Splung.com Physics Forum Forum Index Splung.com Physics Forum
Discuss physics or ask questions. Part of the Splung.com physics web site.
 
   SearchSearch   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Current and Heat

 
Post new topic   Reply to topic    Splung.com Physics Forum Forum Index -> Physics Help. Ask a Physics Expert
View previous topic :: View next topic  
Author Message
JArcadia7



Joined: 04 Mar 2015
Posts: 1
Location: Pennsylvania

PostPosted: Fri Mar 06, 2015 1:53 am    Post subject: Current and Heat Reply with quote

Some stoves use the heat produced by current flowing through a conductor. If the heating element (conductor) has a resistance of 30 ohms, how long will the burner have to work to heat 500 g of 30C water up to its boiling point? The specific heat of water is 4.19 x 103 J/kgC, and the household voltage is (120V).

How do I solve this? Which formula's do I have to use?
Back to top
View user's profile Send private message
hepcj
Site Admin


Joined: 23 Jun 2007
Posts: 125

PostPosted: Tue Mar 10, 2015 2:08 am    Post subject: Reply with quote

To solve this you need to find the energy required to heat the mass of water to 100 deg, from 30 deg.
$$E= mc\delta\theta$$

The power of the heater is the amount of energy it can produce in one second and this is given by \(P= I^2 R\). But you don't have the current, so you use Ohm's law V=IR to substitute for I.

So the power will be \(V^2/R\)
To find how long it takes, divide the energy required by the power.
Back to top
View user's profile Send private message Send e-mail
Display posts from previous:   
Post new topic   Reply to topic    Splung.com Physics Forum Forum Index -> Physics Help. Ask a Physics Expert All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


© Copyright 2010 Splung.com