Which type of brain waves are smaller and faster than alpha waves and indicate mental activity when awake and alert?

• A. Alpha waves
• B. Beta waves
• C. Theta waves
• D. Delta waves

Answer: (B)

When the brain is actively processing and you’re awake and alert, the EEG shows faster, lower-amplitude activity compared with relaxed states. These faster, smaller waves are beta waves. They typically run about 12 to 30 Hz and reflect active cognition—thinking hard, concentrating, solving problems, or planning. In contrast, alpha waves (around 8-12 Hz) appear during relaxed wakefulness with eyes closed and aren’t tied to focused mental activity. Theta waves (roughly 4-7 Hz) are slower and associated with drowsiness or light sleep, while delta waves (0.5-4 Hz) are the slowest and dominate deep sleep. So the described type is beta waves.