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Ann [662]
3 years ago
11

Heated lithium atoms emit photons of light with an energy of 2.961 × 10−19 J. Calculate the frequency and wavelength of one of t

hese photons. What is the total energy in 1 mole of these photons? What is the color of the emitted light?
Physics
1 answer:
tatiyna3 years ago
6 0

Answer:

4.5 x 10¹⁴ Hz

666.7 nm

1.8 x 10⁵ J

The color of the emitted light is red

Explanation:

E = energy of photons of light = 2.961 x 10⁻¹⁹ J

f = frequency of the photon

Energy of photons is given as

E = h f

2.961 x 10⁻¹⁹ = (6.63 x 10⁻³⁴) f

f = 4.5 x 10¹⁴ Hz

c = speed of light = 3 x 10⁸ m/s

λ = wavelength of photon

Using the equation

c = f λ

3 x 10⁸ = (4.5 x 10¹⁴) λ

λ = 0.6667 x 10⁻⁶ m

λ = 666.7 x 10⁻⁹ m

λ = 666.7 nm

n = number of photons in 1 mole = 6.023 x 10²³

U = energy of 1 mole of photons

Energy of 1 mole of photons is given as

U = n E

U = (6.023 x 10²³) (2.961 x 10⁻¹⁹)

U = 1.8 x 10⁵ J

The color of the emitted light is red

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Pressure and volume changes at a constant temperature can be calculated using
V125BC [204]

Answer:

Option A, Boyle's law

Explanation:

The complete question is

Pressure and volume changes at a constant temperature can be calculated using

a. Boyle's law. c. Kelvin's law.

b. Charles's law. d. Dalton's law.

Solution

In Boyle’s law, the gas is assumed to be ideal gas and at constant  temperature. With these two conditions fixed, Boyle’s established that volume of gas varies inversely with the absolute pressure.  

The basic mathematical representation of this phenomenon is as follows -  

P \alpha \frac{1}{V}

OR

P = \frac{k}{V} \\PV = k

Where P is the pressure of ideal gas, V is the volume and k is the constant of proportionality.

Hence, option A is correct

3 0
3 years ago
When this current is closed which way does the current flow
Anastaziya [24]
Well, Godess, that's not a simple question, and it doesn't have
a simple answer.

When the switch is closed . . .

"Conventional current" flows out of the ' + ' of the battery, through R₁ ,
then through R₂ , then through R₃ .  It piles up on the right-hand side of
the capacitor (C).  It repels the ' + ' charges on the left side of 'C', and
those flow into the ' - ' side of the battery.  So the flow of current through
this series circuit is completely clockwise, around toward the right. 

That's the way the first experimenters pictured it, that's the way we still
handle it on paper, and that's the way our ammeters display it.

BUT . . .

About 100 years after we thought that we completely understand electricity,
we discovered that the little tiny things that really move through a wire, and
really carry the electric charge, are the electrons, and they carry NEGATIVE
charge.  This turned our whole picture upside down.

But we never changed the picture !  We still do all of our work in terms of
'conventional current'.  But the PHYSICAL current ... the actual motion of
charge in the wire ... is all exactly the other way around.

In your drawing ... When the switch is closed, electrons flow out of the 
' - ' terminal on the bottom of the battery, and pile up on the left plate of
the 'C'.  They repel electrons off of the right-side of 'C', and those then
flow through R₃ , then through R₂ , then through R₁ , and finally into the
' + ' terminal on top of the battery.

Those are the directions of 'conventional' current and 'physical' current
in all circuits.

In the circuit of YOUR picture that you attached, there's more to the story:

Battery current can't flow through a capacitor.  Current flows only until
charges are piled up on the two sides of 'C' facing each other, and then
it stops.

Wait a few seconds after you close the switch in the picture, and there is
no longer any current in the loop.

To be very specific and technical about it . . .

-- The instant you close the switch, the current is

       (battery voltage) / (R₁ + R₂ + R₃)        amperes

but it immediately starts to decrease.

--  Every  (C)/((R₁ + R₂ + R₃)  seconds after that, the current is

                  e⁻¹  =  about  36.8 %

less than it was that same amount of time ago.

Now, are you glad you asked ?
4 0
3 years ago
What are wind names according to direction
Vsevolod [243]

North, East, South, West (in order)

8 0
3 years ago
Show that liquid pressure is directly<br>proportional to height of liquid in a vessel.​
Norma-Jean [14]

Answer:

P=F/A where F is the weight of the water and A is the area on which it is resting. The weight of the water is mg. The mass of the water is dv where d is the density and v is the volume. Finally, the volume of the water in a vessel is equal to the area of the base of the vessel times the height of the vessel. (v=Ah)

Plugging everything in we get:

P = dAhg/A

So

P=dhg

So we have shown that liquid pressure is directly  proportional to height of liquid in a vessel.​

7 0
3 years ago
A disc on a frictionless axle, starting from rest (0 rpm) can spin up to a rotation rate of 3820 rpm in a period of 2 seconds. (
Eddi Din [679]

Answer:

1000 Nm

2000 Nm

1.00007 seconds

Explanation:

I = Moment of inertia = 5 kgm²

\alpha = Angular acceleration

\omega_f = Final angular velocity

\omega_i = Initial angular velocity

t = Time taken

Torque is given by

\tau=I\alpha\\\Rightarrow \tau=5\times 200\\\Rightarrow \tau=1000\ Nm

The torque of the disc would be 1000 Nm

If \alpha=400\ rad/s^2

\tau=I\alpha\\\Rightarrow \tau=5\times 400\\\Rightarrow \tau=2000\ Nm

The torque of the disc would be 2000 Nm

From equation of rotational motion

\omega_f=\omega_i+\alpha t\\\Rightarrow t=\frac{\omega_f-\omega_i}{\alpha}\\\Rightarrow t=\frac{3820\times \frac{2\pi}{60}-0}{400}\\\Rightarrow t=1.00007\ s

It would take 1.00007 seconds to reach 3820 rpm

6 0
4 years ago
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