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Resistor worksheet

Grades 10–11

Solve each problem and show your work. Round answers to 2 decimal places where needed.

  1. Problem 1.
    • Connection: Parallel
    • Resistor values (Ω): 140, 250, 400
    • Supply voltage (optional): 10 V

    Find: Total resistance (parallel)

  2. Problem 2.
    • Connection: Series
    • Resistor values (Ω): 100, 220, 470
    • Supply voltage (optional): 8 V

    Find: Total resistance (series)

  3. Problem 3.
    • Connection: Parallel
    • Resistor values (Ω): 100, 220, 470
    • Supply voltage (optional): 11 V

    Find: Total resistance (parallel)

  4. Problem 4.
    • Connection: Parallel
    • Resistor values (Ω): 120, 190, 375
    • Supply voltage (optional): 10 V

    Find: Total resistance (parallel)

  5. Problem 5.
    • Connection: Parallel
    • Resistor values (Ω): 100, 220, 470
    • Supply voltage (optional): 14 V

    Find: Total resistance (parallel)

  6. Problem 6.
    • Connection: Series
    • Resistor values (Ω): 140, 255, 575
    • Supply voltage (optional): 13 V

    Find: Total resistance (series)

  7. Problem 7.
    • Connection: Parallel
    • Resistor values (Ω): 100, 220, 450
    • Supply voltage (optional): 9 V

    Find: Total resistance (parallel)

  8. Problem 8.
    • Connection: Series
    • Resistor values (Ω): 100, 150, 425
    • Supply voltage (optional): 11 V

    Find: Total resistance (series)

  9. Problem 9.
    • Connection: Parallel
    • Resistor values (Ω): 100, 220, 470
    • Supply voltage (optional): 7 V

    Find: Total resistance (parallel)

  10. Problem 10.
    • Connection: Series
    • Resistor values (Ω): 100, 220, 470
    • Supply voltage (optional): 11 V

    Find: Total resistance (series)

Answer key: Resistor worksheet

  1. 1. Total resistance (parallel): 73.3 Ω

    1. In parallel, every resistor gets the same voltage. So add the reciprocals: 1 divided by each value

      1R=1140+1250+1400=0.0136428571 S
    2. Turn that sum back into a resistance by taking 1 divided by it. This is the total

      R=10.0136428571=73.2984293194 Ω
    3. Find the total current I from the supply with Ohm's law: the voltage V divided by the total resistance R

      I=1073.2984293194=0.1364285714 A
    4. Find the total power P: the voltage times the current

      P=10×0.1364285714=1.3642857143 W
    5. Each resistor gets the full supply voltage. So for the first one, R₁, divide the voltage by its resistance to get its current

      I₁=10140=0.0714285714 A
    6. Find the power (heat) in R₁: the voltage squared divided by its resistance

      P₁=102140=0.7142857143 W
  2. 2. Total resistance (series): 790 Ω

    1. In series, the same current passes through every resistor, so just add the resistances

      R=100+220+470=790 Ω
    2. Find the total current I from the supply with Ohm's law: the voltage V divided by the total resistance R

      I=8790=0.0101265823 A
    3. Find the total power P: the voltage times the current

      P=8×0.0101265823=0.0810126582 W
    4. Each resistor takes a share of the voltage that matches its resistance. For the first one, R₁, multiply the current by its resistance

      V₁=0.0101265823×100=1.0126582278 V
    5. Find the power (heat) in R₁: the current squared times its resistance

      P₁=0.01012658232×100=0.0102547669 W
  3. 3. Total resistance (parallel): 59.98 Ω

    1. In parallel, every resistor gets the same voltage. So add the reciprocals: 1 divided by each value

      1R=1100+1220+1470=0.0166731141 S
    2. Turn that sum back into a resistance by taking 1 divided by it. This is the total

      R=10.0166731141=59.9767981439 Ω
    3. Find the total current I from the supply with Ohm's law: the voltage V divided by the total resistance R

      I=1159.9767981439=0.1834042553 A
    4. Find the total power P: the voltage times the current

      P=11×0.1834042553=2.0174468085 W
    5. Each resistor gets the full supply voltage. So for the first one, R₁, divide the voltage by its resistance to get its current

      I₁=11100=0.11 A
    6. Find the power (heat) in R₁: the voltage squared divided by its resistance

      P₁=112100=1.21 W
  4. 4. Total resistance (parallel): 61.49 Ω

    1. In parallel, every resistor gets the same voltage. So add the reciprocals: 1 divided by each value

      1R=1120+1190+1375=0.0162631579 S
    2. Turn that sum back into a resistance by taking 1 divided by it. This is the total

      R=10.0162631579=61.4886731392 Ω
    3. Find the total current I from the supply with Ohm's law: the voltage V divided by the total resistance R

      I=1061.4886731392=0.1626315789 A
    4. Find the total power P: the voltage times the current

      P=10×0.1626315789=1.6263157895 W
    5. Each resistor gets the full supply voltage. So for the first one, R₁, divide the voltage by its resistance to get its current

      I₁=10120=0.0833333333 A
    6. Find the power (heat) in R₁: the voltage squared divided by its resistance

      P₁=102120=0.8333333333 W
  5. 5. Total resistance (parallel): 59.98 Ω

    1. In parallel, every resistor gets the same voltage. So add the reciprocals: 1 divided by each value

      1R=1100+1220+1470=0.0166731141 S
    2. Turn that sum back into a resistance by taking 1 divided by it. This is the total

      R=10.0166731141=59.9767981439 Ω
    3. Find the total current I from the supply with Ohm's law: the voltage V divided by the total resistance R

      I=1459.9767981439=0.2334235977 A
    4. Find the total power P: the voltage times the current

      P=14×0.2334235977=3.2679303675 W
    5. Each resistor gets the full supply voltage. So for the first one, R₁, divide the voltage by its resistance to get its current

      I₁=14100=0.14 A
    6. Find the power (heat) in R₁: the voltage squared divided by its resistance

      P₁=142100=1.96 W
  6. 6. Total resistance (series): 970 Ω

    1. In series, the same current passes through every resistor, so just add the resistances

      R=140+255+575=970 Ω
    2. Find the total current I from the supply with Ohm's law: the voltage V divided by the total resistance R

      I=13970=0.0134020619 A
    3. Find the total power P: the voltage times the current

      P=13×0.0134020619=0.1742268041 W
    4. Each resistor takes a share of the voltage that matches its resistance. For the first one, R₁, multiply the current by its resistance

      V₁=0.0134020619×140=1.8762886598 V
    5. Find the power (heat) in R₁: the current squared times its resistance

      P₁=0.01340206192×140=0.0251461367 W
  7. 7. Total resistance (parallel): 59.64 Ω

    1. In parallel, every resistor gets the same voltage. So add the reciprocals: 1 divided by each value

      1R=1100+1220+1450=0.0167676768 S
    2. Turn that sum back into a resistance by taking 1 divided by it. This is the total

      R=10.0167676768=59.6385542169 Ω
    3. Find the total current I from the supply with Ohm's law: the voltage V divided by the total resistance R

      I=959.6385542169=0.1509090909 A
    4. Find the total power P: the voltage times the current

      P=9×0.1509090909=1.3581818182 W
    5. Each resistor gets the full supply voltage. So for the first one, R₁, divide the voltage by its resistance to get its current

      I₁=9100=0.09 A
    6. Find the power (heat) in R₁: the voltage squared divided by its resistance

      P₁=92100=0.81 W
  8. 8. Total resistance (series): 675 Ω

    1. In series, the same current passes through every resistor, so just add the resistances

      R=100+150+425=675 Ω
    2. Find the total current I from the supply with Ohm's law: the voltage V divided by the total resistance R

      I=11675=0.0162962963 A
    3. Find the total power P: the voltage times the current

      P=11×0.0162962963=0.1792592593 W
    4. Each resistor takes a share of the voltage that matches its resistance. For the first one, R₁, multiply the current by its resistance

      V₁=0.0162962963×100=1.6296296296 V
    5. Find the power (heat) in R₁: the current squared times its resistance

      P₁=0.01629629632×100=0.0265569273 W
  9. 9. Total resistance (parallel): 59.98 Ω

    1. In parallel, every resistor gets the same voltage. So add the reciprocals: 1 divided by each value

      1R=1100+1220+1470=0.0166731141 S
    2. Turn that sum back into a resistance by taking 1 divided by it. This is the total

      R=10.0166731141=59.9767981439 Ω
    3. Find the total current I from the supply with Ohm's law: the voltage V divided by the total resistance R

      I=759.9767981439=0.1167117988 A
    4. Find the total power P: the voltage times the current

      P=7×0.1167117988=0.8169825919 W
    5. Each resistor gets the full supply voltage. So for the first one, R₁, divide the voltage by its resistance to get its current

      I₁=7100=0.07 A
    6. Find the power (heat) in R₁: the voltage squared divided by its resistance

      P₁=72100=0.49 W
  10. 10. Total resistance (series): 790 Ω

    1. In series, the same current passes through every resistor, so just add the resistances

      R=100+220+470=790 Ω
    2. Find the total current I from the supply with Ohm's law: the voltage V divided by the total resistance R

      I=11790=0.0139240506 A
    3. Find the total power P: the voltage times the current

      P=11×0.0139240506=0.153164557 W
    4. Each resistor takes a share of the voltage that matches its resistance. For the first one, R₁, multiply the current by its resistance

      V₁=0.0139240506×100=1.3924050633 V
    5. Find the power (heat) in R₁: the current squared times its resistance

      P₁=0.01392405062×100=0.0193879186 W