The (.) means a closed key= closed circuit. THe current is flowing.
I have done this:
1/R= 1/6+1/3= 3/6= 1/2 (the 6 ohm and 3 ohm resistors are in ||)
R= 2 ohms
Now:
(2+10) ohms= 12 ohms (They are now in series)
Acc. to Ohm's law:
I= V/R
= 12/12
= 1 Ampere
Now I have found the total current in the circuit.
But I need to find the current through the 3 ohm resistor. I can't do it. Please help me find the current through the 3 ohm resistor.
You have 1 amp across the 3-ohm/6-ohm pair. You know the resistance of that pair, so you can compute the voltage drop across it.
Then you will know the voltage across the 3-ohm.