With 0.45 amp flowing through an 18-ohm resistor, the voltage across it is
V = I R = (0.45) x (18) = <em>8.1 volts .</em>
"But I asked for the battery voltage! That's the voltage across the resistor."
The ends of the resistor are connected directly to the battery terminals.
They're the same voltage.
"But what about the 6-ohm resistor ? Where does that figure in ?"
In parallel, it doesn't. It's also connected directly across the battery,
and it has its own current.
In parallel, neither resistor knows or cares whether or not there are
any other resistors present. In parallel, it makes no dif.
-- Before Adrian left the airplane, his gravitational potential energy was
(mass) x (gravity) x (height) = (80kg) x (9.81m/s²) x (1,000m) = 784,800 joules
-- When he reached the ground, his kinetic energy was
(1/2) x (mass) x (speed)² = (40kg) x (5m/s)² = 1,000 joules
-- Between the airplane and the ground, the Adrian lost
(784,800 joules) - (1,000 joules) = 783,800 joules
Where did all that energy go ?
Energy never just disappears. If it's missing, it had to go somewhere.
The Adrian used 783,800 joules of energy to push air our of his way
so that he could continue his parachute jump, and reach the ground
in time to be home for dinner.
