Finding power consumed by an electric razor

by kohlzie122
Tags: circuits, electricity, homework help, introphysics
kohlzie122 is offline
Feb8-09, 03:26 PM
P: 2
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?


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.
Phys.Org News Partner Science news on
Internet co-creator Cerf debunks 'myth' that US runs it
Astronomical forensics uncover planetary disks in Hubble archive
Solar-powered two-seat Sunseeker airplane has progress report
berkeman is offline
Feb8-09, 03:45 PM
berkeman's Avatar
P: 39,723
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...
kohlzie122 is offline
Feb8-09, 04:36 PM
P: 2
Oh man that was easy.. I'm a little embarrassed. Thanks for the help!

tigerwms is offline
Feb10-09, 09:16 PM
P: 1

Finding power consumed by an electric razor

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.

Register to reply

Related Discussions
Energy consumed to create force Classical Physics 8
power in / power out for electric motor Engineering Systems & Design 7
least fuel consumed from point A to B with no time constraint Mechanical Engineering 7
What would happen if I were to near and be consumed by a black hole? Astrophysics 1
100 Calories consumed/mile? General Physics 3