Physics, 27.09.2019 04:30 LadyHolmes67

Alpha particles which have a charge +2e and mass 6.64 ✕ 10−27 kg are initially at rest and are fired directly at a stationary lead nucleus (charge +82e) at a speed of 1.95 ✕ 107 m/s. determine the distance of closest approach (in fm) before the alpha particle reverses direction. assume the lead nucleus remains stationary. assume the alpha particles are initially very far from a stationary lead nucleus.

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Answer from: colebuug9

The closest approach distance is 29.9 fm

Solution:

As per the question:

Charge on alpha-particle, q = +2e C

Charge on Lead nucleus, q' = +82e C

Speed of the $\alpha-particle$ , $v_{\alpha} = 1.95\times 10^{7} m/s$

Mass of $\alpha-particle$ , M = $6.64\times 10^{- 27} kg$

Now,

The kinetic energy of the $\alpha-particle$ :

$KE = \frac{1}{2}mv_{\alpha^{2}}$

Also the electro-static potential energy of the $\alpha-particle$ is given by:

$U_{E} = \frac{1}{4\piepsilon_{o}}\frac{qq'}{D}$

where

D = distance between the nucleus of $\alpha-particle$ and lead.

Since, the kinetic energy of the $\alpha-particle$ get tranformed into electro-static potential energy, thus equating the two:

$\frac{1}{2}mv_{\alpha^{2}} = \frac{1}{4\piepsilon_{o}}\frac{qq'}{D}$

$\frac{1}{2}\times 6.64\times 10^{- 27}\times (1.95\times 10^{7})^{2} = (9\times 10^(9))\frac{2e.82e}{D}$

$D = (9\times 10^(9))\frac{164\times (1.6\times 10^{- 19})^{2}}{1.26\times 10^{- 12}} = 2.99\times 10^{- 14} m = 2.99\times 10^{- 14} m = 29.9 fm$

Answer from: Quest

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia

Answer from: Quest

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me