Flashcards in Electrostatics. Deck (33):

1

## What is charge q in terms of number of electrons e ?

### q=ne

2

## Coulumbs Law

###
F= k q1q2/ r^.

k=1/4πε₀

unit of k = N metre square per coulomb square

k= 9 x 10^9

ε₀= 8 x 10^-12

3

## Unit of k in electrostatics Coulomb's law

### N m^ c^-2

4

## Unit of ε₀ (permittivity of free space )

### C^/N m^-2

5

## Field strength due to a point charge

### E= k q/r^

6

## Direction of field strength due to positive and negative charge ?

### Due to positive charge field strength is away from the charge and due to negative charge field strength is towards the charge.

7

## Electric potential V due to point charge

### V= k q/r

8

## Electrostatic potential energy U of two point charges.

### U= k q1q2/r

9

## What is electrostatic potential energy in terms of charge and electrostatic potential ?

### U= qV

10

## Potential difference in an uniform electric field?

### In an indoors electric field , potential difference V= Ed

11

## Formula of electric dipole

### p=q(2a). Direction of p vector is from -q to +q

12

## Electric field strength E for a uniformly charged spherical shell

###
E(i)=0

E(s)=k q/R^= σ/ε₀

Eo= kq/r^

13

## Electric field strength e for a solid sphere of charge.

###
E(i)=Kqr/R³

E(s)=Kq/R^

Eo=Kq/r^

14

## Electric field strength E on the axis of a uniformly charged ring

###
E= Kqx÷(R²+x²)^3/2

At centre , x= 0 and hence E=0

15

## Electric field Strength E for a infinitely long line charge

### E= λ/2πε₀r

16

## Electric potential V for a uniformly charged spherical shell

###
V(i) = V(s) = Kq/R=σR/ε₀

Vo=Kq/r

17

## Electric Potential for a solid sphere of charge

###
V(i)= Kq÷R³(1.5 R² - 0.5 r²)

V(s)=Kq/R

Vo=Kq/r

18

## Electric potential on the axis of a uniformly charged ring

###
V=Kq÷√R²+x²

At centre ,

x=0

V= Kq/R

19

## Electric Potential V for an infinitely long line charge

### PD= λ÷2πε₀ ln (r₂/r₁)

20

## Torque due to an electric dipole when placed in an uniform electric field

### Torque = pE sin #

21

## Electric potential energy U due to an electric dipole when placed in a uniform electric field

### U=-PE= -pE cos#

22

## When an electric dipole is placed in an uniform electric field , what happens when #=0?

###
In #=0 , it's a stable equilibrium position.

In this position , F=0

Torque =0

U=-p.E= minimum

23

## When an electric dipole is placed in an uniform electric field , what happens when #=180?

### #=0 is unstable equilibrium position. In this F=0 and torque = 0 but U= +p.E= maximum.

24

## Electric flux on surface formula ?

### ∫∞=∫E . dS

25

## Mathematically , what is Gauss Law?

###
∫E . dS= q(in) / ε₀

or 'Electric Flux from a closed surface'= q(in) / ε₀

26

## Electric filed due to a plane sheet of charge

### E=σ/2 ε₀

27

## What is electric field on the surface of any charged conducting body ?

### E=σ/ε₀

28

## Electric filed of a conductor under electrostatic conditions?

###
E(i)= 0

E(s) = σ/ε₀

29

## What are the two properties of a conductor regarding electric field lines and electric potential.

###
1.On the surface of charged conductor electric lines are perpendicular to the surface

2. The potential of charged conductor through out its volume is same.

30

## Potential difference between two charged spherical shells

### V1-V2=q1÷4πε₀(1/r1-1/r2)

31

## What is charge per unit length λ?

###
It's charge distribution along a line.

dq = λ dx

32

## What is charge per unit area σ?

###
It's charge distribution on the surface.

dq= σ dA

33