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3 years ago

6

g Calculate the maximum wavelength of light that will cause the photoelectric effect for potassium. Potassium has work function

2.29 eV = 3.67 x 10–19 J.

1 answer:

Ivahew [28]3 years ago

4 0

Answer:

λ = 5.4196 10⁻⁷m, λ = 541.96 nm this is green ligh

Explanation:

The photoelectric effect was explained by Eintein assuming that the light was made up of particles called photons and these collided with the electrons taking them out of the material.

K = h f -Ф

where K is the kinetic energy of the ejected electrons, hf is the energy of the light quanta and fi is the work function of the material.

The speed of light is related to wavelength and frequency

c = λ / f

f = c /λ

we substitute

K = h c / λ - Φ

for the case that they ask us the kinetic energy of the electons is zero (K = 0)

h c / λ = Ф

λ = h c / Ф

we calculate

λ = 6.63 10⁻³⁴ 3 10⁸ / 3.67 10⁻¹⁸

λ = 5.4196 10⁻⁷m

let's take nm

lam = 541.96 nm

this is green light

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During most of its lifetime, s star maintains an equilibrium size in which the inward force of gravity on each atom is balanced

frez [133]

Answer:

$r_f=137493m$

$v=8638940m/s$

Explanation:

During this process the mass $M=2\times10^{30}Kg$ will be considered constant. We start from a radius $r_i=7\times10^8m$ and a period $T_i=30\ days=(30)(24)(60)(60)s=2592000s$ . The final period is $T_f=0.1s$ .

Angular momentum <em>L</em> is conserved in this process. We can use the formula $L=I\omega$ , where I is the momentum of inertia (which for a solid sphere is $I=\frac{2mr^2}{5}$ ) and $\omega=\frac{2\pi }{T}$ is the angular velocity, so we can write the star's angular momentum as:

$L=I\omega=\frac{2mr^2}{5}\frac{2\pi }{T}=\frac{4\pi mr^2 }{5T}$

Since $L_f=L_i$ we have:

$\frac{4\pi mr_f^2 }{5T_f}=\frac{4\pi mr_i^2 }{5T_i}$

Which can be simplified as:

$\frac{r_f^2 }{T_f}=\frac{r_i^2 }{T_i}$

Which means:

$r_f=\sqrt{\frac{r_i^2 T_f}{T_i}}=r_i \sqrt{\frac{T_f}{T_i}}$

Which for our values is:

$r_f=r_i \sqrt{\frac{T_f}{T_i}}=(7\times10^8m) \sqrt{\frac{0.1s}{2592000s}}=137493m$

And we calculate the speed of a point on the equator by dividing the final circumference over the final period:

$v=\frac{C_f}{T_f}=\frac{2\pi r_f}{T_f}=\frac{2\pi (137493m)}{(0.1s)}=8638940m/s$

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4 years ago

A4.0 kg object is moving with speed 2.0 m/s. A 1.0 kg object is moving with speed 4.0 m/s. Both objects encounter the same const

Evgesh-ka [11]

Answer:

Both objects travel the same distance.

(c) is correct option

Explanation:

Given that,

Mass of first object = 4.0 kg

Speed of first object = 2.0 m/s

Mass of second object = 1.0 kg

Speed of second object = 4.0 m/s

We need to calculate the stopping distance

For first particle

Using equation of motion

$v^2=u^2+2as$

Where, v = final velocity

u = initial velocity

s = distance

Put the value in the equation

$0= u^2-2as_{1}$

$s_{1}=\dfrac{u^2}{2a}$ ....(I)

Using newton law

$a=\dfrac{F}{m}$

Now, put the value of a in equation (I)

$s_{1}=\dfrac{8}{F}$

Now, For second object

Using equation of motion

$v^2=u^2+2as$

Put the value in the equation

$0= u^2-2as_{2}$

$s_{2}=\dfrac{u^2}{2a}$ ....(I)

Using newton law

$F = ma$

$a=\dfrac{F}{m}$

Now, put the value of a in equation (I)

$s_{2}=\dfrac{8}{F}$

Hence, Both objects travel the same distance.

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earnstyle [38]

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Explanation:

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Slav-nsk [51]

Answer:

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Explanation:

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$v_{rms}$ = RMS Speed

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T = The temperature

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n = The number of moles

V = The volume

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When a wire is made smaller, the resistance increases. Which happens to the electric current?

Lelu [443]

When a wire is made shorter, the resistance decreases.

When a wire is made thinner, the resistance increases.

8 0

4 years ago