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3 years ago

In the past, the intensity of the earth's magnetic field was: greater weaker same evidence is inconclusive

Physics

2 answers:

Fiesta28 [93]3 years ago

4 0

It's the same it never changes ever

lidiya [134]3 years ago

3 0

Permanent magnetism is lost when a substance is heated above a temperature known as the Curie point, and all but twenty-five miles of the crust is believed to be above the Curie point.The measured magnetism of the crustal rocks indicates that they do not supply nearly enough field strength to account for what we have.

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A student is experimenting with some insulated copper wire and a power supply. She winds a single layer of the wire on a tube wi

OverLord2011 [107]

Answer:

$P=214.7187\,W$

Explanation:

Given that:

Diameter of the solenoid, $D=10\,cm=0.1\,m$

length of the solenoid, $L=90\,cm=0.9\,m$

diameter of the wire, $d=0.1\,cm=10^{-3}\,m$

magnetic field at the center of the solenoid, $B=7.4\times 10^{-3}\,T$

Now we need the no. of turns incorporated in the length of 90 cm:

$N=\frac{Length\,\,of\,\,solenoid}{diameter\,\,of\,\, wire}$

$N=\frac{L}{d}$

$N=\frac{0.9}{10^{-3}}$

$N=900\,\,turns$

For solenoids we have:

$B=\mu.n.I$ ...............................(1)

where:

$\mu=$ permeability of the medium

n = no. of turns per unit length

I = current in the coil

So,

$n=\frac{900}{0.9}$

$n=1000\,turns\,.\,m^{-1}$

Now putting the respective values in the eq. (1)

$7.4\times 10^{-3}=4\pi\times10^{-7}\times 1000\times I$

$I=5.8887\,A$

For copper we have resistivity:

$\rho=1.72\times 10^{-8}\, \Omega.m$

We know that resistance is given by:

$R=\rho.\frac{l}{a}$ .....................................(2)

where:

l = length of the conducting wire

a = cross sectional area of the conducting wire

Now we need the length (l) of the wire:

Circumference of the solenoid,

$C=\pi.D$

$C=0.1\pi\,m$

$\therefore l=C\times N$

$l=90\pi\,m$

Cross-sectional area of wire:

$a=\pi.\frac{d^2}{4}$

$a=\pi. \frac{(10^{-3})^2}{4}\,m^2$

Resistance from eq. (2):

$R=1.72\times 10^{-8}\times \frac{90\pi}{\pi. \frac{(10^{-3})^2}{4}}$

$R=6.192 \,\Omega$

For power we have:

$P=I^2.R$

$P=5.8887^2 \times 6.192$

$P=214.7187\,W$

6 0

3 years ago

The eyepiece of a light microscope has a magnification level of 10x. If you were looking at a paramecium under the lowest-power

tester [92]

Answer:

The total magnification will be 40x.

Explanation:

As we know if the magnification of the eyepiece of a microscope be $m_{e}$ and that of the objective be $m_{o}$ , then the total magnification is given by

$m = m_{e} \times m_{o}$

Given, $m_{e} = 10x$ and $m_{o} = 4x$

Therefore total magnification is $m = 10 \times 4 = 40x$

4 0

3 years ago

A 3 kilogram block is sliding across the ground at a velocity of 8 meters per second. What is the momentum of the block?

oksano4ka [1.4K]

Answer:

24 kgm/s

Explanation:

Momentum (p) = mass x velocity

Mass = 3kg , velocity 8m/s

momentum (p) = 3kg x 8m/s

= 24kgm/s

4 0

3 years ago

How many boron atoms are there in 5 molecules of BF3? Hint: The symbol for boron is B. Submit

Thepotemich [5.8K]

Answer:

5 atoms of Boron

Explanation:

Boron makes up approximately 15.944% of the mass and the rest of the 84.056% is Fluorine. There is 5 Atoms because Boron atomic mass is 10.811 in 1 molecule of BF3 and you wanted 5 Molecules.

8 0

3 years ago

Read 2 more answers

Your life expectancy can be related to the overall well-being of your body your mind and your relationships with other people tr

Anettt [7]

yes if u let facts hold u down versus your mind and dreams. your ideas and dreams there can be no facts about the future unless u make that true!

6 0

3 years ago