Introduction:
In a series combination of resistors, the resistors are connected one after another, such that the current flowing through each resistor is the same. The total resistance in a series combination is determined by the sum of individual resistances.

Explanation:
When resistors are connected in series, the total resistance increases. This can be explained by considering the flow of current through the resistors and the voltage across them.

Current Flow:
In a series combination, the same current flows through each resistor. This is because the current has only one path to follow, and it cannot split or divert. Therefore, the current remains constant throughout the series circuit.

Voltage Distribution:
When resistors are connected in series, the total voltage across the combination is equal to the sum of the individual voltage drops across each resistor. The voltage drop across a resistor is directly proportional to its resistance. So, if the resistance increases, the voltage drop across that resistor also increases.

Ohm's Law:
According to Ohm's Law, the voltage across a resistor is equal to the product of current and resistance (V = I * R). Since the current is constant in a series combination, a higher resistance will result in a higher voltage drop across that resistor.

Total Resistance:
The total resistance in a series combination is equal to the sum of the individual resistances. This can be derived from Ohm's Law by rearranging the formula to R = V / I. As the voltage across each resistor increases with an increase in resistance, the total voltage required to drive the same current through the series combination also increases.

Therefore, the total resistance in a series combination increases because the voltage drop across each resistor increases with an increase in resistance.