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4 years ago

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

2 answers:

8 0

a) This effect results in emission of electrons out of the lighted area of metals. According to Newtonian mechanics, energy is continuous (may take any value), but photoelectric effect implies using discrete energy ideas.

b) 'Quantum' means 'part' and is being used in physics fir describing light. Light consists of separate particles. This theory fits well what we observe in photoelectric effect: one light particle smashes one electron and it leaves surface of a metal.

c) Quantum mechanics describes everything as wave and particle at a time and it is called dualism. Electrons have separate quantified energetic levels and they go up/down consuming/emitting light waves. The lines in the spectrum fit these energetic levels.

Leno4ka [110]4 years ago

3 0

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.

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Stels [109]

A hologram is a physical structure that diffracts light into an image. The term ‘hologram’ can refer to both the encoded material and the resulting image. A holographic image can be seen by looking into an illuminated holographic print or by shining a laser through a hologram and projecting the image onto a screen. Hope this helps! Oh and here's a good source to use just don't forget to credit the sources you use.

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7 0

4 years ago

A ball of mass m= 450.0 g traveling at a speed of 8.00 m/s impacts a vertical wall at an angle of θi =45.00 below the horizontal

Mkey [24]

Answer:

F = 20.4 i ^

Explanation:

This exercise can be solved using the ratio of momentum and amount of movement.

I = F t = Dp

Since force and amount of movement are vector quantities, each axis must be worked separately.

X axis

Let's look for speed

cos 45 = vₓ / v

vₓ = v cos 45

vₓ = 8 cos 45

vₓ = 5,657 m / s

We write the moment

Before the crash p₀ = m vₓ

After the shock $p_{f}$ = -m vₓ

The variation of the moment Δp = mvₓ - (-mvₓ) = 2 m vₓ

The impulse on the x axis Fₓ t = Δp

Fₓ = 2 m vₓ / t

Fx = 2 0.450 5.657 / 0.250

Fx = 20.4 N

We perform the same calculation on the y axis

sin 45 = vy / v

vy = v sin 45

vy = 8 sin 45

vy = 5,657 m / s

We calculate the initial momentum po = m $v_{y}$

Final moment $p_{f}$ = m $v_{y}$

Variations moment Δp = m $v_{y}$ - m $v_{y}$ = 0

Force in the Y-axis $F_{y}$ = 0

Therefore the total force is

F = fx i ^ + Fyj ^

F = Fx i ^

F = 20.4 i ^

3 0

4 years ago

A standard steel pipe (D = 3.81 in.; d = 3.24 in.) supports a concentrated load of P = 930 lb. The span length of the cantilever

Maurinko [17]

Answer:

a) τmax = 586.78 P.S.I.

b) σmax = 15942.23 P.S.I

Explanation:

D = 3.81 in

d = 3.24 in

P = 930 lb

L = 3.7 ft = 44.4 in

a) The maximum horizontal shear stress can be obtained as follows

τ = V*Q / (t*I)

where

V = P = 930 lb

Q = (2/3)*(R³- r³) = (1/12)*(D³- d³) = (1/12)*((3.81 in)³- (3.24 in)³)

⇒ Q = 1.7745 in³

t = D - d = 3.81 in - 3.24 in = 0.57 in

I = (π/64)*(D⁴-d⁴) = (π/64)*((3.81 in)⁴- (3.24 in)⁴) = 4.9341 in⁴

then

τ = (930 lb)*(1.7745 in³) / (0.57 in*4.9341 in⁴)

⇒ τmax = 586.78 P.S.I.

b) We can apply the following equation in order to get the maximum tension bending stress in the pipe

σmax = Mmax *y / I

where

Mmax = P*L = 930 lb*44.4 in = 41292 lb-in

y = D/2 = 3.81 in /2 = 1.905 in

I = 4.9341 in⁴

then

σmax = (41292 lb-in)*(1.905 in) / (4.9341 in⁴) = 15942.23 P.S.I

6 0

4 years ago

⚠️ PLEASE HELP ⚠️

Svetllana [295]

Answer:

-79.6

-80

-81.2

Explanation:

5 0

4 years ago

Read 2 more answers

If you drop an object from rest, the distance it falls is given by (1/2)at2, where a is the acceleration of the object and t is

klio [65]

If,

$d \: = \: \frac{1}{2} a {t}^{2}$

then, with 3x time t, (suppose, new distance is h)

$h \: = \: \frac{1}{2} a {(3t)}^{2}$

$= \frac{1}{2} a9 {t}^{2}$

$= 9 \: \frac{1}{2} a{t}^{2}$

$= 9d$

Therefore, new distance h will be 9 times bigger than distance d.

answer: c

7 0

3 years ago