Three identical light bulbs are connected in series. Which of the following statements are true (circle all
that apply):
a. The total circuit resistance equals the sum of the individual resistors.
b. The current decreases the same amount as it passes through each bulb.
c. The voltage drop across each bulb is the same.
d. The first bulb shines more brightly than the last one.

a. The total circuit resistance equals the sum of the individual resistors.

c. The voltage drop across each bulb is the same.

Explanation:

Electric devices are said to be connected in series when they are connected along the same branch.

In such scenario, the current flowing through the devices is the same.

Moreover, the total resistance of N resistors in series is given by the sum of the individual resistances:

Given that, we can now analyze the 4 statements:

a. The total circuit resistance equals the sum of the individual resistors.  --> TRUE, as we said above

b. The current decreases the same amount as it passes through each bulb.  --> FALSE, the current does not decrease.

c. The voltage drop across each bulb is the same.  --> TRUE, since the voltage drop across each bulb is

where I is the current (the same in the 3 bulbs) and R the resistance (the same for each bulb)

d. The first bulb shines more brightly than the last one. --> FALSE: since the 3 bulbs have the same current, they shine the same