The discussion revolves around determining the internal series resistance of a battery connected to resistors of different values. The original poster presents a scenario where a battery is connected to a 4 ohm resistor and then to a 9 ohm resistor, noting that the heat released in both cases is the same.
There is an ongoing exploration of the relationship between power, load resistance, and internal resistance. Some participants have offered hints and guidance on how to approach the problem mathematically, while others are clarifying misconceptions about the behavior of power in relation to resistance.
Participants are working within the constraints of the problem as presented, including the requirement that the heat released is the same for both resistor configurations. There is a focus on understanding the implications of the assumptions made regarding current and resistance.
Can you give me a hint to find it correctly? From which formula should I start?PietKuip said:Your assumption that the currents (I1 and I2) are equal is not correct.
The power delivered to the load is maximal when the load resistor is equal to the internal resistance, so without calculation one can say that it is between 4 ohm and 9 ohm.
That is not correct: the power is zero at zero resistance (short circuit) and infinite resistance (open circuit).cnh1995 said:If you sketch the graph of power vs resistance, you'll see it is symmetrical on both the sides of the peak power.
r=6 ohm Thank you!cnh1995 said:If you want to go mathematically,
P=I2R will be helpful. Make proper substitution for I in terms of E and r.