1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
stellarik [79]
3 years ago
10

A tiny 0.0250 -microgram oil drop containing 15 excess electrons is suspended between to horizontally closely-spaced metal plate

s that carry equal but opposite charges on their facing surfaces. The plates are both circular with a radius of 6.50cm. (k = 1/4pi(epsilon)0 = 9.0 x 10^9 N x m^2/C^2, e = 1.6 x 10^-19 C)a) How much excess charge must be on each plate to hold the oil drop steady? (b) Which plate must be positive, the upper one or the lower one?
Physics
1 answer:
qaws [65]3 years ago
6 0

Answer:

(a) 12 × 10⁻³ C = 12 mC (b) The lower plate

Explanation:

Given

mass of oil drop, m = 0.025 μg =  0.025 × 10⁻⁶

radius of plates, r = 6.50 cm = 6.5 × 10⁻² m

k = 1/4πε₀ = 9.0 × 10⁹ Nm²/C²

electric charge, e= 1.6 × 10⁻¹⁹ C

charge on oil drop, q = 15e

charge on plates, Q = ?

First, we find the charge density of the plates, D = Q/A where Q = charge on plates and A = area of plates. Since the plates are circular, the area is given by A=πr² where r = radius of plates. D=Q/πr²

Also, the electric field, E between the plates is given by E = D/ε =Q/Aε = Q/ε₀πr².

The force on the oil drop due to the electric field between the plates is given by F = qE = qQ/ε₀πr².

Since the oil drop is suspended between the plates, it means that the electric force due to the field on the oil drop balances the weight of the oil drop. So, since weight of oil drop W = mg where g = 9.8 m/s². F =W (for oil drop suspension).

So, qQ/ε₀πr²=mg

So, Q=mgε₀πr²/q

From k = 1/4πε₀, ε₀=1/4πk

So, Q = mgπr²/4πkq = mgr²/4kq = (0.025 × 10⁻⁶ × 9.8 × (6.5 × 10⁻²)²)÷(4 × 9 × 10⁹ × 15 × 1.6 × 10⁻¹⁹)= 0.012 C = 12 mC

(b) The lower plate must be positive because, the direction of the electric field must be upwards, so as to balance out the weight of the oil drop so as to suspend it.

You might be interested in
A 20-cm-long spring is attached to a wall. When pulled horizontally with a force of 100 N, the spring stretches to a length of 2
Delvig [45]

Answer:

the length of stretched spring  in cm is 22

Explanation:

given information:

spring length, x1 = 20 cm = 0.2 m

force, F = 100 N

the length of spring streches, x2 = 22 cm = 0.22 m

According to Hooke's law

F = - kΔx

k = F/*=(x2-x1)

  = 100/(0.22 - 0.20)

  = 5000 N/m

if the spring is now suspended from a hook and a 10.2-kg block is attached to the bottom end

m = 10.2 kg

W = m g

    = 10.2 x 9.8

    = 99.96 N

F = - k Δx

Δx = F / k

     = 99.96 / 5000

     = 0.02

Δx = x2- x1

x2 = Δx + x1

    = 0.20 + 0.02

    = 0.22 m

     = 22 cm

7 0
3 years ago
The big bang theory has finally answered one of the biggest questions of science—the origin of the universe.
ss7ja [257]

Answer:

False

Explanation:

According to the big bang theory, matter was an infinitely small and very high density point which at one point exploded and expanded in all directions, creating what we know as our Universe, which also includes space and time . This happened about 13.8 billion years ago. Theoretical physicists have managed to reconstruct this chronology of events from 1/100 of a second after the Big Bang. After the explosion, while the Universe expanded, it cooled sufficiently and the first subatomic particles were formed: Electrons, Positrons, Mesons, Barions, Neutrinos, Photons among others. Today more than 90 particles are known. This theory solves many unknowns and is very well received by the scientific community, however there is still much to solve, for example, one of the great unsolved scientific problems in the expanding Universe model is whether the Universe is open or closed.

An attempt to solve this problem is to determine if the average density of matter in the Universe is greater than the critical value in Friedmann's model. The mass of a galaxy can be measured by observing the movement of its stars; multiplying the mass of each galaxy by the number of galaxies, it is seen that the density is only 5 to 10% of the critical value.

6 0
3 years ago
Which of the following is a false statement? Select one:
Art [367]

Answer:

The false statement is in option 'd': The center of mass of an object must lie within the object.

Explanation:

Center of mass is a theoretical point in a system of particles where the whole mass of the system is assumed to be concentrated.

Mathematically the position vector of center of mass is defined as

\overrightarrow{r}_{com}=\int \overrightarrow{r}_{i}dm

where,

\overrightarrow{r}_{i} is the position vector of the mass dm.

As we can see for homogenous symmetrical objects such as a sphere,cube,disc the center of mass is located at the centroid of the shapes itself but in many shapes it is located outside the body also.

Examples of shapes in which center of mass is located outside the body:

1) Horseshoe shaped body.

2) A thin ring.

In many cases we can make shapes of bodies whose center of mass lies outside the body.

6 0
3 years ago
EASY MATCHING PLEASE HELP!
kakasveta [241]
<h2><u>Answers:</u></h2><h2>1.) Right answer: polarization  </h2>

Alignment of light in only one vibrational orientation: polarization  

Normally, electromagnetic waves (light) are not polarized, so electromagnetic vibration occurs in all planes. But when we get these waves to vibrate in a single plane, we have polarized light.

This is possible because electromagnetic waves are transversal waves, this means the electric field oscillates in all normal directions to the direction of wave propagation.

In other words:

<em>Its oscillation occurs in the transversal direction to its propagation. </em>

So, when polarization occurs the electric field vibrates or oscillates in a given plane, called the <u>polarization plane</u>.

It should be noted that this phenomenon is only possible in transversal waves, in longitudinal waves, such as sound waves, polarization is not possible because its oscillation occurs in the same direction as its propagation.

<h2>2.) Right answer: concave  </h2>

Mirror that causes parallel incident rays of light to converge at the focus: concave  

A concave mirror, or convergent mirror, has a reflective surface that is curved inwards.

The concave mirrors reflect the light making it converge in a focal point therefore they are used to focus the light. This occurs because the light is reflected with different angles, since the normal to the surface varies from one point to another of the mirror.

<h2>3.) Right answer: photoelectric effect </h2>

phenomenon that can be explained only by a particle model for light: photoelectric effect  

Light can be considered as a wave or as particles (photons), in this context the photoelectric effect can only be explained based on the corpuscular model (particles) of light.

Then, the photoelectric effect consists of the emission of electrons (electric current) that occurs when light falls on a metal surface under certain conditions.

If the light is a stream of photons and each of them has energy, this energy is be able to pull an electron out of the crystalline lattice of the metal and communicate, in addition, a kinetic energy.

 

<h2>4.) Right answer: Taylor's experiment   </h2>

experiment that showed that diffraction effects could be attributed to light particles: Taylor's experiment  

This experiment was carried out by Geoffrey Taylor in 1909 with a flame as a light source, a diffraction grating and a photographic plate.

All this to test the diffraction of light.


<h2> 5.) Right answer: reflection  </h2>

principal use of mirrors: reflection

Mirrors fulfill the principle of reflection, which occurs when the light rays fall on a very flat reflecting surface are reflected so that the incident angle is equal to the reflected angle

<h2>6.) Right answer: mirage  </h2>

image of the sky seen on a hot road: mirage

A mirage is the product of an optical illusion due to the total reflection of the light when crossing layers of hot air of different density; this causes the perception of the inverted image of distant objects, as if they were reflected in the water.

<h2>7.) Right answer: virtual  </h2>

type of images always produced by convex  mirrors: virtual

In the convex mirrors the focus is virtual and the focal distance is negative. This is how the reflected rays diverge and only their extensions are cut at a point on the main axis, resulting in a virtual image of the real object.

<h2>8.) Right answer: diffraction  </h2>

pattern produced by light through a narrow slit: diffraction

Diffraction is a phenomenon that is based on the deviation of the waves (light waves in this case) when encountering an obstacle or going through a slit

<h2>9.) Right answer: convex  </h2>

shape of a converging lens: convex  

A convex lens is thicker in the center than at its edges and concentrates (converges) at a point the rays of light that pass through it.

<h2>10.) Right answer: dispersion  </h2>

separating light into component colors: dispersion  

The dispersion of light occurs when a beam of composite light is refracted (the different rays of light are diverted depending on their frequencies) in some medium, leaving their constituent colors separated.

The best known case is when a beam of white light from the sun passes through a prism, thus obtaining rays of different colors like those of the rainbow.


8 0
3 years ago
Read 2 more answers
Which of the following statements describes an interaction between the geosphere and atmosphere?
german
B is the answer, I’m really good at this subject
8 0
3 years ago
Read 2 more answers
Other questions:
  • What happens to the dependent variable in a controlled experiment?
    8·2 answers
  • GUESS WHAT? I'LL MAKE YOU BRAINLIEST!!! PLEASE ANSWER THING QUICKLY!
    7·1 answer
  • Demagnetize
    11·1 answer
  • Describe what is happening at the cascade range?
    6·1 answer
  • A projectile is launched at some angle to the horizontal with some initial speed vi, and air resistance is negligible.(a) Is the
    9·1 answer
  • What is the motion of the negative electrons and positive atomic nuclei caused by the external field?
    8·1 answer
  • Kiko writes a roport to compare and contrast the code of plants and animals. Which of the following statements is accurato arvd
    7·1 answer
  • The coefficent of static friction between the floor of a truck and a box resting on it is 0.28. The truck is traveling at 72.4 k
    15·1 answer
  • What is the anode in an alkaline battery?
    5·2 answers
  • Emma a total of 25 seconds to crawl 4 feet south and then 6 feet east.
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!