Interest Guide, Meaning , Facts, Information and Description

In finance, interest is a surcharge on the repayment of debt (borrowed money). The fact that lenders demand interest for loans in capitalist countries can be explained by one or more of the following:

• time preference
• the time value of money
• the opportunity cost of money
• macroeconomic price changes (inflation)
• the risk of default on the loan (bankruptcy)

Mathematically, interest generally falls in one of the following two categories:

• simple interest, in which outstanding balances grow linearly with time. In each period, the total balance grows by some fraction of the principal (that is, of the original investment).
• compound interest, in which outstanding balances grow exponentially with time. In each period, the total balance grows by some fraction of the sum of the principal and the interest paid on all previous periods.

In either case, the fraction by which the balances grow is called the interest rate.

Economists sometimes refer to interest as rent on money. As with any rental, the market price (or rate) is subject to change to reflect market conditions. Interest rates are very closely watched market indicators, and have a dramatic effect on finance and economics.

Interest involves the future, which is uncertain. Some interest bearing investments are riskier than others. The greater the risk of the security, the more interest investors expect to receive.

Different parties will be offered different rates on debt obligations (such as loans). The measure of credit worthiness of an individual is called a credit rating or credit score. Other entities (such as governments and companies) will acquire a bond rating if they are active in bond markets.

Table of contents

1 Simple Interest 2 Compound Interest 3 Force of Interest 4 Continuous Compounding 5 History 6 See also 7 Finding related topics 8 External link

Simple Interest

Simple interest is seldom used in practice, mostly for estimating compound interest in short durations. In most cases, this is because the interest earned in previous periods is assumed to remain in the account. Only when the interest earned is immediately withdrawn from the account should simple interest be used. When interest is not collected as it is accrued (as with a certificate of deposit, where the payment is in a lump sum), the interest increases the amount of money subject to interest. In this case simple interest would not reflect the opportunity cost that the lender experiences.

The accumulation function for simple interest is a linear function in terms of time. It is defined as the following:

Compound Interest

With compound interest, the frequency of compounding influences the total amount of interest paid over the life of the loan. The accumulation function for compound interest is an exponential function in terms of time.

Force of Interest

In mathematics, the accumulation function are often expressed in terms of e, the base of the natural logarithm. This facilitates the use of calculus methods in manipulation of interest formulas. This is called the force of interest.

The force of interest is defined as the following:

When the above formula is written in differential equation format, the Force of Interest is simply the coefficient of amount of change.

The force of interest for compound interest is a constant for a given , and the accumulation function of compounding interest in terms of force of interest is a simple power of e:

Continuous Compounding

For interest compounded a certain number of times per year, such as monthly or quarterly, the formula is:

where B is the balance, P is the beginning balance, r is the annual interest rate, n is the number of times per year the interest is compounded, and t is the number of years of the loan.

Continuous compounding can be thought as making the compounding period infinitely small.

The formula used to calculate the balance B for continuously compounded interest, is the beginning balance P times the aforementioned e raised to the power of the product of the annual interest rate r, and the number of years of the loan t. This formula is usually written:

History

The collection of interest was forbidden by Christian and other religions under laws of usury. This is still the case with Islam which results in a special type of Islamic banking. Gesell researched the destabilizing effect of interest (an asset will increase beyond any limit over time) in his Freiwirtschaft theory, which includes negative interest rates.

Depending on the source, Albert Einstein referred to compound interest as the eighth's wonder of the world, the human race's greatest invention, or the most powerful force of the universe.

See also

• finance
• mortgage
• interest rate
• risk free interest rate
• Term Structure of Interest Rates
• Fisher equation
• credit rating agency
• usury

Finding related topics

• list of finance topics
• list of accounting topics
• list of management topics
• list of human resource management topics
• list of marketing topics
• list of economics topics
• list of information technology management topics
• list of production topics
• list of business law topics
• list of business ethics, political economy, and philosophy of business topics
• list of business theorists
• list of economists
• list of corporate leaders
• list of companies

External link

• Compound Interest Calculation

This is an Article on Interest. Page Contains Information, Facts Details or Explanation Guide About Interest

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