I am confused on how to apply the formula
If I am given a bulb say with power 60W and it is connected to a supply of 120V. Then the resistance of the bulb is 240$\Omega$ but if the bulb is connected to a resistor say 10 $\Omega$ in series then will the value of V to be put in the formula still be 120V ? And hence the resistance of bulb remain same? Or do we have to apply V'=V-I×10 (where I is the current in the circuit)to get net potential across the bulb ?
In a nutshell what is the V stand for in the formula - The supply voltage or the the potential drop across the bulb and why ?
P.S- This question came to my mind while solving this Question