Q. During the transmission of nerve impulse through a nerve fibre, the potential on the inner side of the plasma membrane has which type of electric change?
A) first positive, then negative and continue to be positive
B) first negative, then positive and continue to be positive
C) first positive, then negative and again back to positive
D) first negative, then positive and again back to negative
Explanation
[Solution from source] At rest the inside of the axon is negative (about -70 mV); during the action potential Na⁺ influx makes it positive, and K⁺ efflux during repolarisation returns it to negative. It does not stay positive after the impulse passes. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.