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Vlad [161]
3 years ago
12

What happens to matter during chemical changes?

Physics
1 answer:
Harrizon [31]3 years ago
7 0
The object that goes through chemical change, changes completely to where you can not change it back to its original form. Physical change you can undo
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Copper and aluminum are being considered for a high-voltage transmission line that must carry a current of 60.7 A. The resistanc
lisov135 [29]

Answer:

a) The magnitude JJ of the current density for a copper cable is 5.91 × 10⁵A.m⁻²

b)The mass per unit length \lambdaλ for a copper cable is 0.757kg/m

c)The magnitude J of the current density for an aluminum cable is 3.5 × 10⁵A/m²

d)The mass per unit length \lambdaλ for an aluminum cable is 0.380kg/m

Explanation:

The expression for electric field of conductor is,

E =  \frac{V}{L}

The general equation of voltage is,

V = iR

The expression for current density in term of electric field is,

J = \frac{E}{p}

Substitute (V/L)  for E in the above equation of current density.

J = \frac{V}{pL} ------(1)

Substitute iR for V in equation (1)

J = \frac{iR}{pL} ------(2)

Substitute 1.69 × 10⁸ Ω .m for p

50A for i

0.200Ω.km⁻¹ for (R/L) in eqn (2)

J = \frac{(50) (0.200\times 10^-^3) }{1.69 \times 10^-^8 } \\\\= 5.91 \times 10^5A.m^-^2

The magnitude JJ of the current density for a copper cable is 5.91 × 10⁵A.m⁻²

b) The expression for resistivity of the conductor is,

p = \frac{RA}{L}

A = \frac{pL}{R}

The expression for mass density of copper is,

m = dV

where, V is the density of the copper.

Substitute AL for V in equation of the mass density of copper.

m=d(AL)

m/L = dA

λ is use for (m/L)

substitute,

pL/R for A  and λ is use for (m/L) in the eqn above

\lambda = d\frac{p}{\frac{R}{L} } ------(3)

Substitute 0.200Ω.km⁻¹ for (R/L)

8960kgm⁻³  for d and 1.69 × 10⁸ Ω .m

\lambda = (8960) \frac{(1.69 \times 10^-^8 }{0.200\times 10^-^3} \\\\= 0.757kg.m^-^1

c) Using the equation (2) current density for aluminum cable is,

J = \frac{iR}{pL}

p is the resistivity of the aluminum cable.

Substitute 2.82 × 10⁻⁸Ω.m for p ,

50A for i and 0.200Ω.km⁻¹ for (R/L)

J = \frac{(50)(0.200\times10^-^3) }{2.89\times 10^-^8} \\\\= 3.5 \times10^5A/m^2

The magnitude J of the current density for an aluminum cable is 3.5 × 10⁵A/m²

d) Using the equation (3) mass per unit length for aluminum cable is,

\lambda = d\frac{p}{\frac{R}{L} }

p is the resistivity and is the density of the aluminum cable.

Substitute 0.200Ω.km⁻¹ for (R/L), 2700 for d and 2.82 × 10⁻⁸Ω.m for p

\lambda = (2700) \frac{(2.82 \times 10^-^8) }{(0.200 \times 10^-^3) } \\\\= 0.380kg/m

The mass per unit length \lambdaλ for an aluminum cable is 0.380kg/m

7 0
3 years ago
Read 2 more answers
Which is the best example of the use of imagery in a sentence?
Talja [164]

Answer:

Common Examples of Imagery

Taste: The familiar tang of his grandmother's cranberry sauce reminded him of his youth. Sound: The concert was so loud that her ears rang for days afterward. Sight: The sunset was the most gorgeous they'd ever seen; the clouds were edged with pink and gold.

I hope it's helpful!

6 0
3 years ago
As keisha runs the generator, which best describes what should happen to the needle that measures electric current? it will move
SOVA2 [1]

The diagram shows a simple electric generator. The needle that measures electric current will move back and forth between a largely positive and a large negative value.

  • What is an electric generator?
  1. An electric generator is physically equivalent to an electric motor. but it converts mechanical energy into electrical energy.
  2. The electrical field generated is dependent on the inclination of the wire with respect to magnetic field lines, and this inclination changes over time,

because of that she will experience a varying electrical field, and thus a varying electric current will be zero.

The maximum positive value will occur when the wire is perpendicular to the magnetic field lines after one-fourth of rotation, and then zero.

Hence option C is correct.

The diagram shows a simple electric generator. The needle that measures electric current will move back and forth between a largely positive and a large negative value.

 

Learn more about electric generator here:

<u>brainly.com/question/12296668</u>

<u />

#SPJ4

6 0
2 years ago
Which statement is true about tomato juice? A) It is an acid. B) It has a pH of 7.0. Eliminate C) It is strongly basic in nature
adoni [48]
The answer would be A. It is an acid.
7 0
3 years ago
An alternator consists of a coil of area A with N turns that rotates in a uniform field B around a diameter perpendicular to the
svet-max [94.6K]

Answer:

(a): emf = \rm 2\pi f NBA\sin(2\pi ft).

(b): Amplitude of alternating voltage = 20.942 Volts.

Explanation:

<u>Given:</u>

  • Area of the coil = A.
  • Number of turns of coil = N.
  • Magnetic field = B
  • Rotation frequency = f.

(a):

The magnetic flux through the coil is given by

\phi = \vec B \cdot \vec A=BA\cos\theta

where,

\vec A = area vector of the coil directed along the normal to the plane of the coil.

\theta = angle between \vec B and \vec A.

Assuming, the direction of magnetic field is along the normal to the plane of the coil initially.

At any time t, the angle which magnetic field makes with the normal to the plane of the coil is 2\pi ft

Therefore, the magnetic flux linked with the coil at any time t is given by

\phi(t) = NBA\cos(2\pi ft)

According to Faraday's law of electromagnetic induction, the emf induced in the coil is given by

e=-\dfrac{d\phi}{dt}\\=-\dfrac{d(NBA\cos(2\pi ft))}{dt}\\=-NBA(-2\pi f\sin(2\pi ft))\\=2\pi f NBA\sin(2\pi ft).

(b):

The amplitude of the alternating voltage is the maximum value of the emf and emf is maximum when \sin(2\pi ft)=1.

Therefore, the amplitude of the alternating voltage is given by

e_o = 2\pi ft NBA.

We have,

N=100\\A=10^{-2}\ m^2\\B=0.1\ T\\f=2000\ rev/ min = 2000\times \dfrac{1}{60}\ rev/sec=33.33\ rev/sec.

Putting all these values,

e_o = 2\pi \times 33.33\times 100\times 0.1\times 10^{-2}=20.942\ Volts.

7 0
3 years ago
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