How does the voltage change when resistors are connected in series?

To better understand this, let's consider two resistors connected in series:

Let's say R1 is the resistance of the first resistor.

Let's say R2 is the resistance of the second resistor.

V1 is the voltage drop across R1.

V2 is the voltage drop across R2.

If a total voltage, V_total, is applied across the series combination, the current flowing through both resistors will be the same (let's call it I). According to Ohm's law, the voltage drop across a resistor is equal to the product of the current and the resistance:

V1 = I * R1

V2 = I * R2

The total voltage (V_total) is the sum of the voltage drops across each resistor:

V_total = V1 + V2

V_total = I * R1 + I * R2

V_total = I * (R1 + R2)

So, when resistors are connected in series, the total voltage across the combination is equal to the sum of the individual resistances. In general, for n resistors connected in series, the total voltage (V_total) would be:

V_total = I * (R1 + R2 + R3 + ... + Rn)

Keep in mind that the current remains constant in a series circuit, while the voltage adds up across the resistors.