All About Circuits

Basic Electricity

Series DC Circuits Practice Worksheet with Answers


27 questions By Tony R. Kuphaldt

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  • Question 13 of 27

    What would happen if three 6-volt light bulbs were connected as shown to a 6-volt battery? How would their brightnesses compare to just having a single 6-volt light bulb connected to a 6-volt battery?




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  • Question 14 of 27

    Qualitatively compare the voltage and current for each of the three light bulbs in this circuit (assume the three light bulbs are absolutely identical):




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  • Question 15 of 27

    Explain, step by step, how to calculate the amount of current (I) that will go through each resistor in this series circuit, and also the voltage (V) dropped by each resistor:




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  • B
    beelzebob May 17, 2020

    llaboutcircuits.com/worksheets/series-dc-circuits/. In question 5, total series resistance is sum of each resistor, not product. Correct both question and answer

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  • stefano.salari June 08, 2020

    Hello Everybody and thanks for your fantastic articles!

    I’m having troubles solving Excercise 19 of your Series circuits problems (https://www.allaboutcircuits.com/worksheets/series-dc-circuits/): For this excercise I’m getting a power dissipation for the heater of 403 W instead of 321.1 W.

    Since I’m learning electronics I’m surely doing something wrong… Here how I’m reasoning:

    1. With 110 V and a power dissipated of 500 W, I can calculate the current in the circuit, that should be I=P/V 500/110 = 4.545 A
    2. Knowing that the current in the circuit is 4.545 A I can use Ohm’s law to calculate the resistance of the heater: R=V/I 110/4.545 = 24 Ohm
    3. Now, longing the wires it’s the same as adding 6 Ohm of resistance, for a total resistance of 30 Ohm (24 + 6) so the current in the circuit will change accordingly. To find the new amount of current I use Ohm’s law once again: I=V/R 110/30 = 3.666 A
    4. Having a new current value of 3.666 A, I can now calculate power dissipation P=V*I 110*3.666 = 403 W

    Could you please help me understand where I’m wrong?

    Thank you so much!
    Stefano.

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    • RK37 June 09, 2020
      The mistake is in step 4. When you multiply source voltage by current, you are calculating the power dissipation of the entire circuit. Instead, you need to calculate the power dissipation of only the heater, i.e., the 24.2 Ω resistor. You can use P = (I^2)R for this. You know the current through the heater, so square the current and multiply it by the heater resistance: I = 110 V/30.2 Ω = 3.642 A; P = (3.642 A)(3.642 A)(24.2 Ω) = 321 W.
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