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3 years ago

Question 9 of 10

Physics

2 answers:

Temka [501]3 years ago

7 0

Answer:

Probably Answer A

Explanation:

We have to define our reference frame

Light moving into a medium of higher index of refraction will slow down

So Answers B and D are eliminated.

If the reference frame is perpendicular to the surface as is typical in refraction problems, the incidence angle decreases, Answer A

If the reference frame is parallel to the surface, then the angle increases, Answer C

fomenos3 years ago

5 0

Answer:

v = C / n light slows entering a medium of higher index of refraction

ni sin theta i = nr sin theta r Snell's Law where i refers to incidence and r refers to refraction

sin theta r = (ni / nr) sin theta i

So if the index of refraction is greater than the angle of incidence then the light ray would be refracted towards the normal

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A non uniform rod has mass

Doss [256]

Answer:

$r_{cm} = L/3$

Explanation:

Mass: M, Length: L.

$\sigma (x) = b(L-x)$

The formula that gives center of mass is

$\vec{r}_{cm} = \frac{m_1\vec{r}_1 + m_2\vec{r}_2 + ...}{m_1 + m_2 + ...} = \frac{\Sigma m_i \vec{r}_i}{\Sigma m_i}$

In the case of a non-uniform mass density, this formula converts to

$\vec{r}_{cm} = \frac{\int\limits^L_0 {x\sigma(x)} \, dx }{\int\limits^L_0 {\sigma(x)} \, dx }$

where the denominator is the total mass and the nominator is the mass times position of each point on the rod.

We have to integrate the mass density over the total rod in order to find the total mass. Likewise, we have to integrate the center of mass of each point (xσ(x)) over the total rod. And if we divide the integrated center of mass to the total mass, we find the center of mass of the rod:

$\vec{r}_{cm} = \frac{\int\limits^L_0 {x\sigma(x)} \, dx }{\int\limits^L_0 {\sigma(x)} \, dx } = \frac{\int\limits^L_0 {xb(L-x)} \, dx }{\int\limits^L_0 {b(L-x)} \, dx } = \frac{b\int\limits^L_0{(xL - x^2)} \, dx }{b\int\limits^L_0 {(L-x)} \, dx } = \frac{\frac{x^2L}{2} - \frac{x^3}{3}}{Lx - \frac{x^2}{2}}\left \{ {{x=L} \atop {x=0}} \right.$

Here x's are cancelled. Otherwise, the denominator would be zero.

$r_{cm} = \frac{\frac{xL}{2}-\frac{x^2}{3}}{L-\frac{x}{2}}\left \{ {{x=L} \atop {x=0}} \right. = \frac{\frac{L^2}{2}-\frac{L^2}{3}}{L-\frac{L}{2}} = \frac{\frac{L^2}{6}}{\frac{L}{2}} = \frac{L}{3}$

8 0

3 years ago

Coiling wire around an iron core and applying an electric current through the wire creates a temporary magnet called an electrom

Serggg [28]

Answer:

C) Use a battery with more voltage.

Explanation:

The equation for the magnetic field around a coil is given by,

B = μ₀NI

where,

B = Magnetic flux density

μ₀ = permeability

N = number of turns per meter

I = Current in the wire

So when using a higher voltage battery, more current passes through the battery as resistance of the wire remains the same.

5 0

3 years ago

Read 2 more answers

An electron is accelerated from rest by a potential difference of 412 V. It then enters a uniform magnetic field of magnitude 18

Salsk061 [2.6K]

Explanation:

Given that,

Potential difference, V = 412 V

Magnitude of magnetic field, B = 188 mT

(a) The potential energy of electron is balanced by its kinetic energy as :

$eV=\dfrac{1}{2}mv^2$

v is speed of the electron

$v=\sqrt{\dfrac{2eV}{m}} \\\\v=\sqrt{\dfrac{2\times 1.6\times 10^{-19}\times 412}{9.1\times 10^{-31}}} \\\\v=1.2\times 10^7\ m/s$

(b) When the charged particle moves in magnetic field, it will move in circular path. The radius of the circular path is given by :

$r=\dfrac{mv}{eB}\\\\r=\dfrac{9.1\times 10^{-31}\times 1.2\times 10^7}{1.6\times 10^{-19}\times 188\times 10^{-3}}\\\\r=3.63\times 10^{-4}\ m$

Hence, this is the required solution.

7 0

3 years ago

I need help pls help me

chubhunter [2.5K]

Answer:

Explanation:

I am assuming that you got to go up to Zak as his editor and tell him in his face if he is doing the work correctly. Dont trust me though, cause C also looks plausible

6 0

3 years ago

Why can't speed ratio ever equal mechanical advantage?

OLga [1]

Efficiency of a simple machine is the ratio of mechanical advantage and speed ratio.

If mechanical advantage = speed ratio then efficiency = 1
Which is impossible for a practical machine due to presence of frictional force which wastes some energy and thus lowers the output

6 0

3 years ago