Question

if the ristance is 2.25 what is the ristance percent

Answer 1

Correct option is

B

1.5 V

emf=I(R+r)−−−(a)

WhenI=0.5,R=2ohm

we know that, 

emf=V

Therefore Eq(a)become V=0.5(2+r)=>1/2(2+r)

2V=2+r−−−(1)

WhenI=0.25,R=5ohm

Therefore Eq(a)become

V=0.25(5+r)=>1/4(5+r)

4V=5+r−−−(2)

Subtract eq(1) from (2)

4V−2V=5+r−2−r

2V=3

V=3/2

V=1.5v

Hence, the option B is the correct answer.