Download Circuit Test Mini-Review

Circuit Test Mini-Review
For the following circuit:
20 Ω
120 V
50 Ω
Circuit 1 Questions
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Is it series or parallel?
What is the total resistance?
What is the total current?
What is the current through the 20 Ω
resistor?
• How much power is dissipated by both
resistors?
Label the following
What do you need to know?
In a basic circuit (one battery, one resistor)
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To calculate Power?
To figure out Resistance?
To calculate Voltage?
To find electric current?
For the following circuit:
Circuit 2 Questions
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Is it series or parallel?
What is the total voltage?
What is the voltage in each branch?
What is the current in branch 1?
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“ in branch 2?
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“ in branch 3?
What is the total current?
What is the total resistance?
In your home…
• Are your plugs hooked up in series, or
parallel?
• What device prevents your current from
getting too high?
• If a lightbulb has a Power of 40 Watts, what is
the resistance? (voltage in each plug is 120V)
Answers Slide 1
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Series (only has one path)
70 Ohms (add up resistors in series)
1.7 Amps (I = V/R)
1.7 Amps (current is the same everywhere in
the same path – constant in series)
• 205 W (Power = V*I)
Answers Slide 2
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A. Resistor
B. Switch
C. Bulb
D. Battery
Answers Slide 3
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P=V*I
R=V/I
V= I * R
I=V/R
Answers Slide 4
• Parallel (multiple paths)
• 9V
• 9V (voltage is the same at each branch in
parallel)
• 4.5 Amps, 3 Amps, 9 Amps, (I = V/R)
• I = 16.5 Amps (Add up all branch currents to
find total current)
• R = .55 Ohms (R = V/I or 1/R = ½+1/3+1/1)
Answers Slide 5
• Parallel (if you unplug one thing, everything
else stays on. Constant voltage at each plug)
• Circuit Breaker (or Fusebox)
• 364 Ohms (P = V*I, R = V/ I)
so
• 40 = 120 * I
• I = .33 Amps
• R = 120/.33 = 364 Ohms