Microwaves operate at a frequency of 2.40 GHz. Find the minimum thickness for a plastic tray with a refractive
index of 1.45 that will cause enhanced reflection of microwaves incident normal to the tray.

Answers

Answer 1

Answer:

y (lambda) = c / f     incident wavelength

y = 3 * E8 / 2.4 * E9 = .125 m    incident wavelength

y' = .125 / 1.45 = .0862 m    wavelength inside of tray

T = y' / 4     thickness required for phase change at bottom

T = .0862 m / 4 = .0261 m = 2.61 cm


Related Questions


State one effect of increase in heat for a temperature range of 50°C to 100°C
on Plastic

Answers

Answer:

why is fraction called a necessary evil

The heat for a temperature in plastic increases at the range of 50°C to 100°C then the plastic decreases its stiffness or flexural modulus.

It is given that the temperature is increased from 50°C to 100°C that means temperature is increasing.

It is required to state the effect of increase in heat on plastic.

What will be the effect of increase in heat for a temperature range of 50°C to 100°C on Plastic?

The plastic starts to lose its stiffness or we say that it converts into a softened material as long as we increase the temperature of the material.

So if we increase the temperature too much or exceed above the limit of temperature range then it will distort.

Also there are many qualities that can be affected by increasing the temperature like mechanical property, material fatigue or chemical phenomenon.

Therefore, the heat for a temperature range of 50°C to 100°C

Plastic increases then the plastic decreases its stiffness or flexural modulus.

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Tick (3) the correct statement about electrostatic charges.
(a) Earthing causes positive charges to flow from the object to the ground.
(b) Similar types of electric charges attract one another.
(c) An electroscope is used to determine the presence of electrostatic charges.

Answers

Answer:

similar type of electric charges attract one another

I think this is a coorect staement

Answer:

C ) An electroscope is used to determine the presence of electrostatic charges

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

Answers

Dot, dot, dot, dot, lol

Object A has a mass of 5 kg and a velocity of 6 m/s to the east while Object 1 point B has a mass of 12 kg and velocity 0.6 m/s also to the east. What is the momentum of the system? (Let east be positive)
help plss I got family

Answers

Answer:

Momentum of system = 37.2 Kgm/s.

Explanation:

Given the following data;

Mass A = 5 kgVelocity A = 6 m/sMass B = 12 kgVelocity B = 0.6 m/s

To find the momentum of the system;

Momentum can be defined as the multiplication (product) of the mass possessed by an object and its velocity. Momentum is considered to be a vector quantity because it has both magnitude and direction.

Mathematically, momentum is given by the formula;

Momentum = mass * velocity

For object A;

Momentum A = 5 * 6

Momentum A = 30 Kgm/s

For object B;

Momentum B = 12 * 0.6

Momentum B = 7.2 Kgm/s

Next, we would determine the momentum of this system using the formula;

Momentum of system = Momentum A + Momentum B

Substituting the values into the formula, we have;

Momentum of system = 30 + 7.2

Momentum of system = 37.2 Kgm/s.

the force of attraction between the earth and objects on it is called..

Answers

Answer: gravitational pull? gravity

Explanation:

Phương trình chuyển động thẳng đều của một chất điểm có dạng: x = 2t – 10. (x: km, t: h). Quãng đường đi được của chất điểm sau 2h là bao nhiêu?

Answers

Answer:

Distance cover in 2  hour = 6 kilometer

Explanation:

Given equation:

x = 2t - 10

where

x = kilometer

t = hour

Find:

Distance cover in 2  hour

Computation:

T = 2

So,

x = 2t - 10

x = 2(2) - 10

x = 4 - 10

x = -6

Distance cover in 2  hour = 6 kilometer

Answer:

The distance is 6 km.

Explanation:

The equation of uniform linear motion of a particle has the form: x = 2t – 10. (x: km, t: h). What is the distance traveled by the particle after 2 hours?

x = 2t - 10

distance traveled after t = 2 hours

Substitute t = 2 in the given expression

x = 2 x 2 - 10

x = 4 - 10

x = - 6 km

So, the distance is 6 km.

Assuming Faraday constant to be 96500c/mol and relative atomic mass of copper 63,calculate the mass of copper liberated by 2A current in 5min.ans 0.196gm ​

Answers

Answer: The mass of copper liberated is 0.196 g.

Explanation:

The oxidation half-reaction of copper follows:

[tex]Cu\rightarrow Cu^{2+}+2e^-[/tex]

Calculating the theoretical mass deposited by using Faraday's law, which is:

[tex]m=\frac{M\times I\times t(s)}{n\times F}[/tex] ......(1)

where,

m = actual mass deposited = ? g

M = molar mass of metal = 63 g/mol

I = average current = 2 A

t = time period in seconds = 5 min = 300 s (Conversion factor: 1 min = 60 sec)

n = number of electrons exchanged = 2

F = Faraday's constant = 96500 C/mol

Putting values in equation 1, we get:

[tex]m=\frac{63 g/mol\times 2A\times 300s}{2\times 96500 C/mol}\\\\m=0.196g[/tex]

Hence, the mass of copper liberated is 0.196 g.

Please help me with these I might need more than only 1 person to answer ​

Answers

Explanation:

a) copper

b) olive oil

Hope it helps✌✌

An ant moves towards the plane mirror with speed of 2 m/s & the mirror is moved towards the ant with the same speed. What is the relative velocity between the ant and its image?​

Answers

Speed of ant-V_a=2m/sSpeed of mirror =v_b=2m/s

We know

[tex]\boxed{\sf Relative\:velocity(V_{AB})=V_A-V_B}[/tex]

[tex]\\ \sf\longmapsto V_{AB}=2-2[/tex]

[tex]\\ \sf\longmapsto V_{AB}=0m/s[/tex]

The vector difference between the velocities of two bodies : the velocity of a body with respect to another regarded as being at rest  compare relative motion

[tex]Relative velocity $\left(\mathrm{V}_{\mathrm{AB}}\right)=\mathrm{V}_{\mathrm{A}}-\mathrm{V}_{\mathrm{B}}$$$\begin{aligned}&\longmapsto \mathrm{V}_{\mathrm{AB}}=2-2 \\&\longmapsto \mathrm{V}_{\mathrm{AB}}=0 \mathrm{~m} / \mathrm{s}\end{aligned}$$[/tex]

What is relative velocity and its unit?

The relative velocity of an object with respect to another is the velocity with which one object moves with respect to another object. The unit of velocity can be referred to as the ratio of unit of distance and that of time. The SI unit of Relative velocity is meter per second.

What is absolute velocity?

The concept of absolute velocity is mainly used in turbomachinery design and defines the velocity of a fluid particle in relation to the surrounding, stationary environment. Together with the relative velocity (w) and the circumferential speed (u), it forms the velocity triangle.

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Clois what is the weight of a body in the earth, if its weig is 5Nin moon?

Answers

Explanation:

because the moon has less mass than earth, the force due to gravity at the lunar surface is only about 1/6 that on earthso,the weight of a body on earth is 6×5N =30N

What is the centripetal acceleration of a point on the perimeter of a bicycle wheel diameter 70.0 cm when the bike is moving 8.0 m/s? (160 m/s)

Answers

It’s 180 m/s^2 dude. I think I have you in my class lol.

The centripetal acceleration of an object is due to the changing velocity in a circular path and the centripetal acceleration of the bicycle is 182.85 m/s².

What is Centripetal acceleration?

Centripetal acceleration of an object can be defined as the property of the motion of an object which is traversing a circular path. Any object which is moving in a circular path and has an acceleration vector pointed towards the center of that circular path is known as Centripetal acceleration.

The centripetal acceleration of an object can be calculated by the formula:

ac = v²/ r

where, ac = centripetal acceleration,

v = velocity of the object,

r = radius of the circular path

The centripetal acceleration of the object will be:

ac = (8)²/ r

radius = diameter/ 2

radius = 70/ 2

radius = 35cm or 0.35 m

ac = 64/ 0.35

ac = 182.85 m/s²

Therefore, the centripetal acceleration of the bicycle will be 182.85 m/s².

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Examine the motion map. One animal is an antelope that is already running. The other is a cheetah that starts running after the antelope passes it. Does A or B represent the motion of the cheetah?

Answers

Answer:

A although am not seeing the cheetah

In a lunar experiment, a 950-g aluminum (920 J/(°Ckg)) sphere is dropped from the space probe while is 75 m above the Lunar ground. If the sphere’s temperature increased by 0.11°C when it hits the ground, what percentage of the initial mechanical energy was absorbed as thermal energy by the aluminum sphere?

Answers

Answer:

13.759 % of the initial mechanical energy is lost as thermal energy.

Explanation:

By the First Law of Thermodynamics we know that increase in internal energy of the object ([tex]U[/tex]), in joules, is equal to the lost amount of the change in gravitational potential energy ([tex]U_{g}[/tex]), in joules:

[tex]\frac{x}{100} \cdot \Delta U_{g} = \Delta U[/tex] (1)

Where [tex]x[/tex] is the percentage of the energy loss, no unit.

By definition of the gravitational potential energy and internal energy, we expand this equation:

[tex]\frac{x\cdot m \cdot g \cdot h}{100} = m\cdot c\cdot \Delta T[/tex] (1b)

Where:

[tex]m[/tex] - Mass of the object, in kilograms.

[tex]g[/tex] - Gravitational acceleration, in meters per square second.

[tex]h[/tex] - Initial height of the object above the lunar ground, in meters.

[tex]c[/tex] - Specific heat of aluminium, in joules per degree Celsius-kilogram.

[tex]\Delta T[/tex] - Temperature increase due to collision, in degree Celsius.

If we know that [tex]m = 0.95\,kg[/tex], [tex]g = 9.807\,\frac{m}{s^{2}}[/tex], [tex]h = 75\,m[/tex], [tex]c = 920\,\frac{J}{kg\cdot ^{\circ}C}[/tex] and [tex]\Delta T = 0.11\,^{\circ}C[/tex], then the percentage of energy loss due to collision is:

[tex]x = \frac{100\cdot c\cdot \Delta T}{g\cdot h}[/tex]

[tex]x = \frac{100\cdot \left(920\,\frac{J}{kg\cdot ^{\circ}C} \right)\cdot (0.11\,^{\circ}C)}{\left(9.807\,\frac{m}{s^{2}} \right)\cdot (75\,m)}[/tex]

[tex]x = 13.759\,\%[/tex]

13.759 % of the initial mechanical energy is lost as thermal energy.

A ball is dropped from the roof of a 25-m-tall building. What is the velocity of the object when it touches the ground? Suppose the ball is a perfect golf ball and it bounces such that the ve locity as it leaves the ground has the same magnitude but the op posite direction as the velocity with which it reached the ground How high will the ball bounce? Now suppose instead that the ball bounces back to a height of 20 m. What was the velocity with which it left the ground?

Answers

Answer:

a)  [tex]h=25m[/tex]

b)  [tex]v=19.8m/sec[/tex]

Explanation:

From the question we are told that:

Height [tex]h=25m[/tex]

Bounce Height [tex]h'=20m[/tex]

Generally the Kinematic equation is mathematically given by

[tex]V=\sqrt{2gh}\\\\V=\sqrt{2*9.81*25}[/tex]

[tex]V=22.1m/sec[/tex]

Therefore Height

[tex]h=\frac{V^2}{2g}\\\\h=\frac{22.1^2}{2*9.81}[/tex]

[tex]h=25m[/tex]

b)

Generally the Kinematic equation is mathematically given by

[tex]v^2=2ah[/tex]

[tex]v^2=2*9.8*20[/tex]

[tex]v=\sqrt{2*9.8*20}[/tex]

[tex]v=19.8m/sec[/tex]

(9x10^2) + (1x10^2)
10x10^4
10x10^3
1x10^4
1x10^3

Answers

Answer:

10 x 10⁴

I hope it's helps you

Answer:

Yes

Explanation:

A golf club hits a 0.04551 kg golf ball off a golf tee. The club is in contact with the ball for 0.020 s, and the force applied by the club is 115 N. What is the speed of the ball as it leaves the tee

Answers

Answer:

v = 50.5 m/s

Explanation:

F = (m)(^v/^t)

115N = (0.04551kg)(v/(0.020s))

2,526.917161 m/s² = v/(0.020s)

v = 50.53834322 m/s

v = 50.5 m/s

(2) Why do spring balance shows wrong reading after they had been uses for a long time?​

Answers

This is because of continuous usage, the wire loses its elasticity and dose not regain it original dimension

Answer:

When a spring balance has been used for a long time, the spring in the balance fatigued and there is loss of strength of the spring. In such a case, the extension in the spring is more for a given load and hence the balance gives wrong readings.

balance the following equations: CUCO3+H2SO4- CUSO4+H2O+CO2​

Answers

Answer:

It is already balanced

Explanation:

It is already balanced

Which type of electromagnetic wave is deliberately used in some
circumstances to cause damage to living cells in the human body?
A. Infra-red
B. Gamma rays
C. Microwaves
D. Radio waves.

Answers

Gamma rays

used in radiotherapy

b) A force is represented in magnitude and direction as (6N, 250degrees. Find both the vertical and horizontal components of the force.​

Answers

Answer:

Explanation:

To find the horizontal component, the x component specifically, use the formula:

[tex]V_x=Fcos\theta[/tex] and for the vertical component, the y component, use the formula:

[tex]V_y=Fsin\theta[/tex]

where F is the magnitude of the force and theta is the angle in degrees.

For the x-component:

[tex]V_x=6cos250[/tex] so

[tex]V_x=-2.1[/tex] and depending upon whether this is a displacement vector or a velocity vector, the label would be meters/feet or m/s, respectively.

For the y-component:

[tex]V_y=6sin250[/tex] so

[tex]V_y=-5.6[/tex]

How do we aquire knowledge in science?

Answers

Answer:

By studying.

By paying attention to what the teacher is saying.

That's the way to receive knowledge.

HAVE A GREAT DAY

Explanation:

Please give me that little crown...

AND REMEMBER TO SMILE

What would be the acceleration in a body moving with uniform velocity and why?​

Answers

Explanation:

The derivative of a constant term is always 0. So the acceleration of the body would be zero. Hence, the acceleration of a body moving with uniform velocity will always be zero.

hope it helps you

A skipper on a boat notices wave crests passing his anchor chain every 5.6 s . He estimates the distance between wave crests to be 16 m . He also correctly estimates the speed of the waves. Find this speed.

Answers

Answer:

v = 2.85 m/s

Explanation:

Given that,

A skipper on a boat notices wave crests passing his anchor chain every 5.6 s.

The distance between wave crests to be 16 m.

We need to find the speed of the waves. The speed of a wave can be calculated by the formula as follows :

[tex]v=f\lambda\\\\v=\dfrac{\lambda}{T}\\\\v=\dfrac{16}{5.6}\\\\v=2.85\ m/s[/tex]

So, the speed of the wave is 2.85 m/s.

A simple machine has efficiency 90%. What does it mean? No machine has 109 efficiency,why?​

Answers

Answer:

Efficiency of a machine is 90% this means that the total energy produced to the machine only 90% is useful and given as a output.

Machines are not 100% efficient because some of the work done by a machine is used to overcome friction

A 210 Ohm resistor uses 9.28 W of power. How much current flows through the resistor? (unit=A)

Answers

Answer:

.21

Explanation:

i see everyone got it wrong so ill give you the answer, good luck :)

A man sees a deer in the road and slams on his brakes. If he is traveling at 45.2 m/s and comes to a stop in 2.74 s, what is his acceleration? O -6:02 m/s2 -0.0606 m/s2 -47.9 m/s2 0 -16.5 m/s2 ​

Answers

Answer:

16.50 m/s²

Explanation:

initial velocity(u)=45.2 m/s

final velocity(v)= 0 (it stops)

time taken(t)= 2.74 s

now,we have

acceleration(a)= (v-u)/t

= (0-45.2 m/s)/2.74s

= -45.2 m/s / 2.74s

= -16.50 m/s²

Answer:

[tex]\boxed {\boxed {\sf -16.5 \ m/s^2}}[/tex]

Explanation:

We are asked to find the acceleration of a man driving. Acceleration is the change in velocity over the change in time. Acceleration is calculated with the following formula.

[tex]a= \frac{v_f- v_i}{t}[/tex]

The driver's initial velocity is 45.2 meters per second. His final velocity is 0 meters per second because he came to a stop. He stopped in 2.74 seconds.

[tex]\bullet \ v_f= 0 \ m/s \\\bullet \ v_i= 45.2 \ m/s \\\bullet \ t= 2.74 \ s[/tex]

Substitute these values into the formula.

[tex]a= \frac{0 \ m/s - 45.2 \ m/s }{ 2.74 \ s}[/tex]

Solve the numerator by subtracting.

[tex]a= \frac{- 45.2 \ m/s }{ 2.74 \ s}[/tex]

[tex]a= -16.49635036 \ m/s^2[/tex]

The original measurements of velocity and time have 3 significant figures, so our answer must have the same. For the number we calculated, that is the tenths place. The 9 in the hundredth place tells us to round the 4 in the tenths place up to a 5.

[tex]a \approx -16.5 \ m/s^2[/tex]

The acceleration is approximately -16.5 meters per second squared. The acceleration is negative because the man slowed down and came to a stop.

Define derived unit with example​

Answers

Answer:

A derived unit is a SI unit of measurement comprised of a combination of the seven base units. Like SI unit of force is the derived unit, newton or N where N=s21×m×kg. There are some commonly used derived units which includes: 1. Pressure = AreaForce=m2N.

Explanation:

The T-chart compares the average temperature and humidity of two different environments. Which of the following correctly labels the environments?

a t-chart with one column labeled A listing: High humidity: 70%, Temperature Range: 2 degrees Celsius (35 degrees Fahrenheit) in the winter to 24 degrees Celsius (75 degrees Fahrenheit); and another column labeled B listing: Low humidity (13-15%), Temperature Range: -18 degrees Celsius (-1 degrees Fahrenheit) to 49 degrees Celsius (120 degrees Fahrenheit)

A is a desert, and B is a tundra.
A is a grassland, and B is a desert.
A is a tundra, and B is a rainforest.
A is a tundra, and B is a swamp.

Answers

Answer:

A turndra B rainforest

Explanation:

What benefits does using this model have over preforming the modeled procedure with physical materials?


Please help!!

Answers

Explanation:

Advantages of physical models include accuracy, safety, visualization, education, and trying things out that would be impossible in the real world due to safety, cost, or practical concerns. You can visualize things that are extremely tiny, happened millions of years ago, or that otherwise can't be viewed directly.

out of solid and liquid which has more effect on gravitation​

Answers

Answer:

The effect of gravitation is more in liquid than on solid because inter molecular force of attraction is less in liquid and it is weak than that of solid. ... Whereas in solid the molecule are densely packed together an the inter molecular forces are constantly acting upon one another, this results in higher forces.

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