Resistance of a light bulb question

In summary, the resistance of a light bulb using 75.0 W with a maximum voltage of 190 V and connected to a 60.0 Hz power source is calculated using the formula R = V^2/P. For a 120 W bulb, the same formula can be applied. The 60 Hz should be multiplied by 2pi and the relationship between peak and RMS voltage and current should be understood. The link provided can be useful for further understanding.
  • #1
Pepsi24chevy
65
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Hey guys I am having some trouble with this simple questions:
What is the resistance of a light bulb that uses an average power of 75.0 W when connected to a 60.0 Hz power source having a maximum voltage of 190 V?


(b) What is the resistance of a 120 W bulb?

I tried doing it by (75/190)^2 * (2pi60) but this is not correct.
 
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  • #2
One has to apply the equivalent of P = V I = V2/R = I2R for AC, so R = V2/P.

Since it is pure resistance, i.e. no reactance, the voltage and current are in phase.

Think of average and maximum.
 
  • #3
Ok, do i still have to multiply the 60hz by 2pi? Also, how do i handle it being connected to the power source?
 
  • #5
no but thanks for the link. I think that should of helped me get an idea
 

Related to Resistance of a light bulb question

What is resistance?

Resistance is the measure of how much a material or circuit impedes the flow of electric current. It is measured in ohms (Ω) and is represented by the symbol R.

How does resistance affect a light bulb?

The resistance of a light bulb determines how much current flows through it. A higher resistance means less current, resulting in a dimmer light. Conversely, a lower resistance means more current, resulting in a brighter light.

What factors affect the resistance of a light bulb?

The resistance of a light bulb is affected by its material, length, and thickness. Other factors include the temperature of the bulb and the voltage applied to it.

What is the formula for calculating resistance?

The formula for calculating resistance is R = V/I, where R is resistance in ohms, V is voltage in volts, and I is current in amperes.

How can I decrease the resistance of a light bulb?

To decrease the resistance of a light bulb, you can increase the voltage or decrease the length or thickness of the filament. However, be cautious as this can also cause the bulb to burn out more quickly.

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