Why are two identical light bulbs less bright than one when connected in series?

When two identical light bulbs are connected in series, the total resistance of the circuit increases, therefore the current in the circuit decreases and the bulbs burn less brightly.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.