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4 years ago

Most radiation exposure comes from

2 answers:

5 0

Most radiation exposure comes from natural sources. These so-called "natural sources" include Radon, Internal, Terrestrial, and Cosmic. Among that, Radon proves to be the largest source of radiation. Radon is a naturally occurring radioactive gas that comes from the breakdown of uranium.

Yuliya22 [10]4 years ago

3 0

Answer:

d. natural source

Explanation:

When energy is emitteds by a source and travels through a medium until it's absorbed by matter, radiation is occuring. We are exposed to radiation everyday, some sources of radiation are natural and other come from man-made elements. We are commonly exposed to Background radiation, from Earth itself (some minerals) and very few man-made objects. From this type of radiation comes the one we are the most exposed to emitted by Radon and Thoron (radioactive gases which are created when other naturally occurring elements undergo radioactive decay). This gases represent 37% of all the radiation we are commonly exposed to.

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A certain metal with work function of Φ = 1.7 eV is illuminated in vacuum by 1.4 x 10-6 W of light with a wavelength of λ = 600

Makovka662 [10]

Answer:

1) n = 4.47*10^12 photons

2) K = 0.25 eV

Explanation:

This is a problem about the photoelectric effect.

1) In order to calculate the number of photons that impact the metal, you take into account the power of the light, which is given by:

$P=\frac{E}{t}=1.4*10^{-6}\frac{J}{s}$ (1)

Furthermore you calculate the energy of a photon with a wavelength of 600nm, by using the following formula:

$E_p=h\frac{c}{\lambda}$ (2)

c: speed of light = 3*10^8 m/s

h: Planck's constant = 6.626*10^-34 Js

λ: wavelength = 600*10^-9 m

You replace the values of the parameters in the equation (2):

$E_p=(6.626*10^{-34}Js)\frac{3*10^8m/s}{600*10^{-9}m}=3.131*10^{-19}J$

Next, you calculate the quotient between the power of the light (equation (1)) and the energy of the photon:

$n=\frac{P}{E_p}=\frac{1.4*10^{-6}J/s}{3.131*10^{-19}J}=4.47*10^{12}photons$

The number of photons is 4.47*10^12

2) The kinetic energy of the electrons emitted by the metal is given by the following formula:

$K=E_p-\Phi$ (3)

Ep: energy of the photons

Φ: work function of the metal = 1.7 eV

You first convert the energy of the photons to eV:

$E_p=3.131*10^{-19}J*\frac{6.242*10^{18}eV}{1J}=1.954eV$

You replace in the equation (3):

$K=1.95eV-1.7eV=0.25eV$

The kinetic energy of the electrons emitted by the metal is 0.25 eV

6 0

4 years ago

Lightning a. occurs when a positively charged cloud base induces a negative charge on the Earth's surface. b. travels most often

mart [117]

Answer:

c. may be accompanied by the sound of explosively expanding hot air, called thunder.

Explanation:

Lightning is a discharge which is due to the reaction between oppositely charged charges in the clouds, or between clouds base and the Earth surface.

The motion of the cloud causes charging of clouds by friction, thus the reaction between opposite charges (jumping of charges from one cloud to another) in the cloud can lead to lightning. Also, oftentimes the bottom of a cloud is negatively charged so that this is attracted to the positive charge on the earth surface. Thus leading to a discharge called lightning.

Thus in the given question, the appropriate option is C. This implies that, lightning may be accompanied by the sound of explosively expanding hot air, called thunder.

8 0

3 years ago

Two satellites are in circular orbits around a planet that has radius 9.00×106m. One satellite has mass 68.0 kg, orbital radius

34kurt

Answer: 6782 m/s

Explanation:

Given

Radius of the planet, r = 9*10^6 m

Mass of satellite 1, m1 = 68 kg

Radius of satellite 1, r1 = 6*10^7 m

Orbital speed of satellite 1, vs1 = 4800 m/s

Mass of satellite 2, m2 = 84 kg

Radius of satellite 2, r2 = 3*10^7 m

Orbital speed of satellite 2, vs2 = ?

We know that magnitude of gravitational force, F = (G.m.m•) / r²

Where,

m = mass of satellite

m• = mass of planet

r = radius of orbit

If we consider Newton's second law that states that, F = ma, thus

F(g) = ma(rad)

Where, a(rad) = v²/r

F(g) = mv²/r

Substituting in the initial equation

mv²/r = (G.m.m•) / r²

v² = (G.m•) / r

v = √[G.m•/r]

To find vs2, we first need to find mass of the planet, m• we know that G is a gravitational constant, so we plug in the values

vs1 = √[G.m•/r1]

4800 = √[(6.67*10^-11 * m•) / 6*10^7]

4800² = (6.67*10^-11 * m•) / 6*10^7

2.3*10^7 * 6*10^7 = 6.67*10^-11 * m•

1.38*10^15 = 6.67*10^-11 * m•

m• = 1.38*10^15 / 6.67*10^-11

m• =2.07*10^25 kg

Having found that, we use the value to find our vs2

vs2 = √[(G.m•) / r2]

vs2 = √[(6.67*10^-11 * 2.07*10^25) / 3*10^7]

vs2 = √(1.38*10^15 / 3*10^7)

vs2 = √4.6*10^7

vs2 = 6782.33 m/s

Therefore, the orbital speed of the second satellite is 6782 m/s

4 0

4 years ago

Read 2 more answers

Can anyone answer this fast pls

nekit [7.7K]

I believe the answer would be 4.5. because it wouldnt be c or d. and 2 seems too small.

3 0

3 years ago

Most irregular galaxies are thought to have formed _____

Musya8 [376]

Most irregular galaxies were have thought to have been formed from collisions from other galaxies <span />

6 0

4 years ago

Read 2 more answers