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Vinil7 [7]
4 years ago
14

Describe at least two changes that occurred to the atomic model over time, along with the experimental evidence that made these

changes necessary.
Help pleasee
Physics
2 answers:
e-lub [12.9K]4 years ago
6 0
I think you could use Bohr model and the Plum Pudding Model

Bohr Model : the one that states atoms consist of positively charged nucleus  and orbited by negatively charged electrons

Plum Pudding model : Atom consist of objects made to pieces with positive and negative charges

hope this helps
marta [7]4 years ago
5 0

Answer

There is a long story of atom. Many scientist gave different theories related to atom. Some of famous atomic modal are as follows

Thomson Atomic Modal

in 1904 J. J. Thomson proposed an atomic modal which is known as plum pudding modal. According to Thomson The shape of  an atom is spherical in which positively charged matter is filled and electrons are randomly scattered in that positively charged matter.

Experimental evidence

J.J. Thomson's experiments with cathode ray tubes showed that each atom has negatively charged particles which is known as electrons.

Rutherford atomic modal

in 1911, Rutherford gave  new atomic modal. He proposed the concept of nucleus. According to Rutherford atomic modal at the center of atoms all positively charged  particles are present and this center is known as nucleus. He said that negatively charge electrons revolves around the nucleus in particular orbit.

Experimental evidence:

In rutheford modal, Rutherford shooted alpha particles on very thin gold foil. He observed that some of the alpha particles get deflected by gold foil. which proved  proved that an atom has a  nucleus which is surrounded by  electrons.

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A pendulum is observed to complete 23 full cycles in 58 seconds. Use the definition of frequency to find the frequency.
Alex17521 [72]

Answer: f = 0.397 Hz

Explanation:

f = cycles per second

f = 23 / 58 = 0.39655...

4 0
3 years ago
Find the resistance at 50°c of copper wire 2mm in diameter and 3m long
mr Goodwill [35]
0.0179 ohms for copper.

0.0184 ohms for annealed copper



Ď = R (A/l) where

Ď = electrical resistivity

R = electrical resistance of a uniform specimen

A = cross sectional area

l = length



Solve for R by multiplying both sides by l/A

R = Ď(l/A)



The cross section of the wire is pi * 1^2 mm = 3.14159 square mm = 3.14159e-6 square meters.

The length is 3 meters. So l/A = 3/3.14159e-6 = 9.5493e5



Ď for copper is 1.68e-8 so 1.68e-8 * 9.5493e5 = 1.60e-2 ohms at 20 C

But copper has a temperature coefficient (α) of 0.00386 per degree C.

So the resistance value needs to be adjusted based upon how far from 20 C the temperature is.

50 - 20 = 30 C

So 0.00386 * 30 = 0.1158 meaning that the actual resistance at 50 C will be 11.58% higher.

So 1.1158 * 0.016 = 0.0179 ohms.



If you're using annealed copper, the values for Ď and the temperature coefficient change.

Ď = 1.72e-8

α = 0.00393



Doing the math, you get

1.72e-8 * 9.5493e5 * (1 + 30 * 0.00393) = 0.0184 ohms
8 0
3 years ago
What is the formula for speed or velocity?
alina1380 [7]

Answer:

c

Explanation:

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3 years ago
Un caballo parte del reposo y alcanza una velocidad de 15m/s en un tiempo de 8s. ¿ Cuál fue su aceleración y que distancia recor
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When a battery, a resistor, a switch, and an inductor form a circuit and the switch is closed, the inductor acts to oppose the c
vladimir1956 [14]

Answer:Time constant gets doubled

Explanation:

Given

L-R circuit is given and suppose R and L is the resistance and inductance of the circuit then current is given by

i=i_0\left [ 1-e^{-\frac{t}{\tau }}\right ]

where i_0 is maximum current

i=current at any time

\tau =\frac{L}{R}=time\ constant

\tau '=\frac{2L}{R}=2\tau

thus if inductance is doubled then time constant also gets doubled or twice to its original value.                                      

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4 years ago
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