JEE MAIN - Physics (2019 - 8th April Morning Slot - No. 15)
For the circuit shown, with R1 = 1.0W, R2 = 2.0 W,
E1 = 2 V and E2 = E3 = 4 V, the potential
difference between the points 'a' and 'b' is
approximately (in V):
_8th_April_Morning_Slot_en_15_1.png)
3.3
2.7
2.3
3.7
Explanation
Given circuit is
_8th_April_Morning_Slot_en_15_2.png)
Above circuit can be viewed as
_8th_April_Morning_Slot_en_15_3.png)
This is a parallel combination of three cells or in other words, a parallel grouping of three cells with internal resistances.
So, $${V_{ab}} = {E_{eq}} = {{{I_{eq}}} \over {{r_{eq}}}} = {{{{{E_1}} \over {{r_1}}} + {{{E_2}} \over {{r_2}}} + {{{E_3}} \over {{r_3}}}} \over {{1 \over {{r_1}}} + {1 \over {{r_2}}} + {1 \over {{r_3}}}}}$$
$$ = {{{2 \over 2} + {4 \over 2} + {4 \over 2}} \over {{1 \over 2} + {1 \over 2} + {1 \over 2}}} = {{10} \over 3}V \approx 3.3\,V$$
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