Equations

Question 1

Coulomb Force

Answer 1

• F_12 = (q_1 q_2)/(4πϵ) x (r2 - r1)/r^3

Question 2

Electric Field

Answer 2

E = (q/4πϵ) x (r - rq)/(r^3)

Question 3

Electric Dipole Moment

Answer 3

p = qd

Question 4

Torque on electric dipole

Answer 4

t = p x E

Question 5

Electric Flux through flat surface

Answer 5

Φ = E · A

Question 6

Electric Flux INtegral

Answer 6

Φ = ∯E· dS

Question 7

Gauss’s Law

Answer 7

∯E· dS = Q/ϵ

Question 8

Work Done and Potential Energy

Answer 8

W = ∫F · dl = -ΔU

Question 9

Potential Energy between 2 point charges

Answer 9

U = qq/4πϵr

Question 10

Electric Potential of a point charge

Answer 10

V = q/4πϵr

Question 11

Capacitance

Answer 11

C = Q/V = ϵA/d

Question 12

Energy stored in a capacitor

Answer 12

U = QV/2

Question 13

Energy density of an electric field

Answer 13

u = (ϵE^2)/2

Question 14

Current Density Vector

Answer 14

J = I/A

Question 15

Lorentz Force

Answer 15

F = q(E + v x B)

Question 16

Magnetic Flux

Answer 16

Φ = ∬B · dS

Question 17

Solenoid Condition

Answer 17

∯B · dS = 0

Question 18

Force on a current carrying wire

Answer 18

dF = IdL x B

Question 19

Magnetic Dipole Moment

Answer 19

μ = IA n

Question 20

Torque on a current loop

Answer 20

t = μ x B

Question 21

Biot Savart Law

Answer 21

B = (μq/4π) (v(t) x (r - r(t))) / |r -r(t)|^3

Question 22

Magnetic Field of a straight wire

Answer 22

B = (Iμ0/2πR) φ

Question 23

Ampere’s Law

Answer 23

∮B · dL = μ0 I

Question 24

Magnetic Field of a solenoid

Answer 24

• Outside = 0
• Inside = μ0 I n z

Question 25

Faradays Law of induction

Answer 25

ϵ = -(dΦ)/(dt)

Question 26

Self Inductance

Answer 26

L = NΦ/I

Question 27

Flux Linkage

Answer 27

NΦ

Question 28

Emf of self inductor

Answer 28

ϵ = -L (dI/dt)

Question 29

Energy stored in a inductor

Answer 29

U = (LI^2)/2

Question 30

Impedance of a Resistor

Answer 30

Z = R

Question 31

Impedance of a capacitor

Answer 31

Z = 1/(jwC)

Question 32

Impedance of an inductor

Answer 32

Z = jwL

Question 33

Electric Field from Potential

Answer 33

• E = - gradient of V

Question 34

Capacitor Discharging Equations

Answer 34

• A = A0 x e^(-t/RC)
• A is Q, V and I
• I is same for charging and discharging

Question 35

Capacitor Charging Equations

Answer 35

• A = A0 (1 - e^(-t/RC))
• A is Q and V
• I is same for charging and discharging

Question 36

Faradays Law of Induction Relation with electric fields

Answer 36

ϵ = -dϕ/dt = ∮E·dl

Question 37

Potential (difference) from Electric Field equation

Answer 37

Va - Vb = ∫E ·dl