A sinusoidal magnitude is characterized  by an equation of the type :

V(t)=A sin(2πft+φ)

• A: Amplitude of the signal. V(t) will have the same units as A.
• 2πft+φ: the argument or phase of the function expressed in radians
• f: frequency of the signal expressed in Hertz. One sometimes manipulates the pulsation, ω=2πf, the units of which are rad.s^-1.
• Φ is the phase at the origin (time zero) expressed in radians

The Fresnel Representation, with vectors that are also called "phasors", is a means of representing a sinusoidal function  by just taking the amplitude and the phase of origin into account. This representation is very useful in optics or in electronics, for summing, taking the derivatives of and integrating sinusoidal functions of the same frequency, but of different amplitudes and phases.

The four stroke engine is an internal or heat combustion engine commonly used to power transport vehicles. The complete cycle requires four successive phases. During the intake stroke, a fuel-air mixture is drawn into the cylinder. It is then compressed by the upward movement of a piston. The mixture is ignited by a spark plug to initiate the combustion stroke, the source of power, and finally the spent gases are forced out during the exhaust stroke. The cycle repeats itself over and over again.

The incenter of a triangle is the point of intersection of the triangle's three angle bisectors.

Animation brought to you in cooperation with the Musée des Arts et Métiers - Paris.

The velocipede (literally "fast foot") uses a chain set with a fixed sprocket on the front wheel: one turn of the pedals is the equivalent of one turn of the driving wheel.

To travel greater distances with each turn of the pedals it is necessary to increase the diameter of the front wheel: the Penny Farthing is an extreme application of this principle.

The bicycle uses a transmission system that involves a chain connecting two sprockets of different sizes, which provides greater distance to be covered with each turn of the pedals.

A magnet creates a disturbance in the space surrounding it called the magnetic field. For a long time, magnets were the only known source of this magnetic field.

The existence of the field can be revealed by a force that acts on certain materials and on charges in motion.

A simple experiment to perform would be to sprinkle  iron filings in the neighborhood of the magnet. Each grain of metal becomes magnetized and, via mutual attraction, aligns itself along particular lines. These lines of force are also called field lines. They map out the magnetic distrurbance created by the sources present.

An electrical circuit consists of :

• At least two components (also called dipoles because they have two poles) one of which is the generator (also referred to as the source).
• Conducting wires that connect the components to form a closed loop that enables current to flow.

Numerous forms of transpoort operate using electrical energy. Regardless of the dipole used, an electric motor is connected to the generator (not shown in the photos) by two conducting wires.

The electric power available at the terminals of a dipole is equal to the product of the current (I, in amperes, or "amps") and the voltage (E, for "electromotive force", in volts).

Remark: The colors chosen are not the conventional ones. The voltage and the current  could be direct or alternating.

Animation brought to you in cooperation with the Musée des Arts et Métiers - Paris.

The velocipede (literally "fast foot") uses a chain set with a fixed sprocket on the front wheel: one turn of the pedals is the equivalent of one turn of the driving wheel.

To travel greater distances with each turn of the pedals it is necessary to increase the diameter of the front wheel: the Penny Farthing is an extreme application of this principle.

The bicycle uses a transmission system that involves a chain connecting two sprockets of different sizes, which provides greater distance to be covered with each turn of the pedals.

Brought to you in cooperation with the Musée des Arts et Metiers - Paris.

A gear system is one involved in the transmission of motion. The two toothed wheels  assure a driving force without slippage.  In these four systems,  the driving wheel (at top) turns at a constant speed.

• First case: the "Maltese Cross " system transforms the contiunuous rotation into discontinuous motion: this is a turn counter.
• Other cases: the variable speed of the lower wheel is determined by the wheel's geometry.

Animation produced in collaboration with the Musée des Arts et Metiers - Paris.

The arithmetic machine created by Blaise Pascale (1623-1662) - the Pascaline - was one of the first mechanical calculating devices (first model 1642). It's a calculating machine because the carrying over across places occurs automatically.

It enables one to directly add and subtract.  It is also possible to multiply and divide using successive additions and subtractions.

Animation brought to you in cooperation with the Musée des Arts et Métiers - Paris.

The velocipede (literally "fast foot") uses a chain set with a fixed sprocket on the front wheel: one turn of the pedals is the equivalent of one turn of the driving wheel.

To travel greater distances with each turn of the pedals it is necessary to increase the diameter of the front wheel: the Penny Farthing is an extreme application of this principle.

The bicycle uses a transmission system that involves a chain connecting two sprockets of different sizes, which provides greater distance to be covered with each turn of the pedals.