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What Does Q Mean In Physics

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What Is Electric Charge

What do you mean by Q value of a nuclear reaction? | 12 | ATOMS AND NUCLEI | PHYSICS | PRADEEP |…

In physics, charge, also known as electric charge, electrical charge, or electrostatic charge and symbolized q, is a characteristic of a unit of matter that expresses the extent to which it has more or fewer electrons than protons. In atoms, the electron carries a negative elementary or unit charge the proton carries a positive charge. The two types of charge are equal and opposite.

In an atom of matter, an electrical charge occurs whenever the number of protons in the nucleus differs from the number of electrons surrounding that nucleus. If there are more electrons than protons, the atom has a negative charge. If there are fewer electrons than protons, the atom has a positive charge. The amount of charge carried by an atom is always a multiple of the elementary charge, that is, the charge carried by a single electron or a single proton. A particle, atom, or object with negative charge is said to have negative electric polarity a particle, atom, or object with positive charge is said to have positive electric polarity.

An electric field, also called an electrical field or an electrostatic field, surrounds any object that has charge. The electric field strength at any given distance from an object is directly proportional to the amount of charge on the object. Near any object having a fixed electric charge, the electric field strength diminishes in proportion to the square of the distance from the object .

F = / (4

Example 2 Calculating The Force Exerted On A Point Charge By An Electric Field

What force does the electric field found in the previous example exert on a point charge of 0.250 C?


Since we know the electric field strength and the charge in the field, the force on that charge can be calculated using the definition of electric field \mathbf=\frac}\\ rearranged to F = qE.


The magnitude of the force on a charge q = 0.250 C exerted by a field of strength E = 7.20 × 105 N/C is thus,

\beginF& =& -qE\\\text& =& \left\left\\\text& =& 0.180\text\end\\

Because q is negative, the force is directed opposite to the direction of the field.


The force is attractive, as expected for unlike charges. The charges in this example are typical of common static electricity, and the modest attractive force obtained is similar to forces experienced in static cling and similar situations.

Lack Of Fractional Charges

Paul Dirac argued in 1931 that if magnetic monopoles exist, then electric charge must be quantized however, it is unknown whether magnetic monopoles actually exist. It is currently unknown why isolatable particles are restricted to integer charges much of the string theory landscape appears to admit fractional charges.

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What Is The Meaning Of Magnitude In Physics


Any quantitys magnitude is a number that indicates how large or small a measurement of a physical quantity is in comparison to a given reference value .

  • In physics, magnitude is described in simple words as distance or quantity.
  • It shows the direction or size that is absolute or relative in which an object moves in the sense of motion.
  • It is used to describe the size or extent of something.
  • Generally, in physics, magnitude relates to distance or quantity. Magnitude defines the size of an entity, or its speed when moving, in comparison to motion.

For example:

The vector quantities are also related to their direction and magnitude. Displacement, velocity, acceleration, force, and other vector quantities are examples. The absolute value of a vector is referred to as its magnitude.

We can determine that two vectors are equal only if their magnitude and direction are the same. The magnitude of a vector changes when it is multiplied by a positive number, but the direction remains the same. A vectors magnitude and direction will both change if it is multiplied by a negative value.


Therefore, in physics, the magnitude of any quantity tells us how big a physical quantity or measurement is in comparison to some other quantitys reference value. A physical quantity is represented mathematically as a combination of a numerical value and a unit. The magnitude of a physical quantity is the numerical value associated with a measurement of that quantity.

Is Electric Charge A Vector Quantity

particle physics

Electric charge is a scalar quantity. Apart from having a magnitude and direction, a quantity to be termed a vector should also obey the laws of vector addition, such as triangle law of vector addition and parallelogram law of vector addition only then the quantity is said to be a vector quantity. When two currents meet at a junction in the case of an electric current, the resultant current of these will be an algebraic sum and not the vector sum. Therefore, an electric current is a scalar quantity, although it possesses magnitude and direction.

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What Are The 26 Science Terms

Possible answers include: A astronomy, B biology, C chemistry, D diffusion, E experiment, F fossil, G geology, H heat, I interference, J jet stream, K kinetic, L latitude, M motion, N neutron, O oxygen, P physics, Q quasar, R respiration, S solar system, T thermometer, U

Electric Charge And Coulomb’s Law


  • there are two kinds of charge, positive and negative
  • like charges repel, unlike charges attract
  • positive charge comes from having more protons than electrons negative charge comes from having more electrons than protons
  • charge is quantized, meaning that charge comes in integer multiples of the elementary charge e
  • charge is conserved

Probably everyone is familiar with the first three concepts, but what does it mean for charge to be quantized? Charge comes in multiples of an indivisible unit of charge, represented by the letter e. In other words, charge comes in multiples of the charge on the electron or the proton. These things have the same size charge, but the sign is different. A proton has a charge of +e, while an electron has a charge of -e.

Electrons and protons are not the only things that carry charge. Other particles also carry charge in multiples of the electronic charge. Those are not going to be discussed, for the most part, in this course, however.

Putting “charge is quantized” in terms of an equation, we say:

q = n e

q is the symbol used to represent charge, while n is a positive or negative integer, and e is the electronic charge, 1.60 x 10-19 Coulombs.

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Example 1 Calculating The Electric Field Of A Point Charge

Calculate the strength and direction of the electric field E due to a point charge of 2.00 nC at a distance of 5.00 mm from the charge.


We can find the electric field created by a point charge by using the equation E=\frac\\.


Here Q = 2.00 × 109 C and r = 5.00 × 103 m. Entering those values into the above equation gives

\beginE& =& k\frac\\\text& =& \left\times\frac\text\right)}\text\right)^2}\\\text& =& 7.19\times10^5\text\end\\


This electric field strength is the same at any point 5.00 mm away from the charge Q that creates the field. It is positive, meaning that it has a direction pointing away from the charge Q.

What Does A Gradient Mean In Physics

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I’m a physics high school student and have learned about the term ‘gradient’ regarding a few situations, such as pressure gradients and temperature gradients.

But what does this really mean? What is the physics meaning of gradient? I know that the pressure gradient is $\frac$ and the temperature gradient is $\frac$. If we take the $dx$, for instance, as an extremely small number, then the gradient approaches towards a very large value. What does this imply? Please explain in simple language!

  • 2$\begingroup$Do not forget that P is a function of x, so if P is continuous, then if dx is small then dP is small too, the ratio is independent of the value of dx if dx is small$\endgroup$ user126422Feb 24 ’17 at 3:46
  • 1Feb 24 ’17 at 6:07
  • 1$\begingroup$Please use mathjax to format mathematical expressions. To learn more about mathjax, please read MathJax basic tutorial and quick reference.$\endgroup$ YashasFeb 24 ’17 at 6:23
  • $\begingroup$Appreciate the edits Yashas 🙂 I made a lazy choice not to, and that is on me.$\endgroup$

I struggled with the concept myself even in later calculus … which is a real problem when a meteorology major!

But one day it just dawned on me that it’s as simple as it sounds. It’s the rate of difference.

Gradient refers to how steep a line is, which is basically the slope.$\frac$ and $\frac$ are basically the derivative of a function, i.e its slope.

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Why Is Static Electricity More Apparent In Winter

You notice static electricity much more in winter than in summer because the air is much drier in winter than summer. Dry air is a relatively good electrical insulator, so if something is charged the charge tends to stay. In more humid conditions, such as you find on a typical summer day, water molecules, which are polarized, can quickly remove charge from a charged object.

What Is The Difference Between Electricity And Magnetism

Electricity can be present in a static charge, while magnetisms presence is only felt when there are moving charges as a result of electricity. In simple words, electricity can exist without magnetism, but magnetism cannot exist without electricity. What are the types of electricity? What are the sources of electricity?

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What Does The 3 Dot Triangle Tattoo Mean

When the three dots tattoo is arranged in a triangular shape, it is commonly associated with prison life and criminality. The triangular three dots tattoo generally stands for the concept of mi vida loca, Spanish for my crazy life and is typically associated with the gang community and lengthy prison sentences.

From The Josephson And Von Klitzing Constants

Definitions,scientific reasons and mcqs of physics (motion)

Another accurate method for measuring the elementary charge is by inferring it from measurements of two effects in quantum mechanics: The Josephson effect, voltage oscillations that arise in certain superconducting structures and the quantum Hall effect, a quantum effect of electrons at low temperatures, strong magnetic fields, and confinement into two dimensions. The Josephson constant is


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What Does The Triangle Delta Mean In Physics

What does the triangle delta mean in physics? In general physics, delta-v is a change in velocity. The Greek uppercase letter is the standard mathematical symbol to represent change in some quantity. Depending on the situation, delta-v can be either a spatial vector or scalar .

What does the triangle delta mean? In trigonometry, lower-case delta represents the area of a triangle. B. Uppercase delta at oftentimes means change or the change in maths.

What does the symbol mean? A change in value. Often shown using the delta symbol: Example: x means the change in the value of x When we do simple counting the increment is 1, like this: 1,2,3,4,

What do the symbols and indicate? +: A symbol which indicates that an atom or region with a deficiency of electron density, often because of resonance delocalization, electronegativity differences, or inductive effects.

What Is The Difference Between Q And Q

4.1/5q and QQq

Also to know is, what is the difference between Q and Q in electricity?

Big Q represents the source charge which creates the electric field. Little q represents the test charge which is used to measure the strength of the electric field at a given location surrounding the source charge.

Also, why is charge denoted by Q? This predominance or deficiency of electrons, the principle we know as “charge,” was also called the quantity of electricity.” “E” referred to electrons, so “Q,” after the first word of that phrase, came to represent charge. Wikipedia notes that the term ‘quantity of electricity’ was once common in scientific

Beside this, what is the Q in Coulomb’s law?

Charge comes in multiples of an indivisible unit of charge, represented by the letter e. q is the symbol used to represent charge, while n is a positive or negative integer, and e is the electronic charge, 1.60 x 10-19Coulombs.

What is the constant q in physics?

1.602176634×1019 C. The elementary charge, usually denoted by e or sometimes qe, is the electric charge carried by a single proton or, equivalently, the magnitude of the negative electric charge carried by a single electron, which has charge 1 e . This elementary charge is a fundamental physical constant.

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In Terms Of The Avogadro Constant And Faraday Constant

If the Avogadro constantNA and the Faraday constantF are independently known, the value of the elementary charge can be deduced using the formula

e . }}}.}

” rel=”nofollow”> mole of electrons, divided by the number of electrons in a mole, equals the charge of a single electron.)

This method is not how the most accurate values are measured today. Nevertheless, it is a legitimate and still quite accurate method, and experimental methodologies are described below.

The value of the Avogadro constant NA was first approximated by Johann Josef Loschmidt who, in 1865, estimated the average diameter of the molecules in air by a method that is equivalent to calculating the number of particles in a given volume of gas. Today the value of NA can be measured at very high accuracy by taking an extremely pure crystal , measuring how far apart the atoms are spaced using X-ray diffraction or another method, and accurately measuring the density of the crystal. From this information, one can deduce the mass of a single atom and since the molar mass is known, the number of atoms in a mole can be calculated: NA = M/m.

The limit to the precision of the method is the measurement of F: the best experimental value has a relative uncertainty of 1.6 ppm, about thirty times higher than other modern methods of measuring or calculating the elementary charge.

What Does The Negative Sign Mean In The General Formula For The Work Done In Moving A Charge From One Point To Another In Any Electric Field A Only Negative Charges Are Being Considered To Be Moved In The Given Electric Field B The Charge Being Moved Always Loses Its Energy To The Surroundings C The Work Done In Moving The Charge Is Against The Electric Field D The Movement Of The Charges Are Always Oriented Such That It Moves To The Left Or Downwards

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What does the negative sign mean in the general formula for the work done in moving a charge from one point to another in any electric field?

a.) Only negative charges are being considered to be moved in the given electric field.

b.) The charge being moved always loses its energy to the surroundings.

c.) The work done in moving the charge is against the electric field.

d.) The movement of the charges are always oriented such that it moves to the left or downwards.

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Distinguishing Temperature Heat And Internal Energy

Using the kinetic theory, a clear distinction between these three properties can be made.

  • Temperature is related to the kinetic energies of the molecules of a material. It is the average kinetic energy of individual molecules.
  • Internal energy refers to the total energy of all the molecules within the object. It is an extensive property, therefore when two equal-mass hot ingots of steel may have the same temperature, but two of them have twice as much internal energy as one does.
  • Finally, heat is the amount of energy flowing from one body to another spontaneously due to their temperature difference.

It must be added, when a temperature difference does exist heat flows spontaneously from the warmer system to the colder system. Thus, if a 5 kg cube of steel at 100°C is placed in contact with a 500 kg cube of steel at 20°C, heat flows from the cube at 300°C to the cube at 20°C even though the internal energy of the 20°C cube is much greater because there is so much more of it.

A particularly important concept is thermodynamic equilibrium. In general, when two objects are brought into thermal contact, heat will flow between them until they come into equilibrium with each other.

Internal energymicroscopic scaleUU

U = Upot + Ukin

The microscopic potential energy, Upot, involves the chemical bonds between the atoms that make up the molecules, binding forces in the nucleus and also the physical force fields within the system .

What Is The Quantum Of Charge

All known elementary particles, including quarks, have charges that are integer multiples of 1/3 e. Therefore, one can say that the “quantum of charge” is 1/3 e. In this case, one says that the “elementary charge” is three times as large as the “quantum of charge”.

On the other hand, all isolatable particles have charges that are integer multiples of e. Therefore, one can say that the “quantum of charge” is e, with the proviso that quarks are not to be included. In this case, “elementary charge” would be synonymous with the “quantum of charge”.

In fact, both terminologies are used. For this reason, phrases like “the quantum of charge” or “the indivisible unit of charge” can be ambiguous unless further specification is given. On the other hand, the term “elementary charge” is unambiguous: it refers to a quantity of charge equal to that of a proton.

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