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3 years ago

I don't understand when to use the formule with the constant k, and when to use the formula without it.

Physics

1 answer:

White raven [17]3 years ago

3 0

Answer:

This appears to be the formula for the electrical force between 2 objects.

You need this constant to calculate the electrical force between 2 charged objects.

Note that k = (1 / 4 * π ∈0)

∈0 is called the permittivity constant and ∈0 = 8.85E-12 farad/m

k = ( 1 / (4 * 3.28 * 8.85E-12) = 8.99E9

This makes F reasonably easy to remember as

F = 9E9 Q1 * Q2 / R^2 Newtons for the electrical force between Q! and Q2 separated by R

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Additional help:
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3 years ago

Read 2 more answers

A radar for tracking aircraft broadcasts a 12 GHz microwave beam from a 2.0-m-diameter circular radar antenna. From a wave persp

NISA [10]

A) 750 m

First of all, let's find the wavelength of the microwave. We have

$f=12GHz=12\cdot 10^9 Hz$ is the frequency

$c=3.0\cdot 10^8 m/s$ is the speed of light

So the wavelength of the beam is

$\lambda=\frac{c}{f}=\frac{3\cdot 10^8 m/s}{12\cdot 10^9 Hz}=0.025 m$

Now we can use the formula of the single-slit diffraction to find the radius of aperture of the beam:

$y=\frac{m\lambda D}{a}$

where

m = 1 since we are interested only in the central fringe

D = 30 km = 30,000 m

a = 2.0 m is the aperture of the antenna (which corresponds to the width of the slit)

Substituting, we find

$y=\frac{(1)(0.025 m)(30000 m)}{2.0 m}=375 m$

and so, the diameter is

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B) 0.23 W/m^2

First we calculate the area of the surface of the microwave at a distance of 30 km. Since the diameter of the circle is 750 m, the radius is

$r=\frac{750 m}{2}=375 m$

So the area is

$A=\pi r^2 = \pi (375 m)^2=4.42\cdot 10^5 m^2$

And since the power is

$P=100 kW = 1\cdot 10^5 W$

The average intensity is

$I=\frac{P}{A}=\frac{1\cdot 10^5 W}{4.42\cdot 10^5 m^2}=0.23 W/m^2$

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3 years ago

When y⁷ is multiplied by y⁹ the answer is?

Allushta [10]

Answer:

y^16

Explanation:

who need to add the exponents only

7 + 9 = 16

therefore, the answer is y^16

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2 years ago

A 75 W lightbulb is being run on a 110 V outlet. Determine the resistance of the lightbulb. Provide a detailed description of th

Sauron [17]

Power is defined as

P = I*V

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V = I*R , Then

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We solve for R,

R = (110 V)²/ 75W = 161.33 ohms

8 0

3 years ago