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bagirrra123 [75]

2 years ago

7

What is the best alternative explanation for the dark matter in the milky way based on the observed orbital motions of stars and

gas?

1 answer:

Law Incorporation [45]2 years ago

6 0

I also wants to know about it

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Microwave ovens emit microwave energy with a wavelength of 12.1 cm. What is the energy of exactly one photon of this microwave r

EastWind [94]

Answer:

$1.64\cdot 10^{-24}J$

Explanation:

The energy of a photon is given by:

$E=\frac{hc}{\lambda}$

where

$h=6.63\cdot 10^{-34} Js$ is the Planck constant

$c=3\cdot 10^8 m/s$ is the speed of light

$\lambda$ is the wavelenght of the photon

For the microwave photons in this problem,

$\lambda=12.1 cm=0.121 m$

so their energy is

$E=\frac{(6.63\cdot 10^{-34}Js)(3\cdot 10^8 m/s)}{0.121 m}=1.64\cdot 10^{-24}J$

3 0

2 years ago

Calculate the self-inductance (in mH) of a 45.0 cm long, 10.0 cm diameter solenoid having 1000 loops. mH (b) How much energy (in

Karo-lina-s [1.5K]

Answer:

(a) The self inductance, L = 21.95 mH

(b) The energy stored, E = 4.84 J

(c) the time, t = 0.154 s

Explanation:

(a) Self inductance is calculated as;

$L = \frac{N^2 \mu_0 A}{l}$

where;

N is the number of turns = 1000 loops

μ is the permeability of free space = 4π x 10⁻⁷ H/m

l is the length of the inductor, = 45 cm = 0.45 m

A is the area of the inductor (given diameter = 10 cm = 0.1 m)

$A = \pi r^2 = \frac{\pi d^2}{4} = \frac{\pi \times (0.1)^2}{4} = 0.00786 \ m^2$

$L = \frac{(1000)^2 \times (4\pi \times 10^{-7}) \times (0.00786)}{0.45} \\\\L = 0.02195 \ H\\\\L = 21.95 \ mH$

(b) The energy stored in the inductor when 21 A current ;

$E = \frac{1}{2}LI^2\\\\E = \frac{1}{2} \times (0.02195) \times (21) ^2\\\\E = 4.84 \ J$

(c) time it can be turned off if the induced emf cannot exceed 3.0 V;

$emf = L \frac{\Delta I}{\Delta t} \\\\t = \frac{LI}{emf} \\\\t = \frac{0.02195 \times 21}{3} \\\\t = 0.154 \ s$

3 0

2 years ago

You are looking at yourself in a plane mirror, a distance of 3 meters from the mirror. Your brain interprets what you are seeing

Maslowich

Answer:6

Explanation:

5 0

2 years ago

If i ask wat r the application of simple machine some of u will say-----> Simple machines that are widely used include the wh

TiliK225 [7]

Answer:

DID NOT

UNDER STAND

Explan it a littlebit

3 0

2 years ago

Is an imaginary "line" from the earth to the moon a line, a ray, or a segment? Why?

igomit [66]

Answer;

- Line segment

Explanation;

"from earth to moon" implies endpoints at both locations and it is thus a line segment

A line extends forever in both directions, a line segment is just part of a line. It has two endpoints, and a ray starts at one point and continues on forever in one direction.

5 0

2 years ago