One of the following answers is considered a luminous source

In the figure below, the ratio of the brightness of the light at Ahmed to the brightness of the light at Sultan equals

If the luminous flux of a light source is 1200 lumens, and it shines uniformly in all directions, what is the illuminance on a surface 2 meters away from the source?

If the distance between a light source and a flat surface is tripled, how does the illuminance on this surface change?

Which of the following factors does not affect the brightness of a luminous surface as seen by the human eye?

If the illuminance on a surface 3 meters away from a lamp is 50 lux, what is the illuminance on another surface 6 meters away from the same lamp?

A student stands \[2\;m\] from a light source with a flux of \[200\;Lm\]. The brightness of the light at this distance equals

A flame has a luminous flux of \[300\;Lm\]. At what distance should you stand so that the light reaches you with an illuminance of \[E= 95.5 LX \]

An observer stands \[3\;m\] from a light source. The brightness of the light at this distance was \[12\;LX\]. The light intensity equals

In the adjacent figure, the ratio of the brightness seen by observer [A] to the brightness of the light seen by observer [B] equals

In the figure below, if the brightness of the light seen by observer [A] is three times the brightness of the light seen by observer [B], then observer [A] is standing at a distance of

Huygens' principle states that

When white light passes through a prism, it decomposes into the seven colors of the spectrum. The reason for this is

The light that has the longest wavelength among this group of spectrum colors is

When two lights mix with each other and produce white light, we call these lights

When red and blue light are mixed, the resulting light is

Pigments are chemical substances that contain primary colors: magenta, cyan, and yellow.
When the primary colors are mixed in equal proportions, the resulting color is

When blue light is shone on a red apple inside a light-tight box with an opening, we see the apple inside the box as

What color results from mixing blue and yellow pigments?

What color results from mixing red, green, and blue light with equal intensity?

What is the complementary color of blue in the subtractive color system?

One of the following tools does not polarize light when it falls on it

If unpolarized light of intensity \[I₀\] passes through an ideal polarizer, what is the intensity of the resulting light?

Polarized light of intensity \[I₀\] passes through a second polarizer whose axis makes an angle of 60° with the axis of the first polarizer. What is the intensity of the resulting light?

Unpolarized light with an intensity of \[ 32\;W/m² \] passes through two consecutive polarizers; the axis of the second is perpendicular to the axis of the first. What is the intensity of the resulting light?

A star emits green light and is moving away from the Earth. Which one of the following lights cannot be seen by an observer standing on Earth?

A star emits light with a frequency of \[f=5×10^{14}hz\] and is moving towards the Earth's surface at a speed of \[v=3×10^7 m/s\]. The apparent frequency seen by an observer on Earth is equivalent to:

A star emits light with a wavelength of \[λ=5×10^{-7}m\] and is moving towards the Earth's surface.
An observer on Earth sees the star emitting light with a wavelength of \[λ_{obs}=4.5×10^{-7}m\]. The speed at which the star is moving is:

A star emits light with a frequency of \[f=5×10^{14}hz\] and is moving away from the Earth's surface at a speed of \[v=4.5 ×10^7 m/s\]. The apparent frequency seen by an observer on Earth is equivalent to: