Calculating Resistance: 3 & 12 Ohm Resistors for 2.4 Ohm Result

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The smallest resistance obtainable using a 3-ohm and a 12-ohm resistor is 2.4 ohms when the resistors are connected in parallel. The formula for calculating the total resistance in parallel is 1/R_total = 1/R1 + 1/R2. Applying this formula, 1/R_total = 1/3 + 1/12 results in an effective resistance of 2.4 ohms. In contrast, connecting the resistors in series yields a total resistance of 15 ohms. Understanding the configuration of resistors is crucial for accurate resistance calculations.
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what is the smallest resistance that can be obtained by using onlu a 3 ohm resistor and a 12 ohm resistor??

can anyone please tell me why the answer is 2.4ohm?

i calculATED USING 1/3 = 1/2 AND I GOT 4 OHMS:mad:

thx anyway
 
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Okay, if the resistors are placed in series the effective resistance of the system is simply the sum of the individual resistances (i.e. R_{t}=3+12=15\Omega).

However, if we place the resitors are placed in parallel the effective resistance of the array is...?
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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