Question

When a 3 ohm resistance coil is connected across the terminals of a battery the current is 1.5


a. when a 5 ohm resistance is connected across the same battery current is 1


a. find the internal resistance?

Answer 1

Let the internal resistance be r
R1 = 3 ohm
E = I(r + R1) = 1.5 x (r + 3 ) = 1.5r + 4.5  .................eq1  

R2 = 5 ohm 
E = I(r + R2)  = 1 x(r + 5) = r +5 ....................eq 2 

from eq 1 and 2 
1.5r + 4.5 = r + 5 
⇒ 1.5r - r = 5 - 4.5 = 0.5 
⇒ 0.5 r   = 0.5 
⇒r = 1 ohm 

hope , it may  help you 

Answer 2

Answer:

Explanation:

Let the internal resistance be r

R1 = 3 ohm

E = I(r + R1) = 1.5 x (r + 3 ) = 1.5r + 4.5  .................eq1  

R2 = 5 ohm 

E = I(r + R2)  = 1 x(r + 5) = r +5 ....................eq 2 

from eq 1 and 2 

1.5r + 4.5 = r + 5 

⇒ 1.5r - r = 5 - 4.5 = 0.5 

⇒ 0.5 r   = 0.5 

⇒r = 1 ohm