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2 years ago

A microwave oven operates at 3.00 ghz . what is the wavelength of the radiation produced by this appliance?

1 answer:

3 0

Thank you for posting your question here at brainly. Below is the solution:

Speed of light is 300,000,000 meters per second or 3E8 m/s

Wavelength = Speed of light divided by the frequency = c / f 

3 GHz = 3 GigaHertz = 3E9 Hertz = 3,000,000,000 Hz 

L = (300,000,000 m/s) / (3,000,000,000 Hz) = 0.1 meter = 10 centimeters

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Joan and Mike's teacher show them a picture of an atom and ask them to identify it using the periodic table. Joan says the atom

zhenek [66]

Well we can't see the picture that the teacher has, and we have to figure out what's in the picture from some clues in the answer choices. The picture seems to show an atom with 3 protons and 3 neutrons in the nucleus, and 3 electrons whizzing around the nucleus.

If that's what's in the picture, then Mike is correct (first choice), because the atomic number shows the number of protons in all atoms. There are 3 protons and the atomic number of lithium is 3.

Second choice . . . False, because electrons are not involved in the atomic mass.

Third and fourth choices . . . both false; sadly, Joan is woefully unclear on the concepts.

3 0

2 years ago

B⃗ is kept constant but the coil is rotated so that the magnetic field, B⃗ , is now in the plane of the coil. How will the magne

s344n2d4d5 [400]

Answer:

The flux decreases because the angle between B⃗ and the coil's axis changes.

Explanation:

The flux through the coil is given by a dot product, between the magnetic field and the vector representing the area of the coil.

$\Phi = \vec{B}\cdot \vec{S} = BScos(\theta)$

The latter vector has direction perpendicular to the plane in which the area of the coil is, and magnitude equal to the area of the coil. As in the attached image, the vector S is the vector respresenting the area of the coil.

Therefore, the flux will be maximum when the vector S is in the same direction as B, and will be zero when they are perpendicular.

Now, if the coil is rotated so that the magnetic field is in the plane of the coil then, the vectors S and B are perpendicualr, and there will not be net magnetic flux, that is, the flux will decrease.

3 0

2 years ago

Read 2 more answers

A car with speed v and an identical car with speed 2v both travel the same circular section of an unbanked road. If the friction

yawa3891 [41]

Answer:

$F'=\dfrac{F}{4}$

Explanation:

Let m is the mass of both cars. The first car is moving with speed v and the other car is moving with speed 2v. The only force acting on both cars is the centripetal force.

For faster car on the road,

$F=\dfrac{mv^2}{r}$

v = 2v

$F=\dfrac{m(2v)^2}{r}$

$F=4\dfrac{m(v)^2}{r}$ ..........(1)

For the slower car on the road,

$F'=\dfrac{mv^2}{r}$ ............(2)

Equation (1) becomes,

$F=4F'$

$F'=\dfrac{F}{4}$

So, the frictional force required to keep the slower car on the road without skidding is one fourth of the faster car.

8 0

2 years ago

A hot (70°C) lump of metal has a mass of 250 g and a specific heat of 0.25 cal/g⋅°C. John drops the metal into a 500-g calorimet

Gnom [1K]

Answer:

d. 37 °C

Explanation:

$m_{m}$ = mass of lump of metal = 250 g

$c_{m}$ = specific heat of lump of metal = 0.25 cal/g°C

$T_{mi}$ = Initial temperature of lump of metal = 70 °C

$m_{w}$ = mass of water = 75 g

$c_{w}$ = specific heat of water = 1 cal/g°C

$T_{wi}$ = Initial temperature of water = 20 °C

$m_{c}$ = mass of calorimeter = 500 g

$c_{c}$ = specific heat of calorimeter = 0.10 cal/g°C

$T_{ci}$ = Initial temperature of calorimeter = 20 °C

$T_{f}$ = Final equilibrium temperature

Using conservation of heat

Heat lost by lump of metal = heat gained by water + heat gained by calorimeter

$m_{m} c_{m} (T_{mi} - T_{f}) = m_{w} c_{w} (T_{f} - T_{wi}) + m_{c} c_{c} (T_{f} - T_{ci}) \\(250) (0.25) (70 - T_{f} ) = (75) (1) (T_{f} - 20) + (500) (0.10) (T_{f} - 20)\\T_{f} = 37 C$

6 0

2 years ago

A proton initially moves left to right along the x-axis at a speed of 2.00 x 103 m/s. It moves into an uniform electric field, w

FinnZ [79.3K]

Answer:

E = 1.04*10⁻¹ N/C

Explanation:

Assuming no other forces acting on the proton than the electric field, as this is uniform, we can calculate the acceleration of the proton, with the following kinematic equation:

$vf^{2} -vo^{2} = 2*a*x$

As the proton is coming at rest after travelling 0.200 m to the right, vf = 0, and x = 0.200 m.

Replacing this values in the equation above, we can solve for a, as follows:

$a = \frac{vo^{2}*mp}{2*x} = \frac{(2.00e3m/s)^{2}}{2*0.2m} = 1e7 m/s2$

According to Newton´s 2nd Law, and applying the definition of an electric field, we can say the following:

F = mp*a = q*E

For a proton, we have the following values:

mp = 1.67*10⁻²⁷ kg

q = e = 1.6*10⁻¹⁹ C

So, we can solve for E (in magnitude) , as follows:

$E = \frac{mp*a}{e} =\frac{1.67e-27kg*1e7m/s2}{1.6e-19C} = 1.04e-1 N/C$

⇒ E = 1.04*10⁻¹ N/C

5 0

2 years ago