A cell of internal resistance r supplies curren... - JAMB Physics 2001 Question

Efficiency = power out put/power input * 100/1

= power out put/ power + that due * 100/1

to internal resistance

=> 75/1 = 1²R *100/1

        1<sup>2</sup>(R+r)<br />

i.e 75/100 = 6/6+r => 75 (6+r) = 100/*6

i.e 450 + 75r = 600

75r =600 - 450

i.e r = 150/75 = 2Ω

i.e r = 2Ω