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Snellen chart. Purpose. Snellen chart is used to estimate visual acuity (last three rows are 20/15, 20/13 and 20/10) A Snellen chart is an eye chart that can be used to measure visual acuity. Snellen charts are named after the Dutch ophthalmologist Herman Snellen who developed the chart in 1862 as a measurement tool for the acuity formula ...
An example of the Landolt C eye chart (also known as the Japanese eye chart.). Numerous types of eye charts exist and are used in various situations. For example, the Snellen chart is designed for use at 6 meters or 20 feet, and is thus appropriate for testing distance vision, while the ETDRS chart is designed for use at 4 meters.
Shewhart individuals control chart. In statistical quality control, the individual/moving-range chart is a type of control chart used to monitor variables data from a business or industrial process for which it is impractical to use rational subgroups. [1] The chart is necessary in the following situations: [2] : 231.
The elementary charge e, i.e. the negative charge on a single electron or the positive charge on a single proton: 10 −18: atto-(aC) ~ 1.8755 × 10 −18 C: Planck charge: 10 −17: 1.473 × 10 −17 C (92 e) – Positive charge on a uranium nucleus (derived: 92 x 1.602 × 10 −19 C) 10 −16: 1.344 × 10 −16 C: Charge on a dust particle in ...
Negative refraction. Negative refraction is the electromagnetic phenomenon where light rays become refracted at an interface that is opposite to their more commonly observed positive refractive properties. Negative refraction can be obtained by using a metamaterial which has been designed to achieve a negative value for (electric) permittivity ...
Shaped charge. 1: Ballistic cap; 2: Air-filled cavity; 3: Conical liner; 4: Detonator; 5: Explosive; 6: Piezo-electric trigger. A shaped charge is an explosive charge shaped to focus the effect of the explosive's energy. Different types of shaped charges are used for various purposes such as cutting and forming metal, initiating nuclear weapons ...
Line chart. A line chart or line graph, also known as curve chart, [1] is a type of chart that displays information as a series of data points called 'markers' connected by straight line segments. [2] It is a basic type of chart common in many fields. It is similar to a scatter plot except that the measurement points are ordered (typically by ...
A surface charge is an electric charge present on a two-dimensional surface. These electric charges are constrained on this 2-D surface, and surface charge density, measured in coulombs per square meter (C•m −2 ), is used to describe the charge distribution on the surface. The electric potential is continuous across a surface charge and the ...