Why circuit components behave differently · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Why circuit components behave differently

Science · Energy · ages 10-11
Name ______________________   Date ____________

  1. True or false: adding a second bulb to a series circuit, using the same battery, makes each bulb burn brighter.

    Circle one:   True   False

  2. A circuit with one bulb and a circuit with two bulbs in series both use the same battery. Which bulb glows dimmer?

    • The single bulb on its own
    • Each bulb in the two-bulb circuit
    • They are exactly the same brightness

  3. Circuit A has 1 buzzer. Circuit B has 2 buzzers wired in series. Both use an identical battery. Which is true?

    • Circuit A's buzzer is louder than each buzzer in Circuit B
    • Each buzzer in Circuit B is louder than Circuit A's buzzer
    • Both circuits sound exactly the same

  4. A series circuit has 3 bulbs and one switch. What happens to all 3 bulbs when you open the switch?

    • All 3 turn off at the same time
    • Only the bulb closest to the switch turns off
    • They get dimmer but stay lit

  5. Look at the chart comparing brightness in two circuits that use the same battery. Why is each bulb in Circuit B dimmer?

    Circuit A:1 bulb10Circuit B:2 bulbs5
    • Circuit B's battery is weaker
    • The two bulbs in Circuit B share the same energy that one bulb would get in Circuit A
    • Circuit B's wires are longer

  6. A single buzzer connected to a battery makes 10 units of noise. Two identical buzzers wired in series share that same energy equally. How many noise units does each buzzer make?

    Answer: ______________

  7. Circuit A has 1 bulb and 1 switch. Circuit B has 4 bulbs and 1 switch. Both use the same battery. Which statement is true?

    • Circuit B's switch behaves differently because it has more bulbs
    • Each bulb in Circuit B is brighter than Circuit A's bulb
    • Circuit A's bulb is brighter, but both switches still turn everything off completely when opened

  8. Jack says, 'If I keep adding bulbs to my series circuit, eventually the switch won't be able to turn them all off at once.' What is wrong with his idea?

    • He's right, more bulbs need more switches
    • He's wrong: one switch on a single loop always turns off every bulb together, no matter how many there are
    • He's wrong: adding bulbs switches itself off automatically
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Why circuit components behave differently W1-mt_-QY08-88rw-s1

  1. False · The battery's energy now has to stretch across two bulbs, so each one actually gets dimmer, not brighter.
  2. Each bulb in the two-bulb circuit · Two bulbs must share the same energy from one battery, so each one gets less than the single bulb does.
  3. Circuit A's buzzer is louder than each buzzer in Circuit B · Circuit B's two buzzers must share the same energy, so each one sounds quieter than Circuit A's single buzzer.
  4. All 3 turn off at the same time · A series circuit has just one path for energy, so opening the switch stops it for every bulb at once.
  5. The two bulbs in Circuit B share the same energy that one bulb would get in Circuit A · Same battery, more bulbs: the energy splits between them, so each bulb in Circuit B gets a smaller share.
  6. 5 · The total energy is shared equally between the two buzzers: 10 divided by 2 is 5.
  7. Circuit A's bulb is brighter, but both switches still turn everything off completely when opened · More bulbs share energy and lower brightness, but a switch on a single loop always turns everything off together, no matter how many bulbs are on it.
  8. He's wrong: one switch on a single loop always turns off every bulb together, no matter how many there are · A series circuit only has one path, so a single switch always controls everything on that path at once.
Worksheet · LightMySky