Lightning Bolt
A stroke of lightning forming a 100-foot-long, 5-foot-wide Line blasts out from you in a direction you choose. Each creature in the Line makes a Dexterity saving throw, taking 8d6 Lightning damage on a failed save or half as much damage on a successful one.
Using a Higher-Level Spell Slot. The damage increases by 1d6 for each spell slot level above 3.
Lightning Bolt 5e 2024 vs. 2014 edition differences
The 2014 version specifies a 100-foot line with a range of "Self (100-foot line)" and ignites flammable objects. The 2024 version states range as "Self" with the line's dimensions in the description, and omits the igniting clause. Damage and scaling mechanics are essentially the same.