There is a question in my textbook:

A current of $7\ \mathrm{A}$ goes through the heating element in a hair-drier. The voltage of the heating element is $240\ \mathrm{V}$.

b) How many joules of energy does each coulomb supply to the element as it goes through?

I understand this is a simple problem.

So it's 240 volts. Can this just be changed to 240 joules per coulomb? Is voltage and energy per unit charge related?

  • $\begingroup$ I fixed up some confusion between units and the quantities they measure in the edit I made. $\endgroup$ – David Z May 13 '17 at 3:46
  • $\begingroup$ Joules express energy, Coulombs charge, and Amps current (charge/second). Can you take it from here? $\endgroup$ – hdhondt May 13 '17 at 4:04
  • $\begingroup$ Two points differ in potential by one volt if the work done in taking one coulomb between those two points is one joule. $\endgroup$ – Farcher May 13 '17 at 5:29
  • $\begingroup$ You're absolutely correct $\endgroup$ – Ofek Gillon May 13 '17 at 8:16

$1$ J is the work done in taking 1 C between a potential difference of 1 V. Then, since the electric work is $qU$, $1\, J = 1\, C\cdot V$, or $1\,V = 1\,J/C$: you were right.


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