[Physics] Why is high voltage dangerous

Question

High $V$ low $A$ electricity is transformed into low $V$ high $A$ through a step down transformer for safer use in homes.

But how is it any safer? The wattage is the same for the pre-transformer charge flow, and the post-transformer charge flow. The energy both charge flows transfer is also the same.

Edit: by safety I’m referring to human contact

Answer 1

You are confused with the same wattage, supposing that wattage is determined by pre-transformed $V_1$ and $A_1$.

But the order of things is other:

• $V_1$ is changed to $V_2$,
• then some resistor (a human body) is connected to the secondary, low voltage ($V_2)$ circuit,
• and the impedance of that resistor determines (by Ohm law) the $A_2$ (and - consequently - the wattage $V_2\cdot A_2$, too).

Only after determining $A_2$ is determined $A_1$, too, to fullfil the equation $A_2/A_1 = V_1/V_2.$
Symbolically:

$$V_1 \implies V_2\\ V_2/ R \implies A_2\\ A_2 \implies A_1$$