Electric circuits maybe??

[iwfc87]

Hey, how's it going?

 

Ok..I've got this question that's popped out in this physics test and I don't know if it belongs in this category of the physics section of the forum. I've been getting mixed responses to this question and I just wanted to know what you all though. Here goes:

 

A heater is connected to 240V AC and is made up of 2 identical heating elements, with the same resistances. The heater has a switch that allows the heater to be swtiched on to a High Setting, a Medium Setting or Low Setting. This switch causes the 2 heating elements to be connected to the circuit differently.

 

Parallel, Series and only one element is heated.

 

Which circuit would be best for the high setting, which circuit eould be best for medium setting and which circuit would be best for low setting. Justify your answer.

 

There it was.

 

Thanks!

[atinymonkey]

Parallel for the high setting, as the 240v will be divided between the two elements.

 

Series would step down the V over the two elements, with the first element acting as a regulator by providing resistance for the second element, the inefficency of the curicut should reduce the Volts to heat ratio sufficently to be called the low setting.

 

One element all alone would be the medium power setting setting, as the 240v would be efficently transferred to the one element without resistance other than that in the element as it converts the energy to heat.

 

Probably. I'm guessing as I'm bored.

[Kedas]

The lower the resistance the higher the heat:

meaning:

series R+R = 2R

parallel R//R = R/2 (smallest resistence highest head)

P=U*U/R