# Calculate Power Dissipated by a Lightbulb Socket

• BuBbLeS01
In summary, when a lightbulb is attached to a socket with corroded contacts, the actual power that is dissipated by the bulb is less than what is stated on the package. The lightbulb uses 117 watts instead of the stated 126 watts.
BuBbLeS01

## Homework Statement

The corroded contacts in a lightbulb socket have 8 Ω total resistance.How much actual power is dissipated by a 126 W (115 V) lightbulb screwed into the socket?

P = I*V
I = E/R

## The Attempt at a Solution

I = 115/8 = 14.375
I don't know how to calculate power...

Calculating Power

Electric Power in Watts is defined as Volts x Current

for example A device connected to a 12Volt DC source is measured to Draw 6 Amperes of current what is the Power Consumption of this Device Ans P = V x I = 12V x 6 A = 72 Watts

of Course algebraic substiutions from Ohms Lawcan lead to differnt forms such as

P = V x I I = V/R Therefore P = VxV/R

Or V = I x R so P = V x I = IxRxI = IxIxR

Yea I saw that there's like 3 different equations you can use but I had tried them all and none of them are getting the right answer...
P = V/I = V^2/R = I^2 * R
I =126/115 = 1.096 A
R = 8 Ohms
V = 115 V

V/I = 104.96
V^2/R = 1653.125
I^2 * R = 9.6

Why am I getting a different for all of them? I thought they were all equal??

You had to add the 8 Ohms Resistance as another load. Think about it, if they tell you the bulb is rated at 126 W at 115 V then I would = 126/115 = 1.1 Amps. This implies that Internal resistance of Bulb is 115V/1.1A = 105 Ohms. So Total resistanceis way more than 8ohms it is actually 8 + 105 = 113 ohms. the 8ohms is the resistance of the corrosion only. SO... Total Power = VxV/R = 115x115/113= 117 Watts. The resistance due to corrosion ACTUALLY causes the light bulb to use less power OF COURSE this means the Bulb will provide less light. This is exactly how a dimmer switch works

Oh I see...so I have to subtract the power lost due to the corrosion right? And I would use the I^2 * R = 9.6 W. 117 W - 9.6 W =107.5 W
Is that right?

Yes, That is a another very good way to think of it you attached another load in series (the corrosion) so there is leass power available to the light bulb both ways should yield same answer good luck

except you have to subtract the 9.6 watts ( this is the power consumed by the 8 ohms of corrosion) from the original 126 watts 126 - 9.6 ~ 117 Watts.

BTW Please tell me how you are able to type symbols (such as ohm sign) into your posts?

mikecal1 said:
BTW Please tell me how you are able to type symbols (such as ohm sign) into your posts?
Actually I don't know how to I copied and pasted the problem

Why do I subtract it from 126 and not the 117??

## 1. How do you calculate the power dissipated by a lightbulb socket?

To calculate the power dissipated by a lightbulb socket, you need to know the voltage and current of the lightbulb. The power can be calculated using the formula P = V x I, where P is power (in watts), V is voltage (in volts), and I is current (in amps).

## 2. What is the difference between power dissipated and power consumed?

Power dissipated refers to the amount of energy that is converted into heat or other forms of energy, while power consumed refers to the amount of energy that is used by the device. In the case of a lightbulb, the power dissipated is the heat energy that is produced by the light, while the power consumed is the electrical energy that is used to produce the light.

## 3. How does the power dissipated by a lightbulb socket affect its lifespan?

The power dissipated by a lightbulb socket can affect its lifespan because the more power is dissipated, the more heat is generated. This heat can cause the lightbulb to burn out faster as it puts more strain on its components. Therefore, it is important to choose the right wattage for a lightbulb to ensure it does not dissipate too much power.

## 4. Can the power dissipated by a lightbulb socket be reduced?

The power dissipated by a lightbulb socket can be reduced by using energy-efficient lightbulbs, such as LED or CFL bulbs. These types of bulbs use less power and produce less heat compared to traditional incandescent bulbs. It is also important to turn off lights when they are not in use to reduce power dissipation and save energy.

## 5. How does the power dissipated by a lightbulb socket affect energy consumption?

The power dissipated by a lightbulb socket directly affects energy consumption because the more power is dissipated, the more energy is being used. This means that using lightbulbs with higher wattage will result in higher energy consumption. Therefore, choosing lightbulbs with lower wattage and turning off lights when not in use can help reduce energy consumption and save on electricity bills.

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