Answer:
(a) The current in amperes that flows through the toy's circuit is 0.923A
(b) The power supplied to the toy is 5.78721W
(c) The internal resistance r2 of the failed dry cell is 72Ω
Explanation:
From the circuit diagram attached. We have the electric component:
B1 = 3* 1.58 = 4.74V
B2 = 1.53V
r1 = 3*0.0205 = 0.0615Ω
r2 = 0.105Ω
R = 6.625Ω
Since the internal resistances and the resistor R are connected in series, we can calculate the total resistance RT as
RT = r1 + r2 +R = 0.0615 + 0.105 + 6.625
= 6.7915Ω
Total Voltage supplied to the circuit by both batteries V = B1 + B2 = 4.74 + 1.53 = 6.27V
(a) CIRCUIT CURRENT
The current I, flowing through the circuit is i =
= 
=0.923A
The current in amperes that flows through the toy's circuit is 0.923A
(b) THE POWER SUPPLIED TO THE TOY
Power P = I*V =0.923*6.27 = 5.78721W
The power supplied to the toy is 5.78721W
(c) THE VALUE OF r2
Due to dry cell failure, the power supplied to the toy is reduced to 0.5W
Now Power P = 
. To calculate the new total resistance of the circuit we will make R the subject of the formular
R=
= 
= 
= 78.6258Ω
Remember that RT = r1 + r2 + R
r1 =RT- (R +r2)
r1 = 78.6258 - 6.6865 =71.9393Ω
The internal resistance r2 of the failed dry cell is 72Ω
