Cell Membrane Resistance The capacitance of biological membranes is about 1.0 μ F per cm 2 of membrane area, so investigators can determine the surface area of a cell membrane by using intracellular electrodes to measure the membrane’s capacitive reactance. An investigator applies a 1.0 μ A peak current at 40 kHz to a cell and measures the peak out-of-phase voltage—that is, the component of the voltage due to the capacitive reactance of the cell membrane—to be 0.16 V. What is the approximate capacitance of the cell membrane? A. 20 × 10 –11 F B. 10 × 10 –11 F C. 5.0 × 10 –11 F D. 2.5 × 10 –11 F
Cell Membrane Resistance The capacitance of biological membranes is about 1.0 μ F per cm 2 of membrane area, so investigators can determine the surface area of a cell membrane by using intracellular electrodes to measure the membrane’s capacitive reactance. An investigator applies a 1.0 μ A peak current at 40 kHz to a cell and measures the peak out-of-phase voltage—that is, the component of the voltage due to the capacitive reactance of the cell membrane—to be 0.16 V. What is the approximate capacitance of the cell membrane? A. 20 × 10 –11 F B. 10 × 10 –11 F C. 5.0 × 10 –11 F D. 2.5 × 10 –11 F
The capacitance of biological membranes is about 1.0 μF per cm2 of membrane area, so investigators can determine the surface area of a cell membrane by using intracellular electrodes to measure the membrane’s capacitive reactance. An investigator applies a 1.0 μA peak current at 40 kHz to a cell and measures the peak out-of-phase voltage—that is, the component of the voltage due to the capacitive reactance of the cell membrane—to be 0.16 V.
What is the approximate capacitance of the cell membrane?
Example
Two charges, one with +10 μC of charge, and
another with - 7.0 μC of charge are placed in
line with each other and held at a fixed distance
of 0.45 m. Where can you put a 3rd charge of +5
μC, so that the net force on the 3rd charge is
zero?
*
Coulomb's Law Example
Three charges are positioned as seen below. Charge
1 is +2.0 μC and charge 2 is +8.0μC, and charge 3 is -
6.0MC.
What is the magnitude and the direction of the force
on charge 2 due to charges 1 and 3?
93
kq92
F
==
2
r13 = 0.090m
91
r12 = 0.12m
92
Coulomb's Constant: k = 8.99x10+9 Nm²/C²
✓
Make sure to draw a Free Body Diagram as well
Chapter 26 Solutions
College Physics: A Strategic Approach Technology Update, Books a la Carte Plus Mastering Physics with Pearson eText -- Access Card Package (3rd Edition)
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