I am new here, this is more of a conceptual confirmation than mathemab

  • Thread starter Thread starter ALLIRIX
  • Start date Start date
  • Tags Tags
    Conceptual
AI Thread Summary
When a wire resists electrical current, it generates heat energy, but the efficiency of this conversion can vary. In a circuit with a power input of 20 watts, not all of this energy is converted to heat due to energy losses, as described by the formula P=I^2R. The movement of electrons in a circuit is slower than expected, and it is actually electromagnetic waves that transfer electricity. An experiment showed that while the electrical power was measured at 30 watts, the heating power calculated was only 20 watts, indicating potential inefficiencies. This suggests that not all electrical energy is converted to heat, with some energy remaining in the system.
ALLIRIX
Messages
4
Reaction score
0
When a wire resists an electrical current it produces heat energy. But how efficient is this transfer? If the electrical Power is 20watts is the heating power 20watts? (ignoring all other inefficiencies, just the conversion from Electrical to Heat)

I'm thinking since a circuit requires electrons to complete the circuit in order to have a current, the Powers won't be equal because some energy will remain within the electrons to keep them in movement.
 
Physics news on Phys.org
The power loss is given by the formula: ##P=I^2R##. Is this what you are looking for?
 
The electrons in the circuit don't quite work in the way that your intuition would expect, they don't move very fast at all in a circuit. It is actually an electromagnetic wave inside a wire that transfers "electricity".
 
I should probably explain further, I've done a school experiment converting electrical energy to heat. P=VI was used to find the electric power going through the Ohmic heating coil, and got an answer of 30 watts. It was used to heat 0.2kg of water and the equation Q/t = m×c×T/t was used to find the Heating Power which gave an answer of 20 watts. I was wondering if the lower answer is only due to inefficiencies of the experiment or that not 100% of the power is converted and some remains in the heating element as electrical energy.
 
Last edited:
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top