Finding power consumed by an electric razor

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Homework Help Overview

The discussion revolves around calculating the power consumed by an electric razor when used with a different voltage supply than it was designed for. The subject area includes electrical power, voltage, and resistance in the context of AC circuits.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to use the power formula P=IV and considers the implications of resistance remaining constant when switching from 120 V to 220 V. Another participant suggests writing separate equations for each voltage scenario to clarify the situation.

Discussion Status

The discussion is active, with participants exploring different approaches to the problem. Some guidance has been offered regarding the use of resistance and the formulation of equations, but there is no explicit consensus on the solution yet.

Contextual Notes

The original poster expresses uncertainty about how the constant resistance impacts the power calculation, indicating a potential gap in understanding the relationship between voltage, current, and resistance in this context.

kohlzie122
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A tourist takes his 21 W, 120 V AC razor to Europe, finds a special adapter, and plugs it into 220 V AC. What power does the razor consume as it goes up in smoke?


P=IV=deltaVsquared/R


attempt at solution:
I used P=IV for 120 V to find the current, and using that number, plugged the numbers into the equation for 220V. The hint for the problem says that the resistance doesn't change for the razor in Europe... but I don't know how that helps. I feel like I'm missing something very easy but I'm stuck.
 
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Welcome to the PF. The key here is that the resistance doesn't change. I don't think you want to write:

[tex]P = \frac{\Delta {V^2}}{R}[/tex]

Instead, write two equations, one for the US and one for smokey Europe...
 
Last edited:
Oh man that was easy.. I'm a little embarrassed. Thanks for the help!
 
Hey seems like you guys figured it out. Can you help me. I'm stuck on the same question and I don't know what to do.
 

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