Abattery has an emf of 15.0 v. the terminal voltage of the battery is 12.2 v when it is delivering 26.0 w of power to an external load resistor r. (a) what is the value of r? ω (b) what is the internal resistance of the battery?

(a) 5.725 Ω

(b) 1.3 Ω

Explanation:

(a)

E = emf of the battery = 15.0 Volts

V = terminal voltage of the battery = 12.2 Volts

P = Power delivered to external load resistor "R"  = 26.0 W

R = resistance of external load resistor

Power delivered to external load resistor is given as

26.0 = 12.2²/R

R = 5.725 Ω

(b)

r = internal resistance of the battery

i = current coming from the battery

Power delivered to external load resistor is given as

P = i V

26.0 = i (12.2)

i = 2.13 A

Terminal voltage is given as

V = E - ir

12.2 = 15 - (2.13) r

r = 1.3 Ω

b.

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