The intensity of a wave is defined as I=P4πr2 I = P 4 π r 2. What is the formula for intensity of wave? Brightness involves how the human visual system perceives light, and it is not a physical quantity. Intensity is the power per unit area it is a physical quantity. Light is an electromagnetic wave: this was realized by Maxwell circa 1864, as soon as the equation c = 1/(e0m0)1/2 = 2.998 X 108m/s was discovered, since the speed of light had been accurately measured by then, and its agreement with c was not likely to be a coincidence. Light intensity represents the amplitude of light with the same wavelength, and light wavelength is a property of light that determines the colors of the light (Sliney, 2016). Visible light narrowly ranges from approximately 700 nm for red light to 400 nm for violet light in the broad spectrum. Is light intensity the same as wavelength? In the Young’s double – slit experiment, the intensity of light at a point on the screen where the path difference is λ is K,(λ being the wave length of light used). For each distance of the plant from the lamp, light intensity will be proportional to the inverse of, meaning distance squared. The light intensity is inversely proportional to the square of the distance – this is the inverse square law. How do you find the intensity of light at a distance? This answer tells you that the light intensity at your point on the sphere is equal to the number of watts that the bulb radiates divided by the surface area of the sphere. This final answer is given in watts per meters squared. How do you calculate the light intensity of a light bulb?ĭivide the bulb’s wattage by the answer from the previous step. The intensity varies with the distance from the source and the power of the source. The term intensity is used to describe the rate at which light spreads over a surface of a given area some distance from a source. 24 How is intensity measured? What is light intensity in physics?

Relative light intensity equation