Four cells each of internal resistance 1 ohm and e.m.f. 1.9v are connected to a external resistance of 18 ohm.the cells are connected in pair of two. the two pairs are connected in parallel . find the terminal potential difference of this combination?

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Answer 1 · 2017-08-24T15:06:10

The potential difference is $= 3.69 V$ $=3.69V$

We apply the equation

$U = R I$ $U=RI$

$E - U = r I$ $E-U=rI$

$E = (R + r) I$ $E=(R+r)I$

The emf is $E = 2 \cdot 1.9 = 3.8 V$ $E=2*1.9=3.8V$

The cells are in series-parallel and the internal resistances as well.

The total resistance is

$r+R=(1/2+1/2)+18=19Omega$

The current is

$I=3.9/19=0.21A$

So, the potential difference is

$=U=18*0.21=3.69V$