What is meaning of polar curve?

A polar curve is a shape constructed using the polar coordinate system. Polar curves are defined by points that are a variable distance from the origin (the pole) depending on the angle measured off the positive x-axis. For example, a cardioid microphone has a pickup-pattern in the shape of a cardioid.

How polar curve is useful to an illumination engineer?

The polar curves are used to determine the mean horizontal candle power (M.H.C.P.) These are also used to determine the actual illumination of a surface by employing the candle power in that particular direction as read from the vertical polar curve in illumination calculations.

Which polar curve is used for calculating mean horizontal candle power?

The mean horizontal candle power of a lamp can be determined from the horizontal polar curve by taking the mean value of the candle power in a horizontal direction. Mean spherical candle power can be determined from the vertical polar curve by Rousseau’s construction.

What are polar equations used for?

Polar coordinates are used often in navigation as the destination or direction of travel can be given as an angle and distance from the object being considered. For instance, aircraft use a slightly modified version of the polar coordinates for navigation.

What is efficacy of a lamp?

efficacy – The ratio of the light output of a lamp (lumens) to its active power (watts), expressed as lumens per watt.

What is candela used to measure?

The candela is used to measure the visual intensity of light sources, like light bulbs or the bulbs in torches. It is the only SI base unit based on human perception.

What do you mean by Rousseau’s construction?

[rü‚sō ′dī·ə‚gram] (optics) A geometric construction used to determine the total luminous flux of a lamp from a number of polar diagrams which give the effective luminous intensity of the lamp in various directions.

What is luminous intensity distribution?

The luminous intensity distribution curve is a graphic representation of the luminous intensity measurement of a luminaire. The distance of the contour of the luminous intensity distribution curve from the centre of the luminaire gives information about the luminous intensity in the respective direction.

What is CP in illumination?

Candlepower (abbreviated as cp or CP) is a unit of measurement for luminous intensity. It expresses levels of light intensity relative to the light emitted by a candle of specific size and constituents. In modern usage, candlepower is sometimes used as a synonym for candela.

What do you mean by MSCP and Mhcp?

M.S.C.P is the average value in all direction. Since 1 c.p emits 4p lumens MSCP lumens / 4π MHCP. Mean hemispherical candle power MHCP upper or lower: The average candle power of light source in all direction in a plane through the center of the source and perpendicular to its axis.

What is luminous flux measured in?

Luminous flux radiated by a light source is measured in lumens (lm). The lumen is the SI unit of luminous flux describing the quantity of light emitted by a source or received at a plane. The lumen is derived from the unit of luminous power, the candela (cd).

How are polar curves used in real life?

Besides mechanical systems, you can employ polar coordinates and extend it into a 3D ( spherical coordinates ). This will help a lot in doing calculations on fields . Example: electric fields and magnetic fields and temperature fields. In short, polar coordinates make calculation easier for physicists and engineers.

How do polar coordinates work?

In mathematics, the polar coordinate system is a two-dimensional coordinate system in which each point on a plane is determined by a distance from a reference point and an angle from a reference direction. The radial coordinate is often denoted by r or ρ , and the angular coordinate by ϕ , θ , or t .