Inverse square law

Front

What is the unit and symbol for illuminance?

Back

Lux - E

Front

What is the unit and symbol for luminous intensity?

Back

Candela - I

Front

What is the unit and symbol for luminous flux?

Back

Lumen - θ

Front

How do you calculate illuminance (E) at a point directly under a light source?

Back

E = I / d², where I is luminous intensity in candela and d is the distance from the light source.

Front

What is the illuminance directly below a lamp with luminous intensity of 500 candela suspended 2m above?

Back

125 lux

Front

True or False: The formula for calculating illuminance (E) is E = I / d².

Back

True

Front

What does the term 'luminous intensity' refer to?

Back

The amount of light emitted by a source in a particular direction, measured in candelas.

Front

What does 'luminous flux' measure?

Back

The total amount of light emitted by a source, measured in lumens.

Front

What is the relationship between distance and illuminance according to the inverse square law?

Back

Illuminance decreases with the square of the distance from the light source.

Front

If the distance from a light source is doubled, how does the illuminance change?

Back

The illuminance becomes one-fourth of its original value.