i.e., the internal resistance of the battery is assumed to be negligible) and the resistance of each light bulb remains constant.
1998B4p.58
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a. Draw a diagram of the circuit in the box , using the symbols to represent the components in your diagram. Label the resistors A, B. C, and D to refer to the corresponding light bulbs.
1998B4 p.58
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b. List the bulbs in order of brightness, from brightest to least bright. If any two or more bulbs have the same brightness, state which ones. Justify your answer.A > D > B = CA has the largest currentVD = VC + VB
so D is brighter than C or BC and B are in series = same current
1998B4 p.58
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c. Bulb D is then removed from its socket.
i. Describe the change in the brightness, if any, of bulb A when bulb D is removed from its socket. Justify your answer.The brightness of bulb A
decreases.REq increases, IA decreases
1998B4 p.58
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ii. Describe the change in the brightness, if any, of bulb B when bulb D is removed from its socket. Justify your answer.The brightness of bulb B increases.The current through bulb B increases, voltage across B increases
1998B4 p.58
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A circuit contains two resistors (10 Ω and 20 Ω) and two capacitors (12 μF and 6 μF) connected to a 6 V battery, as shown in the diagram above. The circuit has been connected for a long time.
2003B2
p.47
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a. Calculate the total capacitance of the circuit.
1
1 2
1 1TC C C
1
6 6
1 112 10 F 6 10 F
= 4x10-6 F
2003B2 p.47
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b. Calculate the current in the 10 Ω resistor.
1 2ER R R 10 20 30
E
VIR
6 V30 ½
= 0.2 A
2003B2 p.47
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c.Calculate the potential difference between points A and B.VAB = V20 = IR20
= (0.2 A)(20 Ω) = 4 V
2003B2 p.47
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d.Calculate the charge stored on one plate of the 6 μF capacitor.
Q = CTV = 4x10-6 F (4 V) = 16x10-6 C
2003B2 p.47
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e.The wire is cut at point P. Will the potential difference between points A and B increase, decrease, or remain the same? Justify your answer.___increase ___decrease ___remain the same No current flows through A-B so
it does not affect the potential
difference
2003B2 p.47