What is 0.94kg divided by 2.4n

The power output of a laser is measured by its wattage, the number of joules of energy it radiates per second (1 W = 1 J s-1). A

viva [34]

Explanation:

It is given that,

Wavelength of red light, $\lambda=676.4\ nm=676.4\times 10^{-9}\ m$

Power of the laser, $P=300\ mW=0.3\ W$

(a) The energy carried by each photon is given by :

$E=\dfrac{hc}{\lambda}$

$E=\dfrac{6.63\times 10^{-34}\times 3\times 10^8}{676.4\times 10^{-9}}$

$E=2.94\times 10^{-19}\ J$

(b) Let n is the number of photons emitted by the laser per second. It can be calculated as :

$n=\dfrac{Power}{Energy\ of\ one\ photon}$

$n=\dfrac{0.3}{2.94\times 10^{-19}}$

$n=1.02\times 10^{18}\ photon/s$

Hence, this is the required solution.

7 0

3 years ago

The n = 2 to n = 6 transition in the bohr hydrogen atom corresponds to the ________ of a photon with a wavelength of ________ nm

Colt1911 [192]

The energy levels of the hydrogen atom are quantized and their energy is given by the approximated formula
$E=- \frac{13.6}{n^2} [eV]$
where n is the number of the level.

In the transition from n=2 to n=6, the variation of energy is
$\Delta E=E(n=6)-E(n=2)=-13.6 ( \frac{1}{6^2}- \frac{1}{2^2} )[eV]=3.02 eV$
Since this variation is positive, it means that the system has gained energy, so it must have absorbed a photon.

The energy of photon absorbed is equal to this $\Delta E$ . Converting it into Joule,
$\Delta E=3.02 eV=4.84 \cdot 10^{-19}J$
The energy of the photon is
$E=hf$
where h is the Planck constant while f is its frequency. Writing $\Delta E=hf$ , we can write the frequency f of the photon:
$f= \frac{\Delta E}{h}= \frac{4.84 \cdot 10^{-19}J}{6.63 \cdot 10^{-34}m^2 kg/s}=7.29 \cdot 10^{14}Hz$

The photon travels at the speed of light, $c=3 \cdot 10^8 m/s$ , so its wavelength is
$\lambda = \frac{c}{f}= \frac{3 \cdot 10^8 m/s}{7.29 \cdot 10^{14}Hz}=4.11 \cdot 10^{-7}m=411 nm$

So, the initial sentence can be completed as:
The n = 2 to n = 6 transition in the bohr hydrogen atom corresponds to the "absorption" of a photon with a wavelength of "411" nm.

4 0

4 years ago

Read 2 more answers

The hour and minute hands of a tower clock like Big Ben in London are 2.79 m and 4.44 m long and have masses of 58.2 kg and 90 k

LuckyWell [14K]

Answer: 895.85 x 10^-6 J or 8.96 x 10^-4 J

Explanation:

Angular kinetic energy E in Joules

E = ½Iw^2

W is angular velocity in radians/sec

1 radian/sec = 9.55 rev/min

I is moment of inertia in kgm^2

I = cMR^2

M is mass (kg), R is radius (meters)

c = 1/3 for a rod around its end, R = length

For minute hand

I = (1/3)(90)(4.44)^2 = 0.33 x 90 x 19.7136 = 585.49

w= 1 rev/hour = 1 rev/3600sec = 2pi/ 3600 = pi/1800 rad/s

KE = 1/2(1/3)(90)(4.44)^2(pi/1800)^2 = 0.5 x 0.33 x 90 x 19.7136 x 3.05 x 10^-6

KE = 0.00089 J

For hour hand

I = (1/3)(58.2)(2.79)^2 = 0.33 x 58.2 x 2.79^2 = 149.5

w = 1 rev/12hour = 1 rev/(12x3600sec) = 2pi/ 12x3600 = pi/21600 rad/s

KE = 1/2(1/3)(90)(4.44)^2(pi/21600)^2 = 0.5 x 0.33 x 90 x 19.7136 x 2.12 x 10^-8

KE = 5.85 x 10^-6 J

Therefore total kinetic energy = 895.85 x 10^-6 J

4 0

4 years ago

A car is towing a boat on a trailer. The driver starts from rest and accelerates to a velocity of +16.7 m/s in a time of 20.7 s.

frutty [35]

Answer:

F = 479.21 N

Explanation:

given,

initial velocity = 0 m/s

final velocity = 16.7 m/s

time taken = 20.7 s

combined mass of the boat and trailer = 594 kg

tension in the hitch = ?

using equation of motion

v = u + a t

16.7 = 0 + a × 20.7

a = 0.807 m/s²

Force = mass × acceleration

F = 594 × 0.807

F = 479.21 N

Hence, the tension in the hitch that connects the trailer to the car is F = 479.21 N

7 0

3 years ago

How do you do this?Or what are the formulus

LuckyWell [14K]

You got the formulas on the sheet on the top :) So just use those, exchanging v (as in velocity, expressed in m/s) and the d (in meters) and t (in seconds). Hope you will manage it.

4 0

3 years ago