# About James Joule

James Prescott Joule |

**James Prescott Joule**(1818–1889), Scotland.

James Prescott Joule was one of five children in the

family of a well-to-do brewery owner. Since he was a

sickly child with a spinal deformity, both he and his

brother were educated at home until the age of 15 and

later by private tutors.

The famous English chemist,

**John Dalton**, taught

them chemistry, physics, and the methods of

**.**

scientific experimentation

scientific experimentation

Later in life Joule acknowledged that John Dalton encouraged him to increase his knowledge of science and of original research.

When James’ father died, he and his brother ran the

brewery, which prevented him from attending a

university. However, this did not deter him from setting

up a laboratory in his home and continuing his interest

in science after his day at the brewery.

He became proficient in mathematics and learned how

to make accurate measurements in the

brewery.

His home experiments resulted in his ability

The unit of work and energy was named after him (the

that states that

the rate of the heat given off as watts in joule units,

is the resistance in the conductor in ohms and

the amount of the current (amps) squared.

industries using electricity as a source of energy. The

resistance to an electric current flowing through a

conductor is analogous to the friction of air, the

movement of engine parts, and tires on the road

for a moving car. The electrical, as well as

mechanical, energy is not just ‘‘lost,’’ rather it is

converted to heat, just as is friction.

Joule was interested in improving the mechanical

advantage of electric motors, but because they were

very primitive during his lifetime, he devoted more of

his work to improving the efficiency of steam engines.

He accurately predicted that electric motors eventually

would replace most other types of mechanical devices.

the brass barrels of cannons,

he noticed that large amounts of heat were generated.

It became obvious that friction

generated by the work of turning the bit in the metal

resulted in heat. Julius von Mayer

also was interested in this relationship and developed

a figure for the mechanical equivalent of heat that was

not very accurate.

James Prescott Joule was the first to consider heat

as a form of energy in his calculation.

He conducted exacting experiments to determine the

amount of heat generated not just by electricity but

also by mechanical work. Joule calculated the amount

of mechanical work needed to produce an equivalent

amount of heat.

He demonstrated that

the

Since 10 million ergs are equal to 1 joule, named

after James Joule, 4.18 joules are then equal to 1

calorie of heat.

Joule’s work enabled others to perfect

the

that

His home experiments resulted in his ability

**to**

measure slight increases in temperature under

various conditions, which led to hismeasure slight increases in temperature under

various conditions

**theory for the**

equivalence of work and heat energy.equivalence of work and heat energy

The unit of work and energy was named after him (the

*Joule*, or the symbol ‘‘J’’)**Now, with his law****Joule’S law**

Joule’s law states that:

Joule’s law states that:

*The relationship for heat produced by an electric current in a conductor is related to the resistance of the conductor times the square of the amount of current applied*:**By experimentation, James Joule established the law**

H = R I²

H = R I²

that states that

**when a current****of voltaic**

electricity is sent through a metal or other type

of conductor, the heat given off over a specific

time period is proportional to the resistance of

the conductor multielectricity is sent through a metal or other type

of conductor, the heat given off over a specific

time period is proportional to the resistance of

the conductor multi

**plied by****the square of the**

electric current.electric current.

**The equation for this law is**:__H = R I²__, where*H*isthe rate of the heat given off as watts in joule units,

*R*is the resistance in the conductor in ohms and

*I²*isthe amount of the current (amps) squared.

**The application of Joule's law**

**The application of this law is important in all**

industries using electricity as a source of energy. The

resistance to an electric current flowing through a

conductor is analogous to the friction of air, the

movement of engine parts, and tires on the road

for a moving car. The electrical, as well as

mechanical, energy is not just ‘‘lost,’’ rather it is

converted to heat, just as is friction.

Joule was interested in improving the mechanical

advantage of electric motors, but because they were

very primitive during his lifetime, he devoted more of

his work to improving the efficiency of steam engines.

He accurately predicted that electric motors eventually

would replace most other types of mechanical devices.

**Another law**

**:**

**Law for the mechanical equivalent of heat**

**:***A fixed amount of mechanical work (expenditure of energy) ends up in a fixed quantity of heat.***Earlier in 1798 when Count Rumford was boring out**

An interesing story

An interesing story

the brass barrels of cannons,

he noticed that large amounts of heat were generated.

It became obvious that friction

generated by the work of turning the bit in the metal

resulted in heat. Julius von Mayer

also was interested in this relationship and developed

a figure for the mechanical equivalent of heat that was

not very accurate.

James Prescott Joule was the first to consider heat

as a form of energy in his calculation.

He conducted exacting experiments to determine the

amount of heat generated not just by electricity but

also by mechanical work. Joule calculated the amount

of mechanical work needed to produce an equivalent

amount of heat.

He demonstrated that

**41 million ergs of work**

produced 1 calorie of heat, which is now known asproduced 1 calorie of heat

the

*mechanical equivalent of heat*.Since 10 million ergs are equal to 1 joule, named

after James Joule, 4.18 joules are then equal to 1

calorie of heat.

Joule’s work enabled others to perfect

the

**law for the conservation of energy**, which statesthat

*energy, like mass, cannot be created or destroyed*

but can be changed from one form to another.

I hope that this post was useful.but can be changed from one form to another.

I hope that this post was useful.