- #1

Laura555

- 1

- 0

From my understanding, transformers allow electricity to travel long distances with minimal energy loss because they initially use a step-up transformer which reduces the current (which reduces the heat loss and hence energy loss). However, I do not understand how a step-up transformer manages to create a high voltage and low current AND also has a low resistance (to minimise heat loss). From Ohm's law, the resistance of the primary circuit (in picture above) should be:

R=V/I= 6/0.1 = 60 Ohms

The resistance of the secondary circuit, however, should be:

R=V/I = 48/0.0125 = 3840 Ohms. [I know this must be incorrect, because it would make no sense as it would lead to massive heat loss!]

Obviously, the power is the same in both circuits, P=IV=0.6W.

My question is:

1. What is the resistance of the secondary (middle) circuit and why does Ohm's law not work here?

2. Also, if the type of wire used in all the circuits was the same, they should have identical resistances (if there are no appliances are in the circuits). So how could 48V (48J of energy per coulomb) produce such a low current - if the energy isn't moving the electrons to produce a high current or being wasted as heat to the surroundings, where is it going?

Many thanks for any help offered!