Two lightbulbs are each connected to a voltage of 120 V. One has a power of 25 W, the other 100 W. (a) Which lightbulb has the higher resist

Question

Two lightbulbs are each connected to a voltage of 120 V. One has a power of 25 W, the other 100 W. (a) Which lightbulb has the higher resistance? (b) Which lightbulb carries more current?

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Thiên Hương 5 years 2021-07-26T03:28:11+00:00 1 Answers 58 views 1

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  1. mocmien2
    0
    2021-07-26T03:29:49+00:00
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    Answer:

    (a) The 25 W bulb

    (b) The 100 W bulb

    Explanation:

    (a)

    Using,

    P = V²/R……………. Equation 1

    Where P = Power, V = Voltage, R = resistance.

    make R the subject of the equation

    R = V²/P………………. Equation 2

    For the 25 W bulb,

    Given: P = 25 W, V = 120 V

    Substitute into equation 2

    R = 120²/25

    R = 576 Ω

    For the 100 W bulb,

    Given: P = 100 W, V = 120 V

    Substitute into equation 2

    R = 120²/100

    R = 14400/100

    R = 144 Ω

    Hence the the 25 W bulb has the highest resistance.

    (b)

    Using,

    P = VI……………… Equation 3,

    Where I = current

    Make I the subject of the equation

    I = P/V………….. Equation 4

    For the 25 W bulb,

    Given: P = 25 W, V = 120 V

    Substitute into equation 4

    I = 25/120

    I = 0.208 A.

    For the 100 W bulb,

    Given: P = 100 W, V = 120 V

    Substitute into equation 4

    I = 100/120

    I = 0.833 A.

    Hence the 100 W bulb carries more current.

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