Ask question

Ask question

All categories

2 years ago

14

Một dây dẫn mảnh được uốn thành một cung tròn bán kính 10cm, góc ở tâm bằng 1200, đặt trong không khí. Trong dây dẫn có dòng điệ

n cường độ 30A chạy qua. Độ lớn của cảm ứng từ tại tâm của cung tròn là bao nhiêu ?

1 answer:

olga2289 [7]2 years ago

7 0

Answer:

Diana and that

Explanation:

muyayyano

You might be interested in

When approaching an intersection, bridge, or railroad crossing, you should never drive (pass on the left half of the roadway whe

e-lub [12.9K]

You should not go into the left side of the roadway when within 100 feet of the crossing. Moreover, you should also turn on your turn signal when within 100 of a turn. These precautions prevent accidents as it makes clear to other drivers what your intentions are and drivers making turns are not endangered.

8 0

3 years ago

The wavelength of red helium-neon laser light in air is 632.8 nm.(a) What is its frequency? Hz(b) What is its wavelength in glas

vekshin1

<h2>Answers:</h2>

The speed of a wave is given by:

$v=f.\lambda$ (1)

Where $f$ is the frequency and $\lambda$ the wavelength.

In the case of light, its speed is:

$c=f.\lambda$ (2)

On the other hand, the described situation is known as Refraction, a phenomenon in which the light changes its direction when passing through a medium with a refractive index different from the other medium.

In this context, the Refractive index $n$ is a number that describes how fast light propagates through a medium or material, and is defined as the relation between the speed of light in vacuum ( $c=3(10)^{8}m/s$ ) and the speed of light $v$ in the second medium:

$n=\frac{c}{v}$ (3)

In addition, as the light changes its direction, its wavelength changes as well:

$n=\frac{\lambda_{air}}{\lambda_{glass}}$ (4)

Knowing this, let's begin with the answers:

<h2>a) Frequency</h2>

From equation (2) we can find $f$ :

$f=\frac{c}{\lambda}$ (5)

Knowing that $1nm=(10)^{-9}m$ :

$f=\frac{3(10)^{8}m/s}{632.8(10)^{-9}m}$

$f=4.74(10)^{14}Hz}$ (6) >>>Frequency of the helium-neon laser light

<h2>b) Wavelength in glass</h2>

We already know the wavelength of the light in air $\lambda_{air}$ and the index of refraction of the glass.

So, we only have to find the wavelength in glass $\lambda_{glass}$ from equation (4):

$\lambda_{glass}=\frac{\lambda_{air}}{n}$

$\lambda_{glass}=\frac{632.8(10)^{-9}m}{1.48}$

$\lambda_{glass}=427(10)^{-9}m=427nm$ (7) >>>Wavelength of the helium-neon laser light in glass

<h2>c) Speed in glass</h2>

From equation (3) we can find the speed $v$ of this light in glass:

$v=\frac{c}{n}$

$v=\frac{3(10)^{8}m/s}{1.48}$

$v=2.027(10)^{8}m/s$ (8) >>>Speed of the helium-neon laser light in glass

7 0

3 years ago

to start an avalanche on a mountain slope, an artillery shell is fired with an initial velocity of 290 m/s at 53.0° above the ho

kap26 [50]

So this is easy to calculate when you split the velocity into x and y components. The x component is going to equal cos(53) * 290 and the y component is going to equal sin(53)*290.

The x location therefore is 290*cos(53)*35 = 6108.4m

The y location needs to factor in the downwards acceleration of gravity too, which is 9.81m/s^2. We need the equation dist. = V initial*time + 0.5*acceleration*time^2.

This gives us d=290*sin(53)*35 + (0.5*-9.81*35^2)=2097.5m

So your (x,y) coordinates equals (6108.4, 2097.5)

5 0

3 years ago

When a object is at rest, what is it’s speed??

nadya68 [22]

Answer:

0 (there is no speed)

Explanation:

If an object is at rest, it is not moving, and it doesn't have a speed, so the speed is zero.

3 0

3 years ago

Read 2 more answers

A. Describe the photoelectric effect and explain why it could not be explained by Newtonian physics.

Leno4ka [110]

Explanation:

(a)

The photoelectric effect is the phenomenon in which the light of the particular frequency incidents on the material. Then the emission of the electrons from the surface of the material occurs.

This phenomenon could not be explained by Newtonian physics.

In Newtonian physics, the energy is not discrete. In quantum mechanics, the energy is discrete. This is the main why the photoelectric effect could not be explained by Newtonian physics.

(b)

Light consists of photons. The photon is a packet of energy. It is also called quanta. The energies of the photons are quantized.

When a photon strikes on the surface of metal then the energy of photon is absorbed by an electron in the metal so that it may eject from the surface. This phenomenon is called the photoelectric effect.

(c)

In quantum mechanics, wave-particle duality concept is used to explain the wave-particle nature of the light. Light behaves as particle as well as wave. It shows both nature. The photoelectric phenomenon shows the particle nature of the light. It acts as a particle when it hits the surface of the metal.

In line spectra, the electron is excited to an energy level. In this case energy is transferred from photon to electron. There is a collision between photon and electron. The change in momentum will occur. It shows the particle nature of the light.

3 0

3 years ago

Read 2 more answers