Question

One electric bulb is rated 60W - 240 V and other 40 W-240V. Which bulb has a higher resistance and how many times?​

Answer 1

Answer:

Answer: The higher resistance is r_{2} and r_{2} is 1.6 times of r_{1}

Explanation:

Given that,

Power of first bulb P_{1} = 40 W

Voltage of first bulb V_{1} = 240 V

Power of second bulb P_{2}=25 W

Voltage of second bulb V_{2} = 240 V

We know that,

The power is the product of the voltage and current.

P = VI

Now, the resistance of first bulb

R_{1} = \dfrac{V^{2}}{P}

R_{1} =\dfrac{240\times 240}{40}

R_{1} = 1440 ohm

The resistance of the second power

R_{2} = \dfrac{240\times240}{25}

R_{2} = 2304 ohm

Therefore,

R_{2}>R_{1}

\dfrac{R_{2}}{R_{1}} = \dfrac{2304}{1440}

\dfrac{R_{2}}{R_{1}} = 1.6

R_{2} = 1.6 R_{1}

Hence, the higher resistance is r_{2} and r_{2} is 1.6 times higher then r_{1}