The spontaneous emission rate for the 21-cm hyperfine line in hydrogen can be determined by considering the magnetic dipole transition. Due to the mass difference between the electron (me) and proton (mp), the proton contribution is negligible. Therefore, we focus on the electron's magnetic moment (πe = -e/me se) and the singlet-triplet configurations.
The transition rate (a) can be expressed as:
a = w30 e²/3πε₀hc⁵m²e |〈1|se|0〉|²
To find |〈1|se|0〉|², we need to choose a triplet state (e.g., |1〉) and use the relevant formulas from Equations 4.175 and 4.176.
After calculating |〈1|se|0〉|², plug in the actual numbers for the fundamental constants (e, ε₀, h, c, and me). Then, compute the transition rate (a) and the lifetime of the triplet state.
Based on the given answer, the lifetime of the triplet state is approximately 1.1 × 10⁷ years.
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Can anyone help in physics plz
Answer:
The answer is B. 8000.
Explanation:
She gained 10,000J , but when she reached the bottom she was at 2,000J. All you need to do is 10,000-2,000 and you get 8,000. So the answer is 8,000J.
What was an ill effect of the industrial revolution?
A)air pollution
B)crowded and unhealthy conduction in cities
C)child labor
D)all of the above
Answer:
answer is option (c) child labour
Difference between crest and trough
Answer:
The highest surface part of a wave is called the crest, and the lowest part is the trough. The vertical distance between the crest and the trough is the wave height. The horizontal distance between two adjacent crests or troughs is known as the wavelength.
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An object has a kinetic energy of 25 J and a mass of 34 kg, how fast is the object moving?
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the value of acceleration due to gravity (g) will be maximum at:
a) 1/2 of the radius of earth
b) 1/4 of the radius of earth
c) 1/8 of the radius of earth
Answer:
1/4
Explanation:
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What is the major source of energy on Earth? Group of answer choices a.photosynthesis b.fossil fuels c.EM waves from the sun d.
plants that are used for food.
Answer:
Em waves from the sun d
Explanation:
Answer:
The answer is photosynthesis
Explanation:
Write a 5-8 sentence summary on Earthquakes.
Answer:
An earthquake is a sudden shaking movement of the surface of the earth. It is known as a quake, tremblor or tremor. Earthquakes can range in size from those that are so weak that they cannot be felt to those violent enough to toss people around and destroy whole cities. ... An earthquake is measured on Richter's scale.
PLEASE MARK ME BRAINLIEST, PLEASEHow many kgs are in 1000N?
Answer:
this much I think 101.9716212978
Answer:
approximately 102kg
Explanation:
1 kg on the surface of the Earth weighs 9.80665 N
1000 N = 1000/9.80665 kg = 102 kg
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Analyzing Ideas A friend claims to have built a
motor by attaching a shaft to the core of a galva-
nometer and removing the spring. Can this motor
rotate through a full rotation? Explain your answer.
Answer:
Yes, the magnet force will cause the motor rotate through a full rotation. So the friend who claims to have built a motor by attaching a shaft to the core of a galvanometer and removing the spring is correct.
An 80 kg skier stands at the top of a 40-meter slope. She then skis down the slope. What is her approximate speed at the bottom of the slope if friction is negligible and her kinetic energy is 31360 J?
Thank you for that information. If we know her mass and kinetic energy, then we don't need any of that other business about the height of the slope, her skiing ability, the friction of the snow, what she uses to wax her skis, the color of her parka, or what she had for lunch at the chalet. The mass and kinetic energy are enough to answer the question.
Kinetic Energy = (1/2) · (mass) · (speed)²
31,360 J = (1/2) · (80 kg) · (speed)²
speed² = (31,360 J) / (40 kg)
speed² = 784 m²/s²
speed = 28 m/s
in which of the following is the molecules of water moving fatest A. stream. B. ice. C. ice water mixture. d. water.
Answer:
steam
Explanation:
particles move faster in a gas than in a liquid or solid
What will happen in the next moment for the girl on the swing?
1.Fill in wether quantities will increase, decrease, or stay the same.
2. Support your answer in the table below
Answer:
Increase, same, same
Explanation:
A dog runs down his driveway with an initial speed of 5.0 m/s for 8 seconds then uniformly increases his speed to 10 m/s in 5 seconds, how long is the driveway? SHOW WORK
Answer:
to find the displacement, or delta x (change in position) on a velocity graph, you can find the area under the line on the graph: between 1 and 8 seconds, the dog was going at 5m/s, so 5m/s x 8s=40m, for the second part, you have to find the area of both a triangle and a rectangle, so the rectangle would be 5m/s x 5s=25m and the area under the triangle would be (5m/s x 5s)/2=25m/2=12.5m -you divide by 2 because it's a triangle
-afterwards, you would add the area of the 2 sections together, so 40m+25m+12.5m=77.5m
Explanation:
True or false: Everything in the universe works with harmony because of balanced energy
Answer:
Explanation:
True
Answer:
True..................
A ball dropped and accelerates downwards at a rate of 10m/s^2 for 15 seconds how much will the balls velocity increase
Answer:
v = 150 m/s
Explanation:
Given that,
The acceleration of the ball, a = 10 m/s²
Time, t = 15 s
We need to find the increase in ball's velocity. When it is dropped its initial velocity is equal to 0. Let v be the velocity,
v = u+at
v = 0 +10(15)
v = 150 m/s
So, the ball's final velocity is 150 m/s.
If there is zero total force acting on the refrigerator, the refrigerator would
A) slow down
B) speed up
C) remains the same speed
D) slow down, change direction and then speed up going the other way
E) remains at the same speed, but changes direction
Answer:
c
Explanation:
this is because newton's first law of motion states that every object will continue in its state of rest or uniform motion in a straight line unless a resultant force acts on it
so if the resultant force on the refrigerator is 0N, but it was initially moving, it will continue in its motion in a straight line.
it will not change direction since it will continue in its uniform motion.
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lab number 14: sudden stops hurt newtons first law
Answer:
you want to know newtons first law here.
Explanation:
An object that is at rest stays at rest or stays in motion.
Match each word to it's correct meaning.
1. conduction
A.resistance to motion between two objects in contact
2. convection
B.something that will flow
3. fluid
C.measure of how much heat energy a substance has
4. friction
D.transmission of heat by the transferring of energy from one particle to another
5. temperature
E.transfer of heat by the motion of the particles of a gas or fluid
PLS PLS PLS NEED HELP ONLY HAVE A LITTLE BIT TILL I HAVE TO SHOW ME PARENTS ME GRADES AND I CANT HAVE ANYTHING OVERDUE
Answer:
you know the answer i answered it before on a question 0-0
Explanation:
SI UNIT OF GRAVITY is the
Answer:
G
Explanation:
A force of 100 N will exert the greatest pressure on an area of
Answer:
It will apply the greatest pressure of an area of 1.
Explanation:
To find pressure use the formula P = F/A
P = 100/1
P = 100
Answer:
10 N / cm^2
Explanation:
The Formiula is P = F / A
P = presure
F = Force in Newtons
A = area.
The answer is the smaller the area the larger the pressure.
The smallest area you have given us is 10 cm^2
The Pressure = 100N / 10 cm^2
Pressure = 10 N/cm^2
Note: the units are not exactly standard units, but I've given the answer the way the question offers the units.
2. True or False: Molecules always vibrate at the same speed??
Answer:
False
Explanation:
There are 3 states of matter, and all states have molecules. These molecules vibrate in different speeds, depending on the mass, weight, and stae off matter of the object.
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Answer: the last one
Explanation:
Answer:
C
Explanation:
a effort of 100n can raise a load of 2000n in a hydraulic press. calculate the cross-sectional area of a small piston in it. The cross-sectional area of a large piston is 4m^s
Answer:
[tex]A_{1}[/tex] = 0.2 [tex]m^{2}[/tex]
Explanation:
The pressure on the pistons is given as;
Pressure = [tex]\frac{Force}{Area}[/tex]
So that,
Pressure on the small piston = [tex]\frac{F_{1} }{A_{1} }[/tex] and Pressure on the large piston = [tex]\frac{F_{2} }{A_{2} }[/tex]
Thus,
[tex]\frac{F_{1} }{A_{1} }[/tex] = [tex]\frac{F_{2} }{A_{2} }[/tex]
Given that: [tex]F_{1}[/tex] = 100 N, [tex]F_{2}[/tex] = 2000 N, [tex]A_{2}[/tex] = 4 [tex]m^{2}[/tex].
[tex]\frac{100}{A_{1} }[/tex] = [tex]\frac{2000}{4}[/tex]
[tex]A_{1}[/tex] = [tex]\frac{100*4}{2000}[/tex]
= [tex]\frac{400}{2000}[/tex]
= 0.2
[tex]A_{1}[/tex] = 0.2 [tex]m^{2}[/tex]
The area of the small piston is 0.2 [tex]m^{2}[/tex].
_____ is a area of darkness
Answer:
Shadow
Explanation:
Shadow is a area of darkness.
When sunlight falls on an object ot blocks the light from getting onto the surface . Hence, as light does not falls on that region it is dark. Hence, the shadow is the area of darkness.
Answer:
shadow is a area of darkness
what is the answer , please.
Answer:
39.2m/s
Explanation:
V = 0
V = u - gt
0 = u - 9.8×4
u = 39.2
what is biodiversity
Answer:
Biodiversity is the variety and variability of life on Earth. Biodiversity is typically a measure of variation at the genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near the equator, which is the result of the warm climate and high primary productivity.
Explanation:
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Can u please help mee?
1 Calculate the momentum in each of these cases.
a A car of mass 1000 kg traveling at 31.6 m/s
b A train with a mass of 120 000 kg and a velocity of 40 m/s (about 90 mph)
Answer:
a
Explanation:
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An atom of a certain element has 36 protons, 36 electrons, and a mass number of 84. At room temperature, this element is a very stable gas. How many neutrons are in this atom?
Answer:
12 neutrons
Explanation:
The number of protons also shows the atomic number. Therefore the element in question is Krypton (Kr), which also is a noble gas.
Neutrons = Mass number - protons - electrons
Here neutrons = 84 - 36 - 36 = 12
what is mass in physics
Answer:
Mass, in physics, quantitative measure of inertia, a fundamental property of all matter. It is, in effect, the resistance that a body of matter offers to a change in its speed or position upon the application of a force. The greater the mass of a body, the smaller the change produced by an applied force.
Explanation:
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Answer:
Mass, in physics, quantitative measure of inertia, a fundamental property of all matter. It is, in effect, the resistance that a body of matter offers to a change in its speed or position upon the application of a force. The greater the mass of a body, the smaller the change produced by an applied force.
Explanation:
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How electromagnet works in circuit breaker
Explanation:
A circuit breaker is an automatic switch that cut off current in a circuit when the current become too large. When the current in a circuit increases, the strength of the electromagnet will increase in accordance; this will pull the soft iron armature towards the electromagnet.