Step-by-step explanation:
Here two internal resistances are in parallel so equivalent internal resistance r 
eq
 
 =1∣∣1= 
1+1
1×1
 
 =1/2=0.5Ω
According to maximum power theorem the power will be max when internal resistance is equal to external resistance. since, r 
eq
 
 =R=0.5Ω
Maximum current through R is I 
max
 
 = 
r 
eq
 
 +R
V
 
 = 
0.5+0.5
2
 
 =2A
Maximum power is P 
max
 
 =I 
max
2
 
 R=2 
2
 ×0.5=2W
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