A current of \(1\ ampere\) flows in a series circuit containing an electric lamp and a conductor of \(10\ \Omega\)  when connected to a \(20\ V\) battery. Calculate the resistance of the electric lamp. Now if a resistance of \(15\)  is connected in parallel with this series combination, what change (if any) in current flowing through \(10\ \Omega\)  conductor? Give reason.
 
Let \(R_{1}\) be the resistance of electric lamp. Then, the total resistance is
 
R=ii+i
 
By Ohm's law , we get the value \(R_1\) as   \(\Omega\).
 
The resistance of the lamp is connected in series, then \(R\) \(=\) 20 \(\Omega\) .
 
Then, If it is connected with \(15\ \Omega\) resistance in parallel, R=iΩ
 
The value of current is given by the formula
 
I=ii
 
On substituting the known values, we get, the current is \(A\)
 
Important!
Note: Enter your answers with two decimal digits.