In a series combination of resistors, the voltage (V) is divided among the resistors based on their individual resistance values. According to Ohm's Law (V = IR), the voltage across a resistor is directly proportional to the current (I) flowing through it and the resistance (R) of the resistor. In a series circuit, the same current flows through each resistor since there is only one path for the current to follow. Therefore, the voltage drop across each resistor is proportional to its resistance.
On the other hand, in a parallel combination of resistors, each resistor has the same voltage across it. This is because in a parallel circuit, the voltage across each branch is the same as the total voltage across the circuit. Since each resistor is connected across the same two points, they experience the same potential difference (voltage) across their terminals.
To understand this, we can consider the flow of current in a parallel circuit. When resistors are connected in parallel, the total current entering the parallel combination splits into separate currents flowing through each resistor. These currents add up to the total current entering the parallel combination. Since the voltage across each resistor is the same and the current flowing through each resistor can be different, the resistance of each individual resistor determines the amount of current flowing through it.
In summary, in a series combination, the voltage is divided among the resistors based on their individual resistances, while in a parallel combination, each resistor has the same voltage across it, but the current flowing through each resistor can vary based on their resistances.