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ra1l [238]
3 years ago
5

A uniformly charged ball of radius a and charge –Q is at the center of a hollowmetal shell with inner radius b and outer radius

c. The hollow sphere has a netcharge of +2Q. Determine the electric field strength in the four regions:Part A
Determine the electric field strength in the region r?a. Give your answer as a multiple of Q/?0.

Express your answer in terms of some or all of the variables a, b, c, r, and the constant ?.

Park B

Determine the electric field strength in the region a
Express your answer in terms of some or all of the variables a, b, c, r, and the constant ?.

Part C

Determine the electric field strength in the region b
Part D

Determine the electric field strength in the region c
Express your answer in terms of some or all of the variables a, b, c, r, and the constant ?.
Physics
1 answer:
vlabodo [156]3 years ago
3 0

Answer:

<u>r < a:</u>

E = \frac{1}{4\pi \epsilon_0}\frac{Qr}{a^3}

<u>r = a:</u>

E = \frac{1}{4\pi a^2}\frac{Q}{\epsilon_0}

<u>a < r < b:</u>

E = \frac{1}{4\pi \epsilon_0}\frac{Q}{r^2}

<u>r = b:</u>

E = \frac{1}{4\pi b^2}\frac{Q}{\epsilon_0}

<u>b < r < c:</u>

E = 0

<u>r = c:</u>

E = \frac{1}{4\pi \epsilon_0}\frac{Q}{c^2}

<u>r < c:</u>

E = \frac{1}{4\pi \epsilon_0}\frac{Q}{r^2}

Explanation:

Gauss' Law will be applied to each region to find the E-field.

\int \vec{E}d\vec{a} = \frac{Q_{encl}}{\epsilon_0}

An imaginary sphere is drawn with radius r, which is equal to the point where the E-field is asked. The area of this imaginary sphere is multiplied by E, and this is equal to the charge enclosed by this imaginary surface divided by ε0.

<u>r<a:</u>

Since the ball is uniformly charged and not hollow, then the enclosed charge can be found by the following method: If the total ball has a charge -Q and volume V, then the enclosed part of the ball has a charge Q_enc and volume V_enc. Then;

\frac{Q}{V} = \frac{Q_{encl}}{V_{encl}}\\\frac{Q}{\frac{4}{3}\pi a^3} = \frac{Q_{encl}}{\frac{4}{3}\pi r^3}\\Q_{encl} = \frac{Qr^3}{a^3}

Applying Gauss' Law:

E4\pi r^2 = \frac{-Qr^3}{\epsilon_0 a^3}\\E = -\frac{1}{4\pi \epsilon_0}\frac{Qr}{a^3}\\E = \frac{r}{4\pi a^3}\frac{Q}{\epsilon_0}

The minus sign determines the direction of the field, which is towards the center.

<u>At r = a: </u>

E = \frac{1}{4\pi a^2}\frac{Q}{\epsilon_0}

<u>At a < r < b:</u>

The imaginary surface is drawn between the inner surface of the metal sphere and the smaller ball. In this case the enclosed charge is equal to the total charge of the ball, -Q.

<u />E4\pi r^2 = \frac{-Q}{\epsilon_0}\\E = -\frac{1}{4\pi \epsilon_0}\frac{Q}{r^2}<u />

<u>At r = b:</u>

<u />E = -\frac{1}{4\pi b^2}\frac{Q}{\epsilon_0}<u />

Again, the minus sign indicates the direction of the field towards the center.

<u>At b < r < c:</u>

The hollow metal sphere has a net charge of +2Q. Since the sphere is a conductor, all of its charges are distributed across its surface. No charge is present within the sphere. The smaller ball has a net charge of -Q, so the inner surface of the metal sphere must possess a net charge of +Q. Since the net charge of the metal sphere is +2Q, then the outer surface of the metal should possess +Q.

Now, the imaginary surface is drawn inside the metal sphere. The total enclosed charge in this region is zero, since the total charge of the inner surface (+Q) and the smaller ball (-Q) is zero. Therefore, the Electric region in this region is zero.

E = 0.

<u>At r < c:</u>

The imaginary surface is drawn outside of the metal sphere. In this case, the enclosed charge is +Q (The metal (+2Q) plus the smaller ball (-Q)).

E4\pi r^2 = \frac{Q}{\epsilon_0}\\E = \frac{1}{4\pi \epsilon_0}\frac{Q}{r^2}

<u>At r = c:</u>

E = \frac{1}{4\pi \epsilon_0}\frac{Q}{c^2}

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<h3>What is a perpetual motion machine?</h3>

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What is the resistance ofa wire made of a material with resistivity of 3.2 x 10^-8 Ω.m if its length is 2.5 m and its diameter i
Katarina [22]

R = 0.407Ω.

The resistance  R of a particular conductor is related to the resistivity ρ of the material by  the equation R = ρL/A, where ρ is the material resistivity, L is the length of the material and A is the cross-sectional area of ​​the material.

To calculate the resistance R of a wire made of a material with resistivity of 3.2x10⁻⁸Ω.m, the length of the wire is 2.5m and its diameter is 0.50mm.

We have to use the equation R = ρL/A but first we have to calculate the cross-sectional area of the wire which is a circle. So, the area of a circle is given by A = πr², with r = d/2. The cross-sectional area of the wire is A = πd²/4.  Then:

R =[(3.2x10⁻⁸Ω.m)(2.5m)]/[π(0.5x10⁻³m)²/4]

R = 8x10⁻⁸Ω.m²/1.96x10⁻⁷m²

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5 0
3 years ago
Calculate the density of a material that has a mass of 52.457 and a volume of 13.5
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3 years ago
Cuanto es tres por dos más cinco<br>3 * 2 + 5 es igual ​
Simora [160]

Answer:

3×2+5=11

Explanation:

3×2+5=

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2 years ago
A. Compute the torque developed by an industrial motor whose ouputis 150kW at an angular speed of 4000 rev/min.
Gnom [1K]

Answer:

A. τ = 358 N.m

B. m = 73kg

C. V = 209.5 m/s

Explanation:

Let's first convert angular speed to rad/s:

ω = 4000 rev/min * 2π / 60 = 419 rad/s

Since Power is P = τ * ω,

τ = P / ω = 358 N.m

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Solving for m:

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For part C:

V = ω * R = 209.5 m/s

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