A rechargeable battery has "emf_{\u03b5battery}""=14.0V", internal resistance "r=4.00\\Omega" and battery capacity (total charge) "2.00 Ah".
When the battery is fully charged, a light bulb is connected to it for 8 hours (see picture above). The light bulb has specs "14.00V" and "1.00W". We assume the light bulb has constant resistance (independent of the current) and the emf of the battery remains constant.
After these 8 hours the battery is disconnected from the light bulb and connected in this circuit for charging:
The charger consists of a ideal voltage source with "emf_\u03b5=20.0 V" (with no internal resistance) and a resistor "R_1" in series.
(a) What is the minimum time that is needed to fully recharge the battery (with "R_1=0\\Omega")
(b) What should the resistance "R_1" be to fully recharge the battery in exactly 1 hour?
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