Electric charges and fields

What is a charge?

It is the property of a substance that allows it to feel electric and magnetic fields

What is its SI and CGS unit?

SI → Coloumb
CGS → esu (electro static unit) = Franklin where 1 esu = 1 franklin

emu → 1 coulumb = 1/10 emu

What is the smallest unit of charge?

Frankline

What is the largest unit of charge?

Faraday

How much is 1 coulomb equal to in

1. Frankline

2. esu

3. Stat coloumb

4. emu

5. faraday

1. 3×10⁹

2. 3×10⁹

3. 3×10⁹

4. 10^-1

5. 965×10^-2

What is the numerical value for charge on an electron?

1.6×10^-19C

What is the mass of an electron?

9.1×10^-31 Kg

What is the formula for the charge that is being conducted on a sphere with radius R??

Q=4*π*ε_o​*R*V

Where:

• Q = charge

• R = radius of the sphere

• V = electric potential

• ε_o = permittivity of free space

What is the relation that you get between mass and speed from the theory of relativity?

Mass ∝ speed

What is the charge and mass of an alpha particle? WHat is it made up of?

mass = 4* mass of proton

charge = 2* charge of electron;

It is made up of 2 Protons and 2 Neutrons

What is the charge and mass of a proton?

• Charge = +1.602 × 10⁻¹⁹ C
  (That’s positive — same magnitude as electron, but opposite sign)

• Mass = 1.6726 × 10⁻²⁷ kg

What is the charge and mass of a deuteron? What is it made up of?

mass = 2*mass of proton

charge = same as electron;

It is made up of 1 proton and 1 neutron

What happens when a charge travels with constant velocity?

It becomes current and it has a magnetic and an electric field around it

What happens when a charge travels with acceleration?

It becomes current and it has magnetic, electric fields and emits electromagnetic (e.m.) waves around it

What is the value of ‘k’ in Coulomb’s law?

What is ε₀ called? What is its value??

Permittivity of free space; It is the property of the medium which would tell us the strength with which the medium would oppose the electrostatic force; 8.854×10⁻¹² C²/N

What change happens in the formula in Coulomb’s law to accommodate the change in one of its rules? What is that change?

The change that happened is:- Coulomb’s law is only applicable for vacuum/air, the change that happened is that it was now in a medium.

What is the formula for x in equilibrium in the repelling case?

x = d/(√n)+1

where,

x = Distance of the particle that is causing the system to attain equilibrium from the smaller charged particle

n = |q₂|/|q₁|

d → Distance of the particle from the larger charge

What is the formula for x in equilibrium in the attracting case?

x = d/(√n)-1

where,

x = Distance of the particle that is causing the system to attain equilibrium from the smaller charged particle

n = |q₂|/|q₁|

d → Distance of the particle from the larger charge

What is the formula for electric field strength/ electric field intensity

E = F/qo

Where,

E → Electric field strength / electric field intensity

F → Electrostatic force

qo → Charge that is present that has this electric field around it

What is the formula for finding out the angle of deviation?

What is the formula for finding out the electric field of a charge that is on the axis of a circle?

For a uniformly charged ring, what axial distance xxx from the centre gives the maximum electric field intensity?

Maximum value for x here is x = R/√2

What is the formula for finding out the net Electric field intensity due to a line charge??

We would need to first take out the components, which are given in the image

What is the formula for finding out the net Electric field intensity in an arc??

What is the formula for the elctric field due to a charged non-conducting sheet?

Where

σ → Surface charge density

What is the formula for finding out the electric field inside of a solid sphere

E = K*Q*r/R³

What is the electric field intensity on the surface or just outside the surface of the conductor?

It is always σ/ε₀

Where,

σ → Surface charge density

ε₀ → Efsar knot

What is the formula for electric dipole?

P = q*l
Where,
P → Electric dipole
q → Charge
l → length between the charge that is experiencing the dipole and one of the other charges

What is a positron?

It has the mass of an electron, the charge too, but has a +ve charge on it as compared to the electron’s -ve charge

What is the formula that we use when 2 charged objects of different radii share charge between themselves?

What is the charge on a up quark?

+2/3 electron

What is the charge on a down quark?

-1/3 electron

What is ionization energy?

It is the amount of energy required to break the valence electron in an insulator