Final answer:
To compare voltages in a circuit, we apply Kirchhoff's Voltage Law, which means summing voltage gains and drops around a loop. Points without components in between have the same voltage. Specific voltage comparisons across components require knowledge of the source voltage and component values.
Step-by-step explanation:
When analyzing a circuit with a voltage source and external load resistors, we apply Kirchhoff's Voltage Law (KVL), which states that the sum of the electrical potential differences (voltage) around any closed network is zero. This means as we travel around a closed loop in the circuit, the voltage increases when we cross a voltage source (V) and decreases when we pass across resistors due to the potential drops (I*R, where I is the current and R is the resistance).
In a circuit consisting of a single loop and no branches (Loop abcda), we can compare the voltages across different components by starting at point a and adding the voltage source at point ab, then subtracting the potential drops of resistors as we travel through the loop.
If there are no components between two points (like ad, ae, or bf), the voltage across these points will be the same. However, to compare the potential difference of other pairs like bc and ac, we need the circuit's specifics, such as source voltage and resistor values, which are not provided.
Without components between a and b, the voltage at a is the same as at b (voltage AB). Similarly, the voltage between any two points connected directly by a wire with no electrical components in between will be the same due to no potential drop. If components are present between two points (such as c and e if they lie across a resistor), then the voltage across those points will be equal to the current times the resistance according to Ohm's Law (V=IR).