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3 years ago

A 193nm-wavelength UV laser for eye surgery emits a 0.500mJ pulse. (a) How many photons does the light pulse contain?

Physics

2 answers:

Law Incorporation [45]3 years ago

6 0

Answer:

The number of photons is 4.8x10^14

Explanation:

The frequency of wave is equal to:

$f=\frac{c}{l}$

where c is the speed of light, l is the wavelength of wave. Replacing values:

$f=\frac{3x10^{8} }{193x10^{9} } =1.5x10^{15} Hz$

The energy of the proton is:

$E=hf$

where h is the Planck´s constant. Replacing

$E=6.626x10^{-34}*1.5x10^{5}=1.03x10^{-18} J$

The number of photons is:

$n=\frac{E1}{E}$

where E1 is the energy of photon. Replacing:

$n=\frac{0.5x10^{-3} }{1.03x10^{-18} }=4.8x10^{14}$

Marrrta [24]3 years ago

4 0

Using the equation E = hc/λ we can find out how much energy a single photon of wavelength 193 nm has. E = Planck Constant * Speed of Light/193 nm

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Ethan made a diagram to compare examples of the first and second laws of thermodynamics. What belongs in the areas marked X and

bazaltina [42]

Answer:

The answer is X: Thermal energy is converted to light energy

Y: A cold spoon placed in hot liquid gets warmer

Explanation:

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4 years ago

A car is traveling at a speed of 10m/s. A 0.5kg clump of mudis

CaHeK987 [17]

Answer:B

Explanation:

Given

speed of car $v=10 m/s$

mass of clump $m=0.5 kg$

Radius of car tire $r=0.2 m$

Since the tire is rotating about axle so a centripetal force is acting constantly on each particle towards the center of tire.

Centripetal force is given by

$F_c=\frac{mv^2}{r}$

where $m=mass\ of\ element$

$v=speed$

$r=distance\ from\ center$

$F_c=\frac{0.5\times 10^2}{0.2}$

$F_c=250\ N$ (inward)

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3 years ago

A stretched string has a mass per unit length of 5.40 g/cm and a tension of 17.5 N. A sinusoidal wave on this string has an ampl

kondaur [170]

Answer:

Part a)

$y_m = 0.157 mm$

part b)

$k = 101.8 rad/m$

Part c)

$\omega = 579.3 rad/s$

Part d)

here since wave is moving in negative direction so the sign of $\omega$ must be positive

Explanation:

As we know that the speed of wave in string is given by

$v = \sqrt{\frac{T}{m/L}}$

so we have

$T = 17.5 N$

$m/L = 5.4 g/cm = 0.54 kg/m$

now we have

$v = \sqrt{\frac{17.5}{0.54}}$

$v = 5.69 m/s$

now we have

Part a)

$y_m$ = amplitude of wave

$y_m = 0.157 mm$

part b)

$k = \frac{\omega}{v}$

here we know that

$\omega = 2\pi f$

$\omega = 2\pi(92.2) = 579.3 rad/s$

so we have

$k = \frac{579.3}{5.69}$

$k = 101.8 rad/m$

Part c)

$\omega = 579.3 rad/s$

Part d)

here since wave is moving in negative direction so the sign of $\omega$ must be positive

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3 years ago

Tell whether each element has a high or low electronegativity : bromine, chlorine, potassium, lithium

finlep [7]

Answer:

Bromine-2.8 high

Chlorine-3.0 high

Potassium-0.8 low

Lithium-1.0 low

Explanation:

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3 years ago

Both the lens and the cornea of the eye have a primary function of

3241004551 [841]

Answer: B. bending light

Explanation:

The phenomenom of vision in human eye is thanks to refraction (when light changes its direction as it passes through one medium to another), and this is what the cornea and the lens do.

When the ray of light encounters the eye, the first thing it finds is the cornea, which bends this ray and begins to form an image, then light passes through the pupil, which is in charge of regulating the amount of light that enters in the eye.

After light travels through pupil it passes through the lens, where the rays of light change the direction again in order to focus the formed image on the retina.

At this point it is important to note the formed image is downward, then the retina transforms light into electrical impulses that are sent to the brain through the optic nerve and finally the brain interprets these messages, and forms a right upward image.

In the image attached these parts can be seen.

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3 years ago