What is Induction: Definition and 999 Discussions

Mathematical induction is a mathematical proof technique. It is essentially used to prove that a statement P(n) holds for every natural number n = 0, 1, 2, 3, . . . ; that is, the overall statement is a sequence of infinitely many cases P(0), P(1), P(2), P(3), . . . . Informal metaphors help to explain this technique, such as falling dominoes or climbing a ladder:

Mathematical induction proves that we can climb as high as we like on a ladder, by proving that we can climb onto the bottom rung (the basis) and that from each rung we can climb up to the next one (the step).
A proof by induction consists of two cases. The first, the base case (or basis), proves the statement for n = 0 without assuming any knowledge of other cases. The second case, the induction step, proves that if the statement holds for any given case n = k, then it must also hold for the next case n = k + 1. These two steps establish that the statement holds for every natural number n. The base case does not necessarily begin with n = 0, but often with n = 1, and possibly with any fixed natural number n = N, establishing the truth of the statement for all natural numbers n ≥ N.
The method can be extended to prove statements about more general well-founded structures, such as trees; this generalization, known as structural induction, is used in mathematical logic and computer science. Mathematical induction in this extended sense is closely related to recursion. Mathematical induction is an inference rule used in formal proofs, and in some form is the foundation of all correctness proofs for computer programs.Although its name may suggest otherwise, mathematical induction should not be confused with inductive reasoning as used in philosophy (see Problem of induction). The mathematical method examines infinitely many cases to prove a general statement, but does so by a finite chain of deductive reasoning involving the variable n, which can take infinitely many values.

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  1. T

    Why velocity affects electromagnetic induction?

    I understand that electromagnetic induction is determined because of a moving electric charge in a magnetic field, but why is the motion necessary? Why is it that motion causes electromagnetic induction and it isn't possible without motion?
  2. P

    Mathematical induction question

    Homework Statement Suppose a and b are real numbers with 0 < b < a. Show that, if n is a positive integer, then a^n - b^n \leq na^{n-1}(a-b) Homework Equations The Attempt at a Solution I'm trying to show this by induction. Let P(n) be the proposition that a^n - b^n \leq na^{n-1}(a-b)...
  3. F

    Conceptual Question: Light VS Electro-Magnetic Induction

    I'm willing to say that I have a fair understanding of Electromagnetism, at least from a classical perspective, but I was never entirely clear about the difference between, say, the time-varying magnetic field created by an inductor and the Electromagnetic field of light in general. Based on...
  4. J

    How Do You Prove a Sigma Notation Equality Using Induction?

    Homework Statement 2n-1 Sigma (3i+1) = n(6n-1) i=0 prove for all positive n Homework Equations The Attempt at a Solution It holds true for n=1 5=5 then P: m+1 2m+1 Sigma(3i+1) = (m+1)(6(m+1)-1) or 6m^2 + 11m + 5 i=0 then 2m+1 Sigma(3i+1) = m(6m-1) +...
  5. R

    Chebyshev polynomial - induction problem

    Homework Statement Let Tn(x)=cos(narccosx) where x is real and belongs to [-1,1] and n E Z+ Find T1(x). Show that T2(x)=2x^2 - 1. Show that Tn+1 (x) + Tn-1 (x) = 2xTn(x) Hence, prove by induction that Tn(x) is a polynomial of degree n. The Attempt at a Solution Since cosθ=x and arccosx=θ we...
  6. P

    Mathematical Induction (The inductive step)

    1. I don't understand how to prove this. for all n≥1, 10n - 1 is divisible by 9. 3. I've done the basis step. Now I'm on the inductive step. I'm using (10k+1-1)/9=1. I don't know where to go from there. Using algebra just gets me down to 10k+1= 10. And I really don't think that's...
  7. F

    LHS = (p+1)^2 + (p+1) = p^2 +2p +1RHS= 2^(p+1) = 2^p *2 = 2(p^2 + p)

    Prove by induction that n^2 + n ≤ 2^n for all integers n≥5 How i did: Case(1) Suppose that n = 5 LHS = 5^2 +5 = 30 RHS = 2^5 = 32 30 ≤ 32 Ok LHS ≤ RHS Case (2) Suppose that's true for n=p≥5. Show that its true for n = p+1 What should i do next ? I had a memory loss here :(
  8. L

    Stuck with a simple induction problem

    Suppose you are building a sequence consisting of 0 and 1 in such a way that: - you start with 1 - no consecutive 0s are allowed Examples of such sequences are: 1, 1010, 110111101 etc. Empty sequence is also allowed. I want to prove by induction that the number of 0s in such a sequence is...
  9. M

    Proving a Series by induction

    Homework Statement ( Given: U0=2 and : (U)n+1=(Un^2+Un)/(1+Un) Homework Equations prove that for every n in N : Un>1 The Attempt at a Solution ok for n=0 i got Un+1=2 and 2>1 therefore for n=0 its true. now we assume its true for U=0 and we want to show that Un+1>Un...
  10. Y

    Circuit Analysis current and induction

    Homework Statement The Attempt at a Solution I'm not really sure where to start with this one. I know that in steady state the capacitor will become an open circuit and the inductor a short circuit. I first changed the current source to a thevenin equivalent of 1.2mV. I don't...
  11. M

    Proving the Inductive Relationship for the Gamma Function

    Homework Statement Prove by induction that gamma(v+1)(v+1)(v+2)...(v+k)=gamma(v+k+1) for k=1,2,3... Homework Equations Really just using the relation x*gamma(x)=gamma(x+1) The Attempt at a Solution for a basis gamma(v+1)(v+1)=gamma(v+1+1) so holds for k = 1 inductive...
  12. Telemachus

    Magnetic induction for a tesla flat spiral coil

    Hi there. I have a current I running throught a tesla spiral coil, and I have to compute the magnetic field at the center of it. The tesla coil has N turns, and an inner radius a, and outer radius b. This is the tesla spiral coil: The courrent enters through the outer cable, and goes out...
  13. N

    Earth wire position and charging by induction

    Hello! Not sure if this should go here, but it's from a physics textbook. I was reading about charge by induction and the use of an Earth to achieve this. Here's a wonderfully detailed and exquisite image that took many laborious hours to construct. The red and black Earth's are not intended...
  14. D

    How can I prove that n^3 + (n+1)^3 + (n+2)^3 is a multiple of 9?

    Hello everybody, I am doing my reading lately to prepare for some exams to join a mathematics department. And I would very much like, if anyone could help, the solution (or a hint) to the following induction proof. " Show that n^3 + (n+1)^3 + (n+2)^3 is a multiple of 9 " :smile: I...
  15. X

    Electromagnetic induction problem

    Homework Statement http://dc10.arabsh.com/i/03594/qn9gr42q192z.png What is the direction of current in ring 2 if : a) ring 2 moves towards ring 1 b) ring 2 moves away ring 1 The Attempt at a Solution I used Fleming right hand rule but I'm not sure if it is true, a) the...
  16. V

    Can countability affect the application of induction?

    I remember my discrete math course in university, where professor told that we can apply induction only to discrete sets. Yet, neither Wikipedia nor Google say nothing about countability importance for induction. They say that underlying set must be well-ordered. The well-ordering topic says...
  17. S

    Induction Furnace: Minimizing Downtime & Solutions

    Hello Can you please assist to obtain information, as explained and requested below: We are trying to minimize downtime for failure of induction furnace lining and hence we are exploring all possible ways and means to achieve the same. The situation in our plant has...
  18. Y

    Induction Cooking, skin effect, hysteresis losses

    I've been looking into the induction heating a bit lately and have come up with a few questions. One is in regards to hysteresis losses. I know what hysteresis is and how it contributes to the heat generation, but how much of an effect does it actually have? Some articles I've read have...
  19. Z

    Mathematica Hard mathematical induction question

    Hi everyone, I have been trying to do this induction question... but can't seem to understand how to do it. Prove by induction that, for all integers n is greater than or equal to 1, (n+1)(n+2)...(2n-1)2n = 2^n[1x3x...x(2n-1)] This is what someone else has given as the answer: For n...
  20. A

    Working of induction generator

    Suppose that the stator of an induction motor is connected to grid and the rotor is run faster than the synchronous speed. Now the current direction in the rotor circuit reverses because air gap flux as seen by the rotor rotates in reverse direction at slip speed. To maintain the same flux in...
  21. 0

    Electromagnetics (Difference in self induction in AC and DC)

    Hello folks. I have an electromagnetics quiz tomorrow and I am kind of nervous. I can't seem to grasp the concept of induction, more importantly how it differs in AC and DC circuits. So in lay terms: Induction is production of electric current across a conductor which is moving through or...
  22. A

    Computer Simulation of Wireless Induction?

    I was just wondering if anyone knew of software that would allow me to simulate magnetic induction. I'm researching into the effects distance and the number of windings has on the effect of transfer efficiency between two coils. I've seen lots of people mention Maxwell, but they seem to...
  23. 3

    Prove False: n\geq a\Rightarrow n!\geq a^n

    I will prove the false statement, that n\geq a\Rightarrow n!\geq a^n, n\in \mathbb{N}-\left \{ 0 \right \} with induction For n=1 1\geq a\Rightarrow 1!\geq a^1\Rightarrow 1 \geq a which is true. Suppose that n\geq a\Rightarrow n!\geq a^n, n\in \mathbb{N}-\left \{ 0 \right \} Then...
  24. P

    Induction heating theory clarification

    Hi all, I'm trying to understand induction heating, specifically if there can be inductive heating without a coil, simply power applied through a hairpin-shaped resistor. Imagine a big hair-pin-shaped resistor with power applied to one leg - near the bottom of these legs are small metal...
  25. N

    Proving a Polygon's Diagonal Formula with Induction | Step-by-Step Guide

    Homework Statement Prove by induction that a polygon with n angles has Mn = (n-3)n/2 diagonals. Homework Equations We assume that the formula Mn+1=Mn +n - 1 is correct. The Attempt at a Solution First of all I checked if the 1st formula is correct for n=3 (a triangle)...
  26. S

    Mutual Induction of a solenoid and a coil

    Homework Statement A single-turn circular loop of radius R = 0.235 m is coaxial with a long 1780 turn solenoid of radius 0.0435 m and length 0.850 m, as seen in the figure below. The variable resistor is changed so that the solenoid current decreases linearly from 6.12 A to 1.46 A in 0.230...
  27. T

    Principle of induction problem

    Homework Statement Let x ∈ N. Show that there exists for each n ∈ N a natural number denoted by x^n (this is just a notation, but should tell you what we are doing)such that x^1 =x and x^σ(n) =x·x^n. Homework Equations σ(n) = n + 1 The Attempt at a Solution So far my answer is...
  28. S

    Mutual Induction of a solenoid and a coil

    Homework Statement A single-turn circular loop of radius R = 0.235 m is coaxial with a long 1780 turn solenoid of radius 0.0435 m and length 0.850 m, as seen in the figure below. The variable resistor is changed so that the solenoid current decreases linearly from 6.12 A to 1.46 A in 0.230...
  29. G

    Show by induction that (1-nu)(1+u)<=1 for n=0,1,2,3 and u>-1

    Hi, I have to solve this problem... I have done something, but I don't know if it is right :/ Thanks a lot for your help! "Show by induction that (1-nu)(1+u)<=1 for n=0,1,2,3... and u>-1" For n=0: (1-0*u)(1+u)^0 <=1 1*1<=1 1<=1, which is true. Assume that the statement is true for...
  30. 1

    Is this induction proof valid?

    Homework Statement My induction proof was really easy and simple, and people were having problems and doing substitutions and other complicated things. Normally I'd take pride in making a simpler proof but, there are really brilliant people in this class and I'm just starting to get the...
  31. A

    Induction motor fed from rotor.

    What will happen if an induction motor is fed from rotor side. I mean if i supply say 50HZ frequency supply to rotor through slip rings and have my stator windings connected to variable resistances will the rotor start to rotate and if it does in which direction?
  32. T

    Induction heating of a cylinder

    Hello! I am making som calculations on induction heating of a metallic cylinder inside a solenoid through which an AC current passes, but the answer I get seems to be completely unrealistic (10 kW with a 50 Hz, 5 Amps, 230 V rms), but I can't seem to find my mistake. What I think is...
  33. Darth Frodo

    Can You Charge Something Negatively Through Induction?

    This isn't a homework question as such, but according to my physics book in electricity it is always the negative (electrons) charge that move. Is it possible to charge something negatively via induction? I mean the last step in the process is earthing the object, if you Earth it, do positive...
  34. J

    Exploring Electromagnetic Induction in Coils: The Impact of Magnet Placement

    Homework Statement When we place a magnet in a long coil of wire the emf will be maximum when the magnet is at either end. What would happen when the magnet lies in the middle of the coil (i.e: the same amount of flux is interacting with the coil at all times). Would we have an induced EMF...
  35. S

    General strong induction question

    Homework Statement I have been studying induction for a few days now and am able to produce some proofs, but have some inquiries as to its theory. First, in strong induction, it seems that different sources disagree on whether base cases are necessary to include within the proofs. Is there...
  36. O

    Proof by Induction: Proving S_n = 1/(2n)

    Homework Statement For each positive integer n, let S_{n} = \frac{1}{n(n+1)} + \frac{1}{(n+1)(n+2)} + ... + \frac{1}{(2n-1)2n}. (a) Calculate S_{1}, S_{2}, S_{3}. Then use this data to guess a simple formula for S_{n}. (b) Prove your guess in part (a) by mathematical induction (c) Use Result...
  37. H

    Mathematical Induction Problem: Finding a Formula for a Sequence of Numbers

    Homework Statement Okay, so I'm going to be completely honest, I am really bad at math, and I have been struggling the past couple of weeks in my Quantitative Reasoning class. I am so lost. I don't know if it's my teacher's teaching method or what, but nothing is clicking for me at the moment...
  38. M

    Proving Sn=(-1)^n(n+1) for Induction | Homework Solution

    Homework Statement Sn=1-3+5-7...+(-1)^n(2n+1)Homework Equations Show that Sn=(-1)^n(n+1) The Attempt at a Solution S(n+1)=Sn+(-1)^(n+1)*(2n+3) = (-1)^n*(n+1)+ (-1)^(n+1)*(2n+3) S(n+1)= (-1)^(n+1)*[(2n+3)-(n+1)] (because (-1)^(n+1)= - (-1)^n ) S(n+1)=(-1)^(n+1)*(n+2) is that correct proof
  39. I

    Arranging numbers problem (induction)

    hi Here is a problem I am trying to do .. Show that it is possible to arrange the numbers 1, 2, . . . , n in a row so that the average of any two of these numbers never appears between them. Here is my attempt. The base case will consist of first two numbers. So Base Case: n=2 The...
  40. R

    How to Resolve Errors in Proof by Induction for a Factorial Ratio?

    Homework Statement So we have to prove that \frac{(n+1)(n+2)(n+3)...(2n)}{1*3*5...*(2n-1)} = 2n2. The attempt at a solution I. For n=1, obviously the proposition is true. (2*1/(2-1) = 2^1 = 2) II. Let n=k and assume \frac{(k+1)(k+2)(k+3)...(2k)}{1*3*5...*(2k-1)} = 2k. Now, for n=k+1 we...
  41. M

    Proving 8 divides 1+2x3^(n-1)+5^n for all n>0

    Homework Statement Prove that 8 divides: 1+2x3^(n-1)+5^n for every natural number : n>0Please I'm having difficulties solving this problem, i just want to understand the concept of how to solve it thank you. I know that 8 divides: 1+2x3^(n-1)+5^n can also be written as 1+2x3^(n-1)+5^n=8k ...
  42. W

    Induction coil powering a crt: how does it work?

    A professor the other day used an induction coil power a crt tube like the one at the link below. http://chemteacher.chemeddl.org/services/chemteacher/index.php?option=com_content&view=article&id=99 I understand the general idea of both induction coils and crts, but what confuses me is...
  43. H

    How to apply Faraday's Law of Induction

    Greetings, I have read the explanation on this forum here: https://www.physicsforums.com/showthread.php?t=441637 which discusses Faraday's Law of Induction, but I'm having a hard time understanding how to extrapolate that to my problem. My goal: Construct a circuit that measures ambient...
  44. E

    Electromagnetic Induction Question

    Can someone please tell me why the magnetic field makes the electrons flow round the coil in a generator? Does the force of the magnetic field have to go in the same direction as the coil?
  45. 1

    How can we use induction to prove that 2^{2n-1} + 3^{2n-1} is divisible by 5?

    Homework Statement 2^{2n-1} + 3^{2n-1} is a number divisible by 5. Prove by induction. Homework Equations The Attempt at a Solution Firstly, solving for n = 1 is true. I've re-written the statement to be: 2^{2n-1} + 3^{2n-1} = 5L where L is any natural number...
  46. P

    Divisibility of (n^2)! by (n!)^n+1: Proven Through Induction

    show (n^2)! is divisible by (n!)^n+1 base case 1 divides 1 so I did the induction and got (n^2+2n)!=((n+1)^n * (n!) *(n!)^n+1 (n^2+2n)*...*(n^2)!=((n+1)^n * (n!) *(n!)^n+1 can we conclude that (n^2)! is divisible by (n!)^n+1 for all n from there because we have the bold...
  47. O

    Proof by Induction - Inequalities

    Homework Statement Prove by induction that: (Please see attachment) Homework Equations The Attempt at a Solution Can someone please confirm if I have worked the question out correctly. Many thanks.
  48. J

    Why Does EMF Change as a Magnet Passes Through a Coil?

    Homework Statement If I take a magnet and drop it though coil then the graph would have an increasing voltage until a maximum and then a reducing emf (until 0) and then a further reducing emf until a minimum and then an increasing emf again graph looks like this...
  49. S

    Proofs by induction on immediate predecessors (well-formed formula complexity)

    Hi physics forum, I have no idea where to start with this: As far as I know the general pattern for this sort of proof is, 1) All atomic well-formed formulas (wffs) have some property P 2) From the assumption that immediate predecessors of any non-atomic wff A have P, so too does A...
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