The pascal (symbol: Pa) is the SI derived unit of pressure used to quantify internal pressure, stress, Young’s modulus, and ultimate tensile strength. The unit, named after Blaise Pascal, is defined as one newton per square metre and is equivalent to 10 barye (Ba) in the CGS system.

Pascal’s calculator

Blaise Pascal

1,013.25 mbar

Watt

Units. The dimension of power is energy divided by time. In the International System of Units (SI), the unit of power is the watt (W), which is equal to one joule per second. Other common and traditional measures are horsepower (hp), comparing to the power of a horse; one mechanical horsepower equals about 745.7 watts.

Newton-metre

dioptre

Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that quantifies how strongly it resists electric current. Resistivity is commonly represented by the Greek letter ρ (rho). The SI unit of electrical resistivity is the ohm-meter (Ω⋅m).

The measured transit time is converted to a distance using the formula d=t/v Where d is the distance, t is the time and v is the velocity. Two types of A-scan ultrasound biometry are currently in use. The first is contact applanation biometry. This technique requires placing an ultrasound probe on the central cornea.

In the former, the cylinder power is a number of diopters more convergent than the sphere power. That means the spherical power describes the most divergent meridian and the cylindrical component describes the most convergent.

A toric lens is a contact lens that’s shaped in a particular way. The shape of toric contact lenses creates different refractive, or focusing, powers on the vertical and horizontal orientations.

A lens that is plane (plano) in one meridian and has its full convex or concave curvature in the meridian at right angles. Cylindrical lenses are used to correct ASTIGMATISM.

A cylindrical lens is a lens which focuses light into a line instead of a point, as a spherical lens would. The curved face or faces of a cylindrical lens are sections of a cylinder, and focus the image passing through it into a line parallel to the intersection of the surface of the lens and a plane tangent to it.

Système international

The ohm (symbol: Ω) is the SI derived unit of electrical resistance, named after German physicist Georg Ohm.

Four-terminal sensing (4T sensing), 4-wire sensing, or 4-point probes method is an electrical impedance measuring technique that uses separate pairs of current-carrying and voltage-sensing electrodes to make more accurate measurements than the simpler and more usual two-terminal (2T) sensing.