Here are the solutions for the circuit problem:
1) Current through 3Ω:
Step 1: Identify the series combination.
The 3Ω and 5Ω resistors are connected in series. Their equivalent resistance is:
Rseries=3Ω+5Ω=8Ω
Step 2: Determine the voltage across the series combination.
The 8Ω series combination is in parallel with the 2Ω resistor, and this entire parallel arrangement is connected directly across the 6.0V battery. Therefore, the voltage across the 8Ω series combination is 6.0V.
Step 3: Calculate the current through the 3Ω resistor.
Since the 3Ω resistor is part of the 8Ω series combination, the current flowing through it is the total current through that branch. Using Ohm's Law (I=RV):
I3Ω=8Ω6.0V=0.75A
The current through the 3Ω resistor is 0.75A.
2) If each cell has an internal resistance of 0.75Ω, determine the total resistance in the circuit:
Step 1: Calculate the total external resistance (Rext).
The 3Ω and 5Ω resistors are in series:
Rs1=3Ω+5Ω=8Ω
This Rs1 is in parallel with the 2Ω resistor. The equivalent resistance of this parallel combination is:
Rext=Rs1+2ΩRs1×2Ω=8Ω+2Ω8Ω×2Ω=10Ω16Ω2=1.6Ω
Step 2: Calculate the total internal resistance (rtotal).
The battery has an EMF of 6.0V. Assuming standard 1.5V cells, the number of cells in the battery is:
n=1.5V6.0V=4 cells
Each cell has an internal resistance of 0.75Ω. So, the total internal resistance for 4 cells in series is:
rtotal=n×rcell=4×0.75Ω=3.0Ω
Step 3: Determine the total resistance in the circuit.
The total resistance in the circuit is the sum of the total external resistance and the total internal resistance:
Rtotal=Rext+rtotal=1.6Ω+3.0Ω=4.6Ω
The total resistance in the circuit is $\boxed{\text{4.