incandescent bulb power consumption

[Mike]

How can a 60W bulb only draw 60W of power if it's internal resistance is 19
ohms? Or does the resistance suddenly increase once the filament heats up?

Thanks.

 

[Terry Pinnell]

"Mike" <no_spam@comcast.net> wrote:

How can a 60W bulb only draw 60W of power if it's internal resistance is 19
ohms? Or does the resistance suddenly increase once the filament heats up?

Thanks.

Yes, considerably. In the UK, with about 235 V mains ac voltage, a 60W
bulb would have a hot resistance of about 1k.

--
Terry Pinnell
Hobbyist, West Sussex, UK

 

[Clarence]

"Mike" <no_spam@comcast.net> wrote in message
news:Aq-dna7phJHQDh_cRVn-uw@comcast.com...

How can a 60W bulb only draw 60W of power if it's internal resistance is 19
ohms? Or does the resistance suddenly increase once the filament heats up?

Thanks.

Oh yea! Typical 5/1, sometimes more.

 

[Mike]

Thanks. That makes perfect sense now...

"Clarence" <no@No.com> wrote in message
news:Z7xgd.2227$zx1.1121@newssvr13.news.prodigy.com...

"Mike" <no_spam@comcast.net> wrote in message
news:Aq-dna7phJHQDh_cRVn-uw@comcast.com...
How can a 60W bulb only draw 60W of power if it's internal resistance is
19
ohms? Or does the resistance suddenly increase once the filament heats
up?

Thanks.


Oh yea! Typical 5/1, sometimes more.

 

[R.Spinks]

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"Mike" <no_spam@comcast.net> wrote in message
news:Aq-dna7phJHQDh_cRVn-uw@comcast.com...

How can a 60W bulb only draw 60W of power if it's internal resistance is
19
ohms? Or does the resistance suddenly increase once the filament heats up?

Thanks.

 

[Joel Kolstad]

"Mike" <no_spam@comcast.net> wrote in message
news:_MSdnROmUPPqPR_cRVn-3Q@comcast.com...

Thanks. That makes perfect sense now...

Measuring the resistance of a light bulb is a common elementary circuits
class laboratory to get students thinking about resistance as not being
particularly fixed. It's very enlightening to many of them!

 

[Ken]

On Fri, 29 Oct 2004 23:51:38 -0400, "R.Spinks" <rspinks1@wowway.com>
wrote:

I believe this site should give you the information for which you are
looking. Cheers!


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[dB]

"Mike" <no_spam@comcast.net> wrote in message news:<Aq-dna7phJHQDh_cRVn-uw@comcast.com>...

How can a 60W bulb only draw 60W of power if it's internal resistance is 19
ohms? Or does the resistance suddenly increase once the filament heats up?

Thanks.

Your question has been answered in previous posts but for your
interest it is precisely that phenomena which is exploited when a
small filament bulb is used for amplitude control in a Wein bridge
oscillator.