Learning good work ethics will help you develop ____

The membrane that surrounds a certain type of living cell has a surface area of 5.1 x 10-9 m2 and a thickness of 1.4 x 10-8 m.

ziro4ka [17]

a) The charge on the outer surface is $1.2\cdot 10^{-12} C$

b) The number of ions is $7.5\cdot 10^6$

Explanation:

a)

The membrane behaves as a parallel plate capacitor, whose capacity is given by the equation

$C=\frac{k\epsilon_0 A}{d}$

where

k = 4.3 is the dielectric constant

$\epsilon_0 =8.85\cdot 10^{-12} F/m$ is the vacuum permittivity

$A=5.1\cdot 10^{-9} m^2$ is the surface area

$d=1.4\cdot 10^{-8} m$ is the distance between the two plates

Substituting,

$C=\frac{(4.3)(8.85\cdot 10^{-12})(5.1\cdot 10^{-9})}{1.4\cdot 10^{-8}}=1.4\cdot 10^{-11} F$

The capacity of the membrane is related to the potential difference between the two surfaces by

$C=\frac{Q}{\Delta V}$

where here we have

Q = excess charge on one surface

$\Delta V = 85.5 mV = 0.0855 V$ is the potential difference between the two surfaces

Solving for Q, we find

$Q=C\Delta V=(1.4\cdot 10^{-11})(0.0855)=1.2\cdot 10^{-12} C$

b)

We said that the net charge on the outer surface is

$Q=1.2\cdot 10^{-12} C$

The charge of one K+ ions is equal to the electron charge

$+e=1.6\cdot 10^{-19} C$

Therefore, the number of ions on the outer surface can be found by dividing the total charge by the charge of a single ion:

$N=\frac{Q}{e}=\frac{1.2\cdot 10^{-12}}{1.6\cdot 10^{-19}}=7.5\cdot 10^6$

Learn more about capacity:

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6 0

3 years ago

A hockey puck has a coefficient of kinetic friction of μk = .35. If the puck feels a normal force (FN) of 5 N, what is the frict

alina1380 [7]

Answer:

The frictional force is $F_f = 1.75 \ N$

Explanation:

From the question we are told that

The coefficient of kinetic force is μk = 0.35

The normal force felt by the puck is $F_N = 5 \ N$

Generally the frictional force that acts on the puck is mathematically represented as

$F_f = \mu_k * F_N$

=> $F_f = 0.35 * 5$

=> $F_f = 1.75 \ N$

3 0

3 years ago

A reaction occurs in which carbon combines with oxygen to form carbon dioxide. Is this a chemical reaction or a nuclear reaction

Tatiana [17]

Answer:

A. This is a chemical reaction because only the electrons were rearranged.

Explanation:

A.P.E.X

4 0

2 years ago

Read 2 more answers

Write a numerical expression for the emissive intensity (in W/m^2.sr) coming out of a tiny hole in an enclosure of surface tempe

stiks02 [169]

Answer:

6.0 × $10^{11}$ W/ $m^{2}$

Explanation:

From Wien's displacement formula;

Q = e A $T^{4}$

Where: Q is the quantity of heat transferred, e is the emissivity of the surface, A is the area, and T is the temperature.

The emissive intensity = $\frac{Q}{A}$ = e $T^{4}$

Given from the question that: e = 0.6 and T = 1000K, thus;

emissive intensity = 0.6 × $(1000)^{4}$

= 0.6 × 1.0 × $10^{12}$

= 6.0 × $10^{11}$ $\frac{W}{m^{2} }$

Therefore, the emissive intensity coming out of the surface is 6.0 × $10^{11}$ W/ $m^{2}$ .

3 0

2 years ago

1. Identify which of the following will not increase the current induced in a wire loop moving through a magnetic field. a. incr

djyliett [7]

Answer:

Rotating the loop until it is perpendicular to the field

Explanation:

Current is induced in a conductor when there is a change in magnetic flux.

The strength of the induced current in a wire loop moving through a magnetic field can be increased or decreased by the following methods:

By increasing the strength of the magnetic field there will be increased in the induced current. If the strength of the magnetic field is decreased then there is a decrease in induced current.

By increasing the speed of the wire there will be increased in the induced current. When the speed of the wire is decreased then there is a decrease in induced current.

By increasing the number of turns of the coil the strength of the induced current can be increased. when there is less number of turns in coils then there is a decrease in induced current.

Rotating the loop until it is perpendicular to the field will not increase the current induced in a wire loop moving through a magnetic field.

Therefore, the option is (c) is correct.

4 0

3 years ago

Learning good work ethics will help you develop _____.