The wireless system is operating at 2GHz. A base station and a mobile unit are separated by 16km. The maximum gain of the transmitting antenna at the base station is 20dB. The input power to the transmitter is 100W, and the power received by the antenna is 5nW. The antennas are aligned, and there are no re ections or loses. What will be the received power if the distance between the mobile unit and the base station increases to 20km?

Answer:

I = 3.81 x 10⁴ A

Explanation:

The magnetic field of a solenoid must be equal to the field of earth:

[tex]Field\ of\ Earth = Field\ of\ Solenoid\\52\ T = \mu n I\\I = \frac{52}{\mu n}[/tex]

where,

I = current passing through solenoid = ?

μ = permeability of free space = 4π x 10⁻⁷ N/A²

n = no. of turns per unit length = [tex]\frac{5000\ turns}{4.6\ m}[/tex] = 1086.96 /m

Therefore,

[tex]I = \frac{52\ T}{(4\pi\ x\ 10^{-7}\ N/A^2)(1086.96\ /m)}[/tex]

I = 3.81 x 10⁴ A

Answer:

okay

Explanation:

please I don't know

This question is incomplete, the complete question is;

A rifle fires a 2.10 × 10⁻² kg pellet straight upward, because the pellet rests on a compressed spring that is released when the trigger is pulled. The spring has a negligible mass and is compressed by 9.10 × 10⁻² m from its unstrained length. The pellet rises to a maximum height of 6.10 m above its position on the compressed spring. Ignoring air resistance, determine the spring constant.

Answer:

the spring constant is 303.5 N/m

Explanation:

Given the data in the question;

There is a potential energy associated with the spring;

we know that potential energy = kinetic energy

mgh = [tex]\frac{1}{2}[/tex]kx²

where k is the spring constant and x is the compression

as the pallet is fired, the spring gives kinetic energy which is converted into gravitational potential energy

so

m = 2.10 × 10⁻²

g = 9.81 m/s²

h = 6.10 m

x = 9.10 × 10⁻² m

we substitute

mgh = [tex]\frac{1}{2}[/tex]kx²

2.10 × 10⁻² × 9.81 × 6.10 =  [tex]\frac{1}{2}[/tex] × K × ( 9.10 × 10⁻² )²

1.256661 = 0.0041405 × K

K = 1.256661 / 0.0041405

K = 303.5 N/m

Therefore, the spring constant is 303.5 N/m

Answer:

The correct answer is - 93.24×10^4 kg/m^3.

Explanation:

Given:

height of cylinder: 50.5 mm

diameter = 52.0

then radius will be diameter/2 = 52/2 = 26

Formula:

Density = mass/ volume

Volume = πr^2h

solution:

Now the volume of a cylinder is v = (22/7)×r^2×h

= 22/7×26×26×50.5

= 107261.59 mm^3  

Now volume in cubic meter V =10.7261 ×10^(-5) m^3

So density d = m/V = 1/(10.7261 ×10^(-5))

Or d = 93.24×10^4 kg/m^3

Answer:

 θ₁ = θ₂,    n₁ sin θ₁ = n₂ sin  θ₂

instruments can be built that concentrate light on a small surface

Explanation:

The two laws of optical geometry have been known for quite some time.

The law of reflection states that when a ray of light reaches a surface, the reflected ray comes out at the same angle as the incident ray.

       θ₁ = θ₂

The law of refraction establishes how the direction of a light ray changes when it stops from one transparent medium to another.

           n₁ sin θ₁ = n₂ sin  θ₂

With any of these laws, instruments can be built that concentrate light on a small surface, which allows the weak light from the flares to be concentrated and objects to be measured and seen.

Electromagnetic radiation in its entire spectrum has the same properties, which is why telescopes of visible, infrared, and microwave light. Radio telescope, gamma rays use the same principles of the law of reflection and refraction. The main change between each instrument is the materials and which they are built,

a reflecting telescope must be built with a reflective surface, for example for microwaves metal surfaces are used

For gamma ray telescope it is preferred to constrict refracting telescope, therefore the material must be transparent to gamma rays

The radio telescope uses reflection and the surface is metallic, sometimes to reduce the weight the surface has holes smaller than the length of the donut that you want to measure.

Answer:

tex]2.898\times 10^{-7}\ \text{m}[/tex] ultraviolet region

[tex]2.898\times 10^{-10}\ \text{m}[/tex] x-ray region

Explanation:

T = Temperature

b = Constant of proportionality = [tex]2.898\times 10^{-3}\ \text{m K}[/tex]

[tex]\lambda[/tex] = Wavelength

[tex]T=10^4\ \text{K}[/tex]

From Wein's law we have

[tex]\lambda=\dfrac{b}{T}\\\Rightarrow \lambda=\dfrac{2.898\times 10^{-3}}{10^4}\\\Rightarrow \lambda=2.898\times 10^{-7}\ \text{m}[/tex]

The wavelength of the radiation will be [tex]2.898\times 10^{-7}\ \text{m}[/tex] and it is in the ultraviolet region.

[tex]T=10^7\ \text{K}[/tex]

[tex]\lambda=\dfrac{2.898\times 10^{-3}}{10^7}\\\Rightarrow \lambda=2.898\times 10^{-10}\ \text{m}[/tex]

The wavelength of the radiation will be [tex]2.898\times 10^{-10}\ \text{m}[/tex] and it is in the x-ray region.

Answer:

1/Re= 1/R1 + 1/R2

Explanation:

Two resistors are connected in parallel. If R1 and R2 represent the resistance in Ohms (Ω) of each resistor, then the total resistance R is given by  [tex]\mathbf{\dfrac{1}{R}=\dfrac{1}{R_1}+\dfrac{1}{R_2}}[/tex]. Thus, the rate of R changes when R₁ = 117 Ω and

R₂ = 112 Ω is 0.25 Ω/min

For a given resistor connected in parallel;

[tex]\mathbf{\dfrac{1}{R}=\dfrac{1}{R_1}+\dfrac{1}{R_2}}[/tex]

Making R from the left-hand side the subject of the formula, then:

[tex]\mathbf{R = \dfrac{R_1R_2}{R_1+R_2}}[/tex]

Given that:

Now, replacing the values in the above previous equation, we have:

[tex]\mathbf{R = \dfrac{13104}{229}}[/tex]

However, the differentiation of R with respect to time t will give us the rate at which R is changing when R1=117Ω and R2=112Ω.

So, by differentiating the given equation of the resistor in parallel with respect to time t;

[tex]\mathbf{\dfrac{1}{R}=\dfrac{1}{R_1}+\dfrac{1}{R_2}}[/tex],   we have:

[tex]\mathbf{\dfrac{1}{R^2}(\dfrac{dR}{dt})=\dfrac{1}{R_1^2}(\dfrac{dR_1}{dt})+\dfrac{1}{R_2^2}(\dfrac{dR_2}{dt})}[/tex]

[tex]\mathbf{(\dfrac{dR}{dt})=R^2 \Bigg[ \dfrac{1}{R_1^2}(\dfrac{dR_1}{dt})+\dfrac{1}{R_2^2}(\dfrac{dR_2}{dt})\Bigg]}[/tex]

[tex]\mathbf{\dfrac{dR}{dt}=(\dfrac{13104}{229})^2 \Bigg[ \dfrac{0.4}{117^2}+\dfrac{0.6}{112^2}\Bigg]}[/tex]

[tex]\mathbf{\dfrac{dR}{dt}=3274.44 \Bigg[ (7.7052 \times 10^{-5} )\Bigg]}[/tex]

[tex]\mathbf{\dfrac{dR}{dt}=0.25\ \Omega /min}[/tex]

Therefore, we can conclude that the rate at which R is changing R1=117Ω and R2=112Ω is 0.25 Ω/min

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Answer:

option b

Explanation:

........................

Answer:

J = 3.564 N.s

Explanation:

From  the given information:

angle θ = 27°

mass = 0.0200 kg

speed = 33.0 m/s

To determine the impulse applied using the equation:

J = m(2V cos  θ)

J = 0.0200 (2 × cos (27.0))

J = 0.0200 (2 × 0.8910)

J = 0.03564

J = 3.564 N.s

Answer:

the property of liquid are

1 they can flow from one place to another if surface is slanted

2 it cannot be compressed

Answer:

e)  A changing magnetic field produces an electric field.

Explanation:

Ok, we start with a magnetic field and let's study how it affects the motion of a single electron. As the magnetic field changes, it will cause an electromotive force, that moves the electron, and because now we have a moving electron, now we will have an electric field. (Such that the direction of the electromotive force opposes the direction in which the magnetic field changes). This also can be deduced if we look at the third Maxwell's equation:

dE/dx = -dB/dt

This says that the spatial change in an electric field depends on how the magnetic field changes as time pass.

Then the correct option is e)  A changing magnetic field produces an electric field.

Answer:

the speed of the textbook just before it hits the floor is 2.4 m/s

Explanation:

  Given the data in the question;

mass of pulley = 1.50 kg

radius of pulley = 0.240 m

mass of text book = 2.0 kg

height from which text book was released = 0.9 m

angular speed of the pulley = 10.0 rad/s

the speed of the textbook just before it hits the floor = ?

the speed of the textbook v = angular speed of the pulley × radius of pulley

we substitute

v = 10.0 rad/s × 0.240 m

v = 2.4 m/s

Therefore, the speed of the textbook just before it hits the floor is 2.4 m/s

Answer:

i believe its temperate

Explanation:

The climate zone that has hot summers, cold winters, and average amounts of precipitation throughout the year is the temperate climate zone. So, option C is correct.

Climatic zones are defined as the areas that have different climatic conditions over the world.

Here,

The climate zone that hot summers, cold winters and average amounts of precipitation throughout the year is the temperate climate zone.

The temperate climate zones are the areas that have mild temperature condition that are located between the subtropical and the polar regions. These are zones with moderate rainfall that is throughout the year. The temperature in this zone will change greatly between the summer and winter seasons. These zones are hotter during the summer and very cold during the winter.

The temperate zone has an average precipitation of 800 mm.

Hence,

The climate zone that has hot summers, cold winters, and average amounts of precipitation throughout the year is the temperate climate zone.

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Answer:

Option B. 0.016 Hz

Explanation:

From the question given above, the following data were obtained.

Period (T) = 60 s

Frequency (f) =?

Frequency and period are related according to the following equation:

Frequency = 1 / period

f = 1/T

With the above formula, we can obtain the frequency of the ride as follow:

Period (T) = 60 s

Frequency (f) =?

f = 1/T

f = 1/60

f = 0.016 Hz

Thus, the rider's frequency is 0.016 Hz

Answer:

r = 1,224 10⁻² m

Explanation:

For this exercise let's use Newton's second law

          F = m a

the force is magnetic

         F = q v x B

The bold letters indicate vectors, the module of this expesion is

          F = q v B

The direction of the force is found by the right hand rule

thumb points in the direction of the velicad + x

fingers extended in the direction of B -z

the palm is in the direction of the force + and

the acceleration of the proton is cenripetal

          a = v² / r

we substitute

          q v B = m v² / r

          r = [tex]\frac{m \ v}{q \ B}[/tex]

let's calculate

         r = [tex]\frac{1.7 \ 10^{-27} \ 5.760063 \ 10^7 }{1.6 \ 10^{-19} \ 0.5 }[/tex]

         r = 1,224 10⁻² m

Answer:

20000

Explanation:

Speed = Wavelength x Wave Frequency. In this equation, wavelength is measured in meters and frequency is measured in hertz (Hz), or number of waves per second. Therefore, wave speed is given in meters per second, which is the SI unit for speed.

Answer:

  a = [tex]\frac{m}{m+ \frac{1}{2} m_p} \ g \ sin \beta[/tex]  ,       t = [tex]\sqrt{ \frac{2d}{a} }[/tex]

Explanation:

To solve this exercise we must use Newton's second law

For the block

let's set a reference system with the x axis parallel to the plane

X axis

         Wₓ - T = m a

Y axis  

         N- W_y = 0

         N = W_y

for pulley

          ∑τ = I α

           T R = (½ m_p R²) α

let's use trigonometry for the weight components

         sin β = Wₓ / W

         cos β = W_y / W

         Wx = W sin β

angular and linear variables are related

          a = α R

          α = a / R

we substitute and group our equations

         W sin β - T = m a

         T R = ½ m_p R² (a / R)

         W sin β - T = m a

                        T = ½ m_p a

we solve the system of equations

         W sin β = (m + ½ m_p) a

          a = [tex]\frac{m}{m+ \frac{1}{2} m_p} \ g \ sin \beta[/tex]

let's find the time to travel the distance (d) through the block

          x = v₀ t + ½ a t²

          d = 0 + ½ a t²

          t = [tex]\sqrt{ \frac{2d}{a} }[/tex]

Answer:

It is the force that pulls down an object on the air

Answer: a downward pull on any object

Explanation:

Answer:

a) < 3 , -4 >

b) < 3 , -4 >

Explanation:

a) If you can imagine this, adding vectors is like putting them "tip to tail", where you put the beginning point of vector B to the end point of vector A (or vice versa).  Your new vector (A+B) would be from the "tip" of vector A to the "tail" of vector B.

Mathematically, this is the same as adding the x-components of each vector together as well as the y-components.

Vector A: 3 units along the positive x-axis: < 3 , 0 >

Vector B: 4 units along the negative y-axis: < 0 , -4 >

A+B = < 3 , 0 > + < 0 , -4 > = < (3+0) , (0+(-4)) > = < 3 , -4 >

b) Subtracting is like adding a negative, so you could use the same "tip to tail" visual by adding the negative of vector B instead (which is B in the opposite direction).

Vector A: < 3 , 0 >

Vector B: < 0 , -4 >

Vector -B: < 0 , 4 >

A-B = A+(-B) = < 3 , 0 > + < 0 , 4 > = < (3+0) , (0+4) > = < 3 , 4 >

Answer:

the correct answer is C     +, - , +

Explanation:

The electric field for positive charges is outgoing and for negative charges it is directed towards the charge.

Let's apply this to our case:

On plates A and B the field goes to the right, therefore plate A must be positive

In plates B and C the way it goes to the left, so the field is selected from it, this implies that plate C is positive

therefore plate B must be negative for both cases

when checking the correct answer is C     +, - , +

Answer:

P = 4.5 watts

Explanation:

Given that,

EMF of the circuit, E = 3 volt

The resistance  of the resistors, R = 2 ohms

We need to find the power of this circuit. The relation between power, emf and resistance is given by the formula as follows :

[tex]P=\dfrac{V^2}{R}[/tex]

Substitute all the values,

[tex]P=\dfrac{3^2}{2}\\\\P=4.5\ W[/tex]

So, the power of this circuit is equal to 4.5 watts.

Explanation:

Pencil is clearly an opaque object because, we cannot see through it. For example, take a pencil in your front. You will observe that, you are not able to see the objects behind it. And that is why you can say that pencil is an opaque object.

Answer:

A pencil is opaque

Explanation:

A pencil is opaque, because light cannot pass through it and shadow is created.

Answer:

(i) 100 m/s²

(ii) 450 m

Explanation:

From the question,

Using,

(i) a = (v-u)/t................. Equation 1

Where a = acceleration of the drone, v = final velocity of the drone, u = Initial velocity of the drone, t = time.

Given: v = 300 m/s, u = 0 m/s (from rest), t = 3 s

Substitute these values into equation 1

a = (300-0)/3

a = 300/3

a = 100 m/s²

Hence the acceleration of the drone is 100 m/s²

(ii) using,

s = ut+at²/2.................... Equation 2

Where s = distance traveled by the drone.

also substitute the values above into equation 2

s = 0(3)+100(3²)/2

s = 50×9

s = 450 m

Answer: 1.  walking across a carpet and touching a metal door handle            2. pulling your hat off and having your hair stand on end.

Explanation

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