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  2. Visual acuity - Wikipedia

    en.wikipedia.org/wiki/Visual_acuity

    For 6/6 = 1.0 acuity, the size of a letter on the Snellen chart or Landolt C chart is a visual angle of 5 arc minutes (1 arc min = 1/60 of a degree), which is a 43 point font at 20 feet. [10] By the design of a typical optotype (like a Snellen E or a Landolt C), the critical gap that needs to be resolved is 1/5 this value, i.e., 1 arc min.

  3. Orders of magnitude (power) - Wikipedia

    en.wikipedia.org/wiki/Orders_of_magnitude_(power)

    10 5: 1.67 × 10 5 W tech: power consumption of UNIVAC 1 computer 2.5–8 × 10 5 W tech: approximate range of power output of 'supercars' (300 to 1000 hp) 4.5 × 10 5 W tech: approximate maximum power output of a large 18-wheeler truck engine (600 hp) 10 6: mega-(MW) 1.3 × 10 6 W tech: power output of P-51 Mustang fighter aircraft 1.9 × 10 6 W

  4. Power factor - Wikipedia

    en.wikipedia.org/wiki/Power_factor

    Power flow calculated from AC voltage and current entering a load having a zero power factor (ϕ = 90°, cos(ϕ) = 0).The blue line shows the instantaneous power entering the load: all of the energy received during the first (or third) quarter cycle is returned to the grid during the second (or fourth) quarter cycle, resulting in an average power flow (light blue line) of zero.

  5. Order of magnitude - Wikipedia

    en.wikipedia.org/wiki/Order_of_magnitude

    Order of magnitude. Order of magnitude is a concept used to discuss the scale of numbers in relation to one another. Two numbers are "within an order of magnitude" of each other if their ratio is between 1/10 and 10. In other words, the two numbers are within about a factor of 10 of each other. [1]

  6. Total harmonic distortion - Wikipedia

    en.wikipedia.org/wiki/Total_harmonic_distortion

    Total harmonic distortion. The total harmonic distortion (THD or THDi) is a measurement of the harmonic distortion present in a signal and is defined as the ratio of the sum of the powers of all harmonic components to the power of the fundamental frequency. Distortion factor, a closely related term, is sometimes used as a synonym.

  7. One half - Wikipedia

    en.wikipedia.org/wiki/One_half

    One half is a rational number that lies midway between nil and unity (which are the elementary additive and multiplicative identities) as the quotient of the first two non-zero integers, . It has two different decimal representations in base ten, the familiar and the recurring , with a similar pair of expansions in any even base; while in odd ...

  8. Decibel - Wikipedia

    en.wikipedia.org/wiki/Decibel

    The decibel originates from methods used to quantify signal loss in telegraph and telephone circuits. Until the mid-1920s, the unit for loss was miles of standard cable (MSC). 1 MSC corresponded to the loss of power over one mile (approximately 1.6 km) of standard telephone cable at a frequency of 5000 radians per second (795.8 Hz), and matched closely the smallest attenuation detectable to a ...

  9. Magnification - Wikipedia

    en.wikipedia.org/wiki/Magnification

    Stepwise magnification by 6% per frame into a 39-megapixel image. In the final frame, at about 170x, an image of a bystander is seen reflected in the man's cornea. Magnification is the process of enlarging the apparent size, not physical size, of something. This enlargement is quantified by a size ratio called optical magnification.