A sailor sends a sonar pulse to find out the depth of the ocean. If it takes 0.8 seconds from the time the pulse is sent until the echo is heard, how deep is the ocean here? (Sound travels at 1500 m/s in water; remember to account for the round trip.)

Cells in the nervous system have a potential difference of 70 mv across the cell membrane separating the interior of the cell from the extracellular fluid. this potential difference is maintained by ion pumps that move charged ions across the membrane. is this an emf? select the correct answer and explanation. 1)no. the ion pumps cannot separate charges; thus, they cannot create a potential difference. 2)yes. the ion pumps cannot separate charges, but they still can create a potential difference. 3)yes. the ion pumps can actively separate charge; thus, they can create a potential difference. 4)no. the ion pumps can separate charges, but they cannot create a potential difference.