When three equal resistors are connected in series across an emf source, the total resistance in the circuit is simply three times the resistance of one resistor. Let's denote the resistance of one resistor as "R."

So, in the series configuration, the total resistance (R_total) is 3R.

The power dissipated in the series circuit can be calculated using the formula:

P = (V² / R_total)

Given that the power dissipated is 9 W and the total resistance is 3R, we can write:

9 W = (V² / 3R)

Now, let's consider what happens when the same three resistors are connected in parallel. In a parallel configuration, the reciprocal of the total resistance (1 / R_parallel) is the sum of the reciprocals of the individual resistances (1 / R):

1 / R_parallel = 1 / R + 1 / R + 1 / R 1 / R_parallel = 3 / R

Now, let's find the total resistance for the parallel configuration:

R_parallel = R / 3

Now, we can calculate the power dissipated in the parallel configuration:

P_parallel = (V² / R_parallel) P_parallel = (V² / (R / 3)) P_parallel = 3 * (V² / R)

Since we know the power dissipated in the series configuration (P) is 9 W, the power dissipated in the parallel configuration (P_parallel) is:

P_parallel = 9 * P_parallel = 9 * 9 W= 81 W

So, when the same resistors are connected in parallel across the same source, the power dissipated is 27 W.

The correct answer is option 3: "81W."