Induction Definition and 999 Threads

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.

View More On Wikipedia.org
  1. D

    Building an Induction Heater for Steel & Aluminium

    Hi guys I'm looking to make an induction heater to heat bits of steel and aluminium (maybe 15mm by 25mm). Can anyone recommend a good source of information in terms of calculating the various parameters and other general information? I've looked at many websites but a lot of them seem to...
  2. F

    Positive Charge Induction on Insulating Sphere

    Homework Statement By what method will a positively charged rod produce a negative charge on a conducting sphere that is placed on an insulating surface. Homework Equations a) by means of conduction b) by means of induction c) by means of convection d) none of the choice are correct...
  3. K

    What Is the Direction of Current in a Loop Near a Current-Carrying Wire?

    Homework Statement You are holding a conducting loop of copper and looking at its circle. Behind it is a long current-carrying wire carrying the current from left to right. As you pull the loop toward you, what is the direction of current flow if any? A)No way to tell B)Counter-clockwise...
  4. M

    What Causes Rotation in a Non-Rotating Magnet?

    If a permanent magnet is moved in a direction at right angles to the magnet field lines in the magnet, is an emf produced across the magnet? Mike
  5. H

    Mathematical induction problem solving question help

    hi this question i just cannot do. i have no idea where to start: a student is trying to recall the formula for the sum of cubes of consecutive numbers. she thinks it may be (n^3(n+1)^3) /8 or (n^2(n+1)^2)/4 . show by counter example one is incorrect and the other is correct by induction...
  6. K

    How Does Grounding Affect Charge Distribution in Nested Spherical Shells?

    Hi, I'm a physics student, preparing for an exam (it happens to be tomorrow heh), and I'm having trouble with induction of conductors. I need to get it right so i can solve more difficult problems, but the more i try the worse it gets. Basically i'd like to know how things work in sets of shells...
  7. E

    Faraday's Law of Induction: Why is EMF Inversely Proportional to Time?

    Hi, I am doing coursework on Faraday's law of induction. My assignment was to carry out experiments which confirm Faraday's law and also to explain the physics of how faraday's law works... My experiments all worked perfectly, producing straight line graphs showing that: \epsilon\propto N...
  8. G

    Discrete Math Question ( not really homework) about strong induction

    For some questions strong induction would test for cases n+1, n+2 and for other n+1,n+2,n+3, or other ways, why is that? Here's two examples Suppose that the only paper money consists of 3-dollar bills and 10-dollar bills. Find what dollar amounts can be made from a combination of these...
  9. F

    [LOGIC] Proof by Induction in Peano Arithmetic

    I have to do the following using these axioms PA1-7, the others below it are previously proved results I can use too. [Sa] means the successor of a. Base Case: y = S0 x.S0 = S0 → x.0 + x = S0 → 0 + x = S0 → x = S0 & y=S0 Now the induction step is usually y=a to y=Sa, however this does...
  10. T

    Induction with sum on left and right side.

    Homework Statement Does \sum_{k=1}^{n}(\frac{1}{2k-1} - \frac{1}{2k}) = \sum_{k=1}^{n}\frac{1}{k + n} hold for 1 \leq n Homework Equations The Attempt at a Solution It holds for n = 1. I assume that it should be done with induction but I can't find a way actually compare the...
  11. H

    What really causes electromagnetic induction/ the motor effect?

    When a conducting wire is subjected to a changing magnetic field, what causes the electrons in this wire to move? Conversely, why does the movement of current in the wire (with a non-'moving' magnetic field) cause the wire to move? I understand these phenomena macroscopically (and that they...
  12. teroenza

    Prove by Induction the 11^(n+1)+12^(2n-1) is dvisible by 133.

    Homework Statement Prove by Induction the 11^(n+1)+12^(2n-1) is visible by 133. For all n>1 or n=1 Homework Equations The Attempt at a Solution I have shown that the base case of n=1 holds. Then I assumed that the original statement "11^(n+1)+12^(2n-1)is divisible by 133"...
  13. S

    Induction proof (solution included but still confused).

    Homework Statement The problem (and its solution) is attached as Problem.jpg. Homework Equations Base case, induction hypothesis, and induction step. The Attempt at a Solution I see that the base case is correct and I also see how everything under "Proof:" is done algebraically. As...
  14. L

    Help with a large induction coil secondary

    I am about to build an induction coil in the traditional manner, after "A. T. Hare". The dimensions intimated in the book are confusing and imply there are 96 pies 3/16" each or 18" long - this is the length of the core, and the book indicates around 13" between ends of coils. The book also...
  15. G

    Proving Principle of Complete Induction from Ordinary Induction

    Homework Statement Prove the principle of complete induction from the ordinary principle of induction. Hint :- if A contains 1 and A contains n + 1 whenever it contains 1,2,...,n consider the set B of all k such that 1,2,...,k are all in A Homework Equations Principle of mathematical...
  16. 1

    Induction and Recursion I have NO idea

    I think I'm pretty good at standard induction. Never had a problem. Induction and recursion is mercilessly whooping my ***. Homework Statement Let a1 = 1. For each natural number n > 1, let an = 3an-1 - 1. Prove that for each natural number n, an = 1/2(3n-1 + 1) Homework...
  17. E

    Induction Proof: Am I on the right track?

    Homework Statement Let a(1)=a(2)=5 and a(n+1)=a(n)+6a(n-1), n≥2 Use induction to prove that a(n)=(3^n)-(-2)^n for n≥1 Homework Equations Not applicable The Attempt at a Solution I have check that a(3) = 5+6·5 = 35 = 3^3-(-2)^3 so it holds for n = 3. The cases n = 1 and n = 2...
  18. S

    Electromagnetic Induction Lab. Magnet through a coil

    I apologize in advance if some of my answers don't quite make sense. I'm generally articulate, but not when it comes to physics I'm barely grasping. I did a lab and part of it was dropping a magnet through a coil, which produced a Voltage vs Time graph using LabPro. For trial 1 we had the N...
  19. P

    Calculating Average Induced EMF in a Rotating Coil

    Homework Statement A flat coil of wire has an area of 0.010 m2and contains 100 turns. Initially the coil is oriented so that the normal to its surface is parallel to a downward constant magnetic field of 0.2 T. The coil is then rotated clockwise through an angle of 30oin a time of 0.10 s...
  20. I

    Proving inequality with mathematical induction

    I am having trouble proving these. I cannot figure out how to get to the conclusion. Here is my attempt. The stuff in red is just side work and is not part of the proof. I always get stuck on these types of problems, can someone offer some tips on how to approach these kind of problems in...
  21. S

    Proof by induction: 5^n + 9 < 6^n for all integers n≥2

    Homework Statement Prove the statement by mathematical induction: 5n + 9 < 6n for all integers n≥2 Homework Equations .. The Attempt at a Solution Proof: let P(n) be the statement, 5n + 9 < 6n P(2) is true because, 34<36. Suppose that P(n) is true. P(n+1) would be...
  22. P

    Electromagnetic Induction and an electric generator

    Homework Statement An electric generator consists of n = 500 turns of wire formed into a rectangular loop with a length of 5 cm and width of 3 cm placed in a uniform magnetic field of 2.50 T. What is the maximum value of the emf produced when the loop is spun at f = 100 rpm about an axis...
  23. L

    Understanding Mathematical Induction: Clarifying Starting Points and Examples

    Hi, Some times the starting point in MA confuses me, for example (\sum_{i=1}^ni)^2=\sum_{i=1}^ni^3 have we start with 2 or it is enough to show it when n=1 Thanks in advance.
  24. M

    Electromagnetic induction question, includes solenoids

    Homework Statement This isn't a homework problem but I am very curious. How much voltage can a magnetic, about the size of a fist, generate by passing through a solenoid with about 3 loops every centimeter with being pulled by a tension of 1000 N over a distance of 2 meters...
  25. T

    Proving the Sum of Reciprocals by Induction

    Hello there, I'm having trouble proving this by induction Homework Statement \frac{1}{1(2)} + 1\frac{1}{2(3)}+...+\frac{1}{n(n+1)} = \frac{n}{n+1} Homework Equations For the base case n=1 \frac{1}{1(2)}=\frac{1}{1+1} = \frac{1}{2} = \frac{1}{2} \frac{k}{k+1} +...
  26. P

    Electrostatic induction in Solutions?

    I was wondering if induction can apply to different chemical solutions. Take HCl for example. If a negatively charged rod were placed against the beaker in which HCl was held, would the H+ ions be pulled towards the rod. Would the same outcome appear in a neutral solution of NaCl (drawing the...
  27. S

    Electromagnetic induction open cuircuit and how to determine direction

    When a magnet is pushed into a solenoid an induced emf occurs. So if it is a closed circuit then an induced current will flow. But if it is an open circuit then an emf will still be induced but no current this time. So will any poles be formed to repel it? What do they mean by the current...
  28. S

    Why Does EMF Cancel Out When a Magnet Moves Constantly Inside a Solenoid?

    What will happen when I push a magnets into a solenoid with constant speed throughout? I understand that when the magnet leaves and enters an induced emf will occur, but in the middle no emf will occur. Why is this so? I thought that the magnetic flux linkage changes as it moves in the solenoid?
  29. X

    Proof by induction problem explanation

    In this link (https://www.physicsforums.com/showthread.php?t=523874 ) there's an example of proof by induction. Somewhere in the explanation there's the phrase: Why they decided to multiply both sides by x+1?
  30. D

    Proof By Induction: Fibonacci Sequence

    Homework Statement \sum_{i=0}^{k} {k \choose i}f_{n+i} = f_{n+2k} Homework Equations Definition: f(0)=0 ; f(1)=1 f(n)=f_{n-1} + f_{n-2} for n>=2 The Attempt at a Solution I searched a basis for which the statement is true: n=2 and k=1 \sum_{i=0}^{1} {1 \choose i}f_{2+i} =...
  31. I

    Proof by Induction: Explained for Confused Readers

    I am confused by what the book is saying, can someone explain how they got the thing I circled in red?
  32. W

    Mathematical Induction question

    A question I'm working on and my math book doesn't clarify the answer well enough for me to follow. I'm having some issues at getting the math symbols to work correctly so bare with me!Prove by mathematical induction that if A1, A2, ..., An and B are any n + 1 sets, then: Base step = n = 1 so...
  33. H

    Electrostatic induction in a conductor should be immpossible

    i can't grasp the idea that how is electrostatic induction possible in a conductor. for example, if a negatively charged strip is brought near a metal conductor, the electrons will be repelled to the further end of the conductor thus making the end near the charged rod positively charged...
  34. M

    Convergence Induction for Positive Sequences: Proving Limit Behavior

    Homework Statement If (an) — > 0 and \bn - b\ < an, then show that (bn) — > b Homework Equations The Attempt at a Solution
  35. B

    How can tuning a coil with a capacitor help detect multiple metal objects?

    Good Day All, I would like to know if anyone can help with the following; I am running it a few problems and I am not able to find the formulas that will allow me to prove my idea. I have a loop of 20 Gauge magnet wire; it's 24 inches by 2 inches. I'm using this as a detector, but i want to...
  36. T

    Proving sets with structural induction

    Consider the set S defined recursively as follows: • 3 ∈ S, • if x,y ∈ S,then x−y∈S, • if x∈S, then 2x ∈ S, • S contains no other element. Use Structural Induction to write a detailed, carefully structured proof that ∀ x ∈ S, ∃ n ∈ Z, x = 3n. What I've got is since 3 is in the set...
  37. S

    Heating frozen water pipes by induction?

    I have a mountain cabin where 2 water pipes, hot an cold, goes between the bathroom and kitchen. However, they tend to freeze in the winter. The obvious solution is to put a heating wire along the pipes, but access is cumbersome. So I have thought about following solution: I ensure electrical...
  38. T

    Can Structural Induction Prove All Elements of Set T Are Powers of 2?

    Consider the set T defined recursively as follows: • 2∈T, • if x∈T and x>1,then x/2 ∈T, • if x∈T and x>1,then x^2 ∈T, • T contains no other element. Use Structural Induction to write a detailed, carefully structured proof that ∀ x ∈ T, ∃ n ∈ N, x = 2n. I'm not sure how to...
  39. M

    How much power is needed to melt aluminum using induction heating?

    How much power is needed to be able to melt aluminum using induction heating? So I have coil of copper wire around an aluminum cylinder. The aluminum is NOT touching the copper wire. the copper wire have a thickness of 0.5 cm. d = 0.5cm the copper wire is looped 20 times around. N = 20...
  40. D

    Efficiency of domestic induction heater

    What is the heating efficiency of a domestic induction heater as compared to a simple electrical heater and microwave oven? Please give comparison on the basis of Kilowatt hour consumed.
  41. H

    How can induction be used to prove a sum of cubes formula?

    Hi guys, Long time lurker of this forum, but first time poster. Discrete Math is going to be the end of me; I'm just not understanding how to solve problems and write the proofs. Any help would be greatly appreciated. Thanks in advance. The Problem: Let nεZ≥1. Show that...
  42. I

    Proving the Recursive Formula for an Using Induction

    Homework Statement Define an = (an-1 + an-2)/2 for each positive integer ≥ 2. Use induction to show that: an+1 - an = (-1/2)n(a1 -a0) Homework Equations First show it is true for base case. Assume if it is true for (k), then show it is true for (k + 1). The Attempt at a Solution...
  43. D

    Deriving the Identity: (1+2+3+...+n)^2 = 1^3 + 2^3 + 3^3 +...+ n^3

    Solved: Is this an induction problem? (1+2+3+ \cdots + n)^2 = 1^3 + 2^3 + 3^3 + \cdots + n^3 , n \ge 1 Provide a derivation of the identity above. I do not know how to begin this problem. I tried to use induction but did not succeed. Also, I honestly do not know what it means by...
  44. D

    Electromagentic Induction Sinusoidal Wave Help

    When you have a magnet moving up and down a coil. The magnet cuts the field lines. Which generates an AC current in the coil. In my exam, there was a sinusoidal curve showing the generation of AC current. When the curve crossed the x-axis, that point was labelled X. Now at that point was the...
  45. F

    Simplifying Mathematical Induction for Sequences Using Algebra

    I have an idea of what to do and I have reached the stage but when i am at final stage- I am struggling to simplify as i simply don't understand (1/2)+(2/2^2) +(3/2^3)+...+ (n/2^n) = 2 - (n+2/2^n) so I have done p(k) and p(k+1) this gives me p(k) (1/2)+(2/2^2) +(3/2^3)+...+ (k/2^k)...
  46. R

    How much current/voltage on average is produced by means of induction?

    By spinning a magnetic field in the presence of conducting wire, how much voltage/current is produced? Thanks.
  47. S

    Induction to prove an expanded integral

    Homework Statement \int_0^1{x^n (1-x)^r}\,dx = \frac{n!}{(r+1)(r+2)...(r+n+1)} Homework Equations n≥0, r≥0 The Attempt at a Solution i solved it for the case n=0, where RHS and LHS are the same. however, I am having trouble integrating the LHS for the induction step where n=k+1. i'm trying...
  48. G

    Prove a^(m+n) = a^m + a^n with mathematical induction

    prove by induction that, 1) a^(m+n) = a^m + a^n 2) (a^m)^n=a^(mn) 2. Homework Equations -- mathematical induction 3. The Attempt at a Solution the equations hold for a = 1. let's say the equation hold for a = s; then s^(m+n) = s^m + s^n now for a = s+1; (s+1)^(m+n) = (binomial expansion of...
  49. T

    Induction of emf in moving conductors in magnetic fields

    In preparation for an upcoming physics exam I have been going through some past paper questions. This question is from the multiple choice section of the paper, so while I can check the answer there is no source from which I can see it being worked through. Homework Statement An aircraft...
  50. F

    Negative Voltage/Current Readings in Induction Generator: Causes & Solutions

    Homework Statement I am taking the readings of voltage/current in a small induction generator; the readings are conveyed as negative on the voltage/current sensors on my data-logger, and positive on the multimeter in both areas. When the magnet passes through the coil, and power is generated...
Back
Top