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Each bulb is connected to the same potential difference, that of the battery, so they all have _____ ______ brightness.
In the second circuit, the battery must power two light bulbs, so it provides twice as much _______
- the same
- current
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50 and 100 ohms are in series and the 75 ohm resistor is parallel so A.
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- The second is parallel so it uses more current, however, the brightness is equal.
- E.) A = B = C
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A. the light bulb connected to 110V has 60 W and 100 W respectively. Thus, 60W has a higher resistance than 100W from P = V2/R
Next, they are now connected in series, so same amount of current pass through both bulbs. The one with higher resistance will dissipate more power (P = I2R). Thus, the 60 W bulb will dissipate more power than the other one. So, should be brighter.
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B. V2/R because its in a parallel configuration, the resistors have the same potential.
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- Ohm's Law:
- I = V/Req = V/(R1 + R2 +R3)
- 1.0 = 9/(3 + 2.5 + R3)
- 1.0 = 9/(5.5 + R3)
- 5.5 + R3 = 9
- R3 = 9 - 5.5
- R3 = 3.5 Ω
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- Calculations for left circuit:
- Req= 36 Ω
- Current through circuit:
- I= V/R= 9/36= 0.25 A
Power: P= I 2R= 0.25*0.25* 36= 2.25 W
- Calculations for right circuit:
- Req = 18*18/(18+18)= 9 Ω
- Current through circuit:
- I = V/R= 9/9= 1 A
- Power:
- P= I2R = 1*1* 9= 9 W
Power of right circuit is more than power of left circuit.
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A circuit consisting of resistors can often be reduced to a simple circuit containing only one resistor. State the 4-step process
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If the current in or the potential across a resistor in the initial circuit is to be found, start with the ______ ______ and gradually work your way back through the ______ ______.
Find currents and voltages across resistors using ΔV = ____ and your understanding of ______ and ______ _______
- final circuit
- equivalent circuits
- ΔV = IR
- series and parallel combinations
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Household circuits are always wired so that the electrical devices are connected in _______.
☞Each device operates _______ of the others so that if one is switched off, the other remains on
☞Each device operates on the same _______
- parallel
- independently
- voltage
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If devices were connected in _____, the voltage applied to the combination would divide among the devices
The _______ applied to any one device would depend on how many devices were in combination
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1. Safety fuses
☑ Wires melt when current is ________
☑ Connected in _______ along supply line to prevent overloading
☑ Commonly replaced by ______ ______
2. Circuit breaker
☑ Circuit breakers are used in ______ with other circuit elements for safety purposes
☑ A circuit breaker is designed to switch off and open the circuit at some _______ ______
☑ If a circuit breaker were not used, large currents caused by ______ _____ many devices could result in excessive ________ in wires and perhaps, cause a fire
- excessive
- series
- circuit breakers
- series
- maximum current
- turning on
- temperatures
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Device that measures the current in a circuit element is a(n) ________. An ammeter must be placed _____ ______ with the circuit element whose current is to be measured.
The ammeter's resistance must be much less than R in order for it to not change the ______ of the circuit
The resistance of an ideal ammeter is _____ so that it can measure the current without _______ the current
What happens if you accidentally connect the ammeter in parallel?
- ammeter
- in series
- current
- zero
- changing
- device will short circuit
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A device that measures the potential difference across a circuit element is a _______.
A voltmeter must be placed in ______ with the circuit element whose _______ _______ is to be measured.
The voltmeter's resistance must be much _______ than R in order not to affect the circuit
An ideal voltmeter has _______ resistance so that it can measure the voltage without _______ the voltage
- voltmeter
- parallel
- potential difference
- larger
- infinite
- changing
- **Note: 1/Req = 1/R1 + 1/Rvoltmeter (very big/close to infinity)
- Req must be close to R1
- Req < R1 + Rvoltmeter
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E. Because this in parallel, it'll fry the meter
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Combinations of resistors can often be reduced to a single equivalent resistance through a step-by-step application of the ______ and _______ rules
State the Two special cases:
- series and parallel rules
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Detail Problem Solving approach for Circuit Problems
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Detail Problem Solving strategy for Kirchhoff's Rules
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Additionally, the ε = 9.0 V, find the current through R 3
check notes
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