Question

1. The headlights on an automobile are 125 cm apart. At what distance will the lights appear to be just resolvable to a person whose nocturnal pupils are 4.5 mm in 2. Assume the range of pupil variation during adaptation of a normal eye is from 2.0 to 7.1 mm. What is the corresponding range of distances over which it can detect 3. Two stars make an angle of 1 x 10-3 radians at the eye of an observer. A person, who can just distinguish two spots 0.35 cm apart at a distance of 8 m, views the 4. Given that the regeneration constant of rhodopsin is 0.14 min1, calculate (a) the regeneration half-life; (b) the fraction of molecules that have not reconstituted after diameter? Assume an average wavelength of 550 nm the separation of objects 5 cm apart? Assume an average wavelength of 550 nm stars. Can he/she distinguish them as two distinct objects? (i) 2.5 min, () 6.0 min, and (ili) 9.0 min, and (C) the fraction of molecules that have been regenerated after (i) 2.5 min, (ii) 6.0 min, and (ii) 9.0 min 5. Given that the average number of photons absorbed by the eye is 3, (a) calculate the absorption probability for 0, 1, 2, and 3 photons, (b) what is the probability that fewer than 4 photons are absorbed, and (c) what is the probability that more than 3 photons are absorbed? 6. Calculate the axoplasm resistance of a 1-cm-long segment of a) unmyelinated axon of radius of 2 μm and (b) myelinated axon of radius 2 μm The resistivity is 2.0 ohm-m. 7. An unmyelinated segment of axon has a radius of 2 um and a length of 1 cm. (a) Find its membrane capacitance and membrane leakage resistance. (b) Find the membrane capacitance and membrane leakage resistance of a myelinated segment of axon of radius 2 μm and length 1 cm. 8. An axon membrane is 8.0 nm thick. In the resting state the axon potential is -90 mV. What is the magnitude of the electric field in the membrane? 9. A membrane has a potential difference of 95 mV across it. How much charge per square meter is located on either side if it is (a) myelinated and (b) unmyelinated? 10. (a) How many potassium ions are there inside a 1 cm long segment of an axon of radius 3.0 μm? (b) How many sodium ions are there in a 1 cm length of an axon of radius 4.5 um? (c) The concentration of an ion is 85 mole/m3. How many ions are there in 1 m3? 11. A 1 cm long segment of unmyelinated axon has a capacitance of 3.5 nF. (a) If the axoplasm potential changes from -95 mV to +40 mV, by how much do the excess charges on either side of the membrane change? (b) If this change is due to an influx of sodium ions, how many sodium ions enter the axon?

Answer 1

No: 22A Haee -350 X 10mm H5mm min ;-e., 시9.2126 inch H92126 33006 . 366318 pnCh