If a 4 Ω resistor, a 7 Ω resistor and a 12 Ω resistor are connected in parallel, which resistor has the most current in it?

4 Ω

7 Ω

12 Ω

They all have the same.

The formula for current in a resistor is

Current = (voltage) / (resistance)

You'll notice that Resistance is in the denominator of the fraction,

and that means that the current changes in the opposite direction

from the resistance. Smaller resistance means bigger current, and

bigger resistance means smaller current.

The resistors in your question are connected in parallel, so they

all have the same voltage across them. According to the simple

formula for current, then, the smallest resistor will have the biggest

current through it. That would be the 4-ohmer.