Homework Help Forum: Physics

Posted by Kate on Wednesday, August 26, 2009 at 11:03pm.

I'm stumped on what formula to use for the following question. A 1.5V battery does 4.5*10^2 J of work in 120s. Calculate the current through the battery Calculate the number of elementary charges that pass through the battery. I've been trying to figure out the formula to start with and would really appreciate some help.

• Physics - DrBob222, Thursday, August 27, 2009 at 12:10am

  volts = joules/coulomb and coulomb = amp*sec so volts = joules/amp*sec.

  
  

• Physics - Kate, Thursday, August 27, 2009 at 12:18am

  So I solve for a=J/v*s to get the current (4.5*10^2/1.5*120). I hope I got this right and thanks very much.

  
  

• Physics - drwls, Thursday, August 27, 2009 at 1:56am

  Your formula will give you the number of Amperes of current. Divide that by the electron charge (1.6*10^-19 Coulombs) to get the rate that electrons pass through. Multiply that by 120s for the number of electrons.

  
  

• Physics - Kate, Thursday, August 27, 2009 at 1:12pm

  Thanks!

  
  

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