What is Interest: Definition and 296 Discussions

Interest, in finance and economics, is payment from a borrower or deposit-taking financial institution to a lender or depositor of an amount above repayment of the principal sum (that is, the amount borrowed), at a particular rate. It is distinct from a fee which the borrower may pay the lender or some third party. It is also distinct from dividend which is paid by a company to its shareholders (owners) from its profit or reserve, but not at a particular rate decided beforehand, rather on a pro rata basis as a share in the reward gained by risk taking entrepreneurs when the revenue earned exceeds the total costs.For example, a customer would usually pay interest to borrow from a bank, so they pay the bank an amount which is more than the amount they borrowed; or a customer may earn interest on their savings, and so they may withdraw more than they originally deposited. In the case of savings, the customer is the lender, and the bank plays the role of the borrower.
Interest differs from profit, in that interest is received by a lender, whereas profit is received by the owner of an asset, investment or enterprise. (Interest may be part or the whole of the profit on an investment, but the two concepts are distinct from each other from an accounting perspective.)
The rate of interest is equal to the interest amount paid or received over a particular period divided by the principal sum borrowed or lent (usually expressed as a percentage).
Compound interest means that interest is earned on prior interest in addition to the principal. Due to compounding, the total amount of debt grows exponentially, and its mathematical study led to the discovery of the number e. In practice, interest is most often calculated on a daily, monthly, or yearly basis, and its impact is influenced greatly by its compounding rate.

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  1. B

    Pick adviser based on matching research interest vs. adviser competence

    Hi all, I intend to go into some form of condensed matter theory physics after I finish my 1st year of PhD studies (I'll finish that this coming May). I have met some CMT profs who are proficient at what they do, are intent on researching, etc., and some profs who seem to be either a) rather...
  2. James889

    Calculating Interest with Recursive Function

    Hi, I am trying to write a simple recursive function for calculating money in the bank after a certain amount of years. However i run into trouble since i need the new_base variable to be static(i need it to "remember" the base from the previous run) But trying to compile the program i...
  3. B

    How to calculate the interest forumula

    Homework Statement If you deposit $deposit into a bank account each year and get y% annual interest, the simple formula is \frac{deposit((1+y)^{years}-1)}{y} How is this formula calculated? What's going on? Let's look at $50, 6% interest, two years. Maybe I'm supposed to be dropping $50 in...
  4. T

    Engineering Linking physics interest with civil engineer [2 out of 1]

    Dear friends, I am completing my bachelors in engineering in civil engineering this year. I always had a inclination towards physics from childhood but followed the most usual path of engineering due to family. Now, my plan is to go into a field which is similar to physics or requires...
  5. H

    Mental processes and interest in mathematics

    I could chalk up what I'm about to describe to you as me simply being an "evening person", but I'm interested in whether the following is a well known phenomenon, very common, and or simply trivial and unimportant. A bit of background info: I am between the ages of 15 and 20. I love math. I...
  6. K

    Perceptions of Disparate Fields of Interest

    I often straddle two very separate worlds. First, let me explain. I am both a musician and a mathematician. I'm a fairly accomplished pianist (went to Interlochen, have won a few competitions, getting all my education paid for because of piano), and I say this NOT to brag, but to give some...
  7. H

    Loosing interest (last year of undergrad)

    Hi, I was hoping for just about any advice in my situation, to gain some perspective. I'm now on my last year of bachelors degree in physics and I feel that I'm loosing interest in studying physics anymore. This begin when I started therapy for an anxiety disorder. The therapy has been...
  8. E

    What resources are available for self-teaching pre-calculus mathematics?

    Hi, First of all, sorry if this kind of thread has been posted before. If so, then a reference to that thread would be appreciated :) So here we go. I always found maths to be boring in school, I did ok, but I didn't like it. But lately I've started to become fascinated by it. String- or...
  9. S

    Solving a Financial Problem: Calculating Withdrawals, Interest & Remaining Funds

    Homework Statement initial amount = $450 000 interest rate = 4.8% per month withdrawal = $3600 per month This is a question on an old test paper. It is calculator assumed. We use Casio classpad calculators. a) amount remaining after ten years? $173462.47 b)time to exhaust account? 14.5 years...
  10. nomadreid

    Radioactive decay versus compound interest

    The fact that radioactive decay and continuous compound interest end up with the same formula (with the "rate" being negative in the former and positive in the latter) seems to me to be more a result of the ubiquity of the exponential function in solving differential equations than any common...
  11. marcus

    What is SO(14) or SO*(14) Unification? Appeal to 't Hooft?

    Rhody raised this question. Garrett tweeted that he had talked with 't Hooft about unification and that 't Hooft likes SO(14). http://twitter.com/#!/garrettlisi/status/111135200192376832 So what's up with that? I was interested enough to look around and did not find much (tell me what I missed...
  12. V

    Interest continuously compounding with a variable prinicple

    Homework Statement This is a question I *might* have already got the answer to, I'd just like for someone very good with calculus and algebra to verify/answer the question themselves. To be more exact with the problem, we are putting 1 dollar (a variable principle) into a continuously...
  13. V

    When does return on interest, equal your annual principle savings

    This is a question I *might* have already got the answer to, I'd just like for someone very good with calculus and algebra to verify/answer the question themselves. To be more exact with the problem, we are putting 1 dollar (a variable principle) into a continuously compounded interest account...
  14. T

    Compound Interest With Repayments problem

    1. A 30 year old employee on a starting salary of $20 000 per year pays 5% of this into a superannuation scheme to which the employer also contributes 5% of the employee’s salary. If the fund is compounding at 5% p.a., find the lump sum payout when the employee retires at 60. Note: This...
  15. S

    Schools Finding Math Graduate School by Interest

    Graduate school applications are steadily approaching, and I am begging to investigate different institutions to apply to for math. Right now, I am performing a coarse inspection of schools, based on a few criterion. One of the more important of which is how strong they are in different...
  16. R

    Mech. Design Eng. - solid interest. IT/Databases - a new one. How to combine?

    I am very much interested in design engineering, development of consumer, scientific and medical devices. My favourite aspects of engineering include mathematics, CAD and computational engineering. I would say that my key strengths lie in analytical, mathematical thinking and very strong...
  17. E

    How to increase interest in ASME

    I'm hoping this is a good place to start with this question. I'm the incoming president of my university's ASME branch and I want to find unique ways to increase interest. Maybe I'm being to idealistic, but I feel like the organization has seen quite a drop off in interest in the last few years...
  18. H

    Meaning of derivative in terms of interest rate?

    Homework Statement The total cost of repaying a student loan at an interest rate of r% per year is C=f(r). a. What is the meaning of the derivative f '(r)? b. What does the statement f '(10)=1200 mean? Homework Equations The Attempt at a Solution For part a I think the...
  19. C

    Interest: Basic knowledge at medicine making

    It would be awesome if there was a course - intro to medicine making where I would get to create a pill but there isn't. What would be the closest thing to it? I thought I could major in 1 field to get the medicine knowledge but even that's not true. Even inside pharmacology, there are more...
  20. Femme_physics

    Bank interest plans. I tried to use the formula this time.

    Homework Statement In a certain bank they offer 2 saving plans Plan A gives yearly interest of 5%, and you can invest in this plan only in units of full year. Plan B gives a biyearly interest of 10% and you can invest in this porgram in units of 2 full years. A man has decided to invest...
  21. Femme_physics

    Algebra, percentages bank interest problem (simple)

    Well, it seems simple, anyway, but I'm not sure why my methodology would be wrong. Homework Statement In a certain bank they offer 2 saving accounts. Plan A gives an annual interest of 6% Plan B gives an interest of 12% once every 2 year. What's the preferable plan if you want to...
  22. Q

    Electrodynamics Causing me to loose interest in physics

    I'm in my final year of undergrad and this semester I'm doing electrodynamics. Well I'm finding the subject to be very dry, difficult Maths and trying to study the content is just boring. Next year I want to go into masters, but I need to decide whether I want to do it in Maths or physics. At...
  23. Q

    An interest thought experiment

    Suppose we have a detector which can detect the electromagnetic wave. If there exists the electromagnetic wave, the detector will flash. Now, A holds this detector and runs at a constant velocity relative to a charged particle. Will the detector flash? I think it will. In Chapter 11.10 of...
  24. marcus

    Causes of loss of interest in String program

    Tom's thread "Why I'm REALLY disappointed..." continues to get increasingly thought-provoking and informative. I summarized some recent discussion here: https://www.physicsforums.com/showthread.php?p=3219363#post3219363 I had some reaction to recent posts by Suprised and Tom that I will put in...
  25. O

    Topics of Present Day Interest in General Relativity

    Hi there I'm currently in a senior year intro GR course (at the level of Carroll and Ryder), and we're to write a research paper about a topic of "present day interest in General Relativity", about 15 pages in length. I'm having trouble figuring out a topic that would be appropriate under...
  26. B

    Getting rejected w/ solid academic record but mismatch of research interest

    Hi all, something strange has happened. I've had to speak with the universities I've applied to because a certain university demanded I respond to their offer of admission by March 09, and appeared to be reluctant to extend the deadline to March 18. (I later found out this was rather...
  27. marcus

    What caused the shift of interest in quantum cosmology?

    This raises an interesting physics question. What physics reason could there be for the shift of researcher interest in quantum cosmology which this Inspire search illustrates? Here is the Inspire top ten quantum cosmo list for 1996-1998...
  28. N

    How are interest payments on IMF loans apportioned among member countries?

    Hello! Not sure of this is the right place for this question, but here it is anyway: It concerns the International Monetary Fund, I was wondering how the interest on IMF loans are apportioned. I suppose a consideration of how loans are provided is necessary. For example, I do not know if all...
  29. C

    How important is interest in learning physics?

    If i find interest in it, would it make it easier to understand? If so, what are some ways of forming interest? I usually just study so as to pass a test.Which hasnt worked well for me. I just do enough to so that i can solve problems that will be similar to tests
  30. B

    Low interest rates: the original fiscal stimulus

    Now that it seems like the popularity of conservatism is growing with resistance to fiscal stimulus spending associated with the democratic party, the question becomes what will happen with interest rates. It seems like rising interest rates used to be associated with democrats in the white...
  31. 1

    Music What Should I Listen to After Mozart's Symphony #40?

    After taking an intersession music appreciation course, I have a new interest in music from the classical era. Mozart's Symphony #40 in G minor is the best sound I've ever heard - period. Anyone have any recommendations for other things I should check out? I hear it's great to have in the...
  32. rcgldr

    Econonmic policies to balance interest of the many versus interests of the few?

    There are two main issues I'm interested in for this thread, and how far should regulations have to go to control these issues? 1. The conflict where an individual is in a position to make decisions that benefit the individual at the risk or detriment of the company or other employees...
  33. R

    Help with physics REU statement of interest

    Help with physics REU statement of interest! I've been working on this for several days and it just comes off as so blah and uninspired to me. I'm a bad writer and I haven't written an essay in 7 months so I'm having trouble wording things the way I'd like. Please critique what I have so far...
  34. A

    Compound Interest Formula and Natural Logarithms

    Homework Statement Solve the compound interest formula for t by using natural logarithms. Homework Equations A=P(1+\frac{r}{n})^{nt} The Attempt at a Solution I start by dividing both sides by P. I then take the natural log of both sides and end up with ln(\frac{A}{P})=nt *...
  35. sparkey

    Electrician with an interest in most of the sciences

    i didnt see a newbe topic so i'll put this here. new guy here (as if it wasnt obvious). I am a 25yo electrician with an interest in most of the sciences. i have a particular interest in particle physics and quantum mechanics as well as anything related to astronomy. I am probably going to be...
  36. T

    DE - Continuously Compounded Interest

    Homework Statement A new savings account with an initial balance of zero is made. You save money continuously, at a rate of $500 per month. Also, every month you plan to increase this rate by $5. you've found a bank account that pays continously compounded interest at a rate of 8% per year...
  37. L

    Continuous compound interest with additional transactions

    1. The accountants at HR office of the Sirius Cybernetics Corporation have determined that the company would need additional $10 billion in its pension fund account over and above the current projected amount at the end of year 2030. (a) Assuming the fund's balance will be growing, compounds...
  38. A

    Programs Please help Liberal arts degree w/ an interest in physics

    PLEASE HELP! Liberal arts degree w/ an interest in physics I would like to get some feedback to gauge my interest level in physics. At the present I feel passionate about physics but as they say one can never think clearly when they're in the eye of the storm. A little background: I just...
  39. O

    B.F.A. Pursuing Physics: Paths & Advice

    I think I am a bit of an odd case, but I might not be. I have a B.F.A., no joke. When I was young I recognized that other people recognized that I was skilled in drawing. I think that gave me a bit of tunnel vision. Even though I pursued other interests, I always thought of myself as an artist...
  40. L

    Where Can I Find Low/No Interest Student Loans?

    I've never had a student loan before, but I just looked at one and the interest was ridiculous. You end up paying more than twice the amount you received. Is there, by any chance, a place that offers student loans at no interest, or very low interest? Thanks.
  41. C

    Weight on a fulcrum style problem - Personal Interest

    Just to preface, this isn't something that I've been given as homework, I'm not currently enrolled in any schooling, however as a matter of personal interest I wanted to work out the solution to the problem without a guess-check-improve method. I have an idea, and it seems too obvious to be true...
  42. J

    News Do Low Interest Rates Really Help The Economy?

    The theory goes that lowering interest rates allows people to borrow more and this stimulates consumption. However, as I mentioned in https://www.physicsforums.com/showthread.php?t=415842" low interest rates allow people to hold onto non perishable goods longer. The consequences is a surplus of...
  43. D

    Sports / Community Service / Interest Groups

    I would like to know how much weightage is taken into account for activities outside class, when applying for a university scholarship... Are sports activities given preference over, for example, science interest groups such as astronomy? What advantage does multiple club memberships hold? Is...
  44. J

    How Long to Double Your Money with Compound Interest?

    A fixed deposit investment attracts interest of 4.3% p.a. compounded annually. How long will $30 000 take to double in value?
  45. S

    Conflict of interest: the bad is always there?

    Hey all, So I'm relatively new to the professional life. The question of "conflict of interest" is bothering me a lot lately as I'm not sure about how the words are defined, and which kind of interest is looked down upon. For example, I was thinking about this case, which I observe in many...
  46. Simfish

    High Demand, Low Interest Physics Fields: Astrophysics & Astrobiology

    Which fields of physics have relatively high demand and relatively low student interest? (especially among strong students?) I'm especially interested about astrophysics. Does computational astrophysics have high demand among strong students? What about astrobiology? The reason I'm asking...
  47. J

    Looking for interest in Carrol & Ostlie study group

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  48. E

    Developed an interest in, Astronomy? Astrophysics?

    I've recently been reading articles (primarily wikipedia) about different plants, their sizes, and all elements required in the identification of certain stars, constellations etc. I'd like to learn more but simply visiting pages on Wikipedia endlessly for hours won't accumulate much aside from...
  49. N

    Notice an interest correlation between hydrogen, helium, dark matter and dark energy

    matter in The universe is thought to be made up of 75 percent hydrogen and helium is thought to make up 25 percent of helium; Dark matter is thought to make up 25 percent of the universe and 75 percent dark energy; that's an interesting coincidence. , and currently physicists are not certain...
  50. L

    Schools Options to pursue interest in physics (high school student)

    I'm a high school student from the Netherlands. I'm currently 17 and in my final year of high school. Recently I've become very interested in physics. It really is a new interest among many of my other interests (classical music, literature, even debating and politics), but I would like to learn...
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