Laws & Equations

Question 1

Faradays Law:

Answer 1

The magnitude of the EMF Is directly proportional to the rate of change of flux (Applies to generators)

Question 2

Lenz’s Law:

Answer 2

An inducedelectric currentflows in a direction such that the current opposes the change that induced it

Question 3

Kirchhoff’s Voltage Law

Answer 3

The sum of the voltage drops around a single closed path equals the sum of the voltage sources

Question 4

Kirchhoff’s Current Law

Answer 4

At any point in an electrical circuit, the sum of currents flowing towards that point is equal to the sum of currents flowing away from that point

Question 5

Ohms Law

Answer 5

V=IR

Question 6

Power Law

Answer 6

P=IV

Question 7

Left hand rule

Answer 7

Electric motors

Question 8

Right Hand rule

Answer 8

Electric Generators

Question 9

EMF Equation

Answer 9

EMF = BLV

B = Magnetic Field 
L = Length of the object moving 
V = Speed

Question 10

Conductance Equation

Answer 10

Conductance (G) = 1/R

Question 11

Internal resistance equation

Answer 11

Internal resistance = OCV - CCV
-—————
I

Question 12

Power Equation’s

Answer 12

P = I^2 x R

P = V^2/R

P = V x I

P = Amps x Volts

Question 13

1 watt =

Answer 13

1 Joule per second

Question 14

Charge (Q) Equation:

Answer 14

Q = Capacitance x Voltage

Question 15

Time constant Equation:

Answer 15

5 x R x C

Question 16

MMF Equation:

Answer 16

MMF = Amps x Turns

Question 17

Capacitance Equation:

Answer 17

C = KA/d

KA = Dielectric Constant 
d =  Distance plates apart

Question 18

Field Strength Ident.

Answer 18

H

Question 19

Flux Density Ident.

Answer 19

B

Question 20

Field Strength Equation:

Answer 20

H = I x N / L

I = Current
N = Number of turns 
L = Length

Question 21

Magnetic Flux density (B) Eqution

Answer 21

B = H x permeability

H = Magnetic field Strength

Question 22

Magnetic Flux equation

Answer 22

Flux = B x A

A =  Pole Area 
B = Flux density

Question 23

Power in a motor equation:

Answer 23

Torque x 2pi x rev/sec

Question 24

Torque equation:

Answer 24

Force x radius

Question 25

Permeability equation

Answer 25

Permeability = flux density / magnetic field strength

Question 26

Average voltage =

Answer 26

Average voltage = 0.63 x peak value

Question 27

True power =

Answer 27

TP = V x I x PF

Question 28

Form Factor =

Answer 28

Form factor = RMS/Average

Question 29

RMS =

Answer 29

RMS = Peak voltage x 0.707

Or

RMS = peak voltage / 1.414

Question 30

Energy stored in a capacitor =

Answer 30

0.5 x C x V^2

Question 31

Inductive Resistance =

Answer 31

2 Pi x frequency x inductance