# How to find lambda

Letter λ (lambda) denotes the wavelength of a radiation. This quantity can be measured, can be calculated theoretically, but if the radiation is visible even by eye to determine.

## Instruction how to find lambda

Step 1:

To calculate the wavelength of the radiation, knowing the frequency and velocity of propagation of the radiation, divide the second value to the first. If instead the frequency of known period, multiply it by the speed of propagation of the radiation. Finally, if we know the angular frequency of the radiation, multiply the speed by 2p, and then divide the result on the cyclic frequency. To the result was in the SI system, the pre-move it all the same magnitude of the task conditions. Then put the result back in a comfortable unit for you.

Step 2:

If the radiation is light, its wavelength in a vacuum, determine on the eye: red - from 635 to 690 nm, orange - 590, yellow - from 570 to 580, green - from 510 to 520, blue - from 440 to 480, purple - from 380 to 400.

Step 3:

With a special instrument - a spectrometer to determine the wavelength of light can be more accurate than the eye. If it is polychromatic, to determine its spectral composition is possible only with the help of this device for this aim the light beam at the input of the device window. It will pass through the slot perpendicular to the prism and then through the lens itself, and then falls on a scale, or a line sensor. In the second case, the measurement result will make the processing electronic unit.

Step 4:

To find the wavelength decimeter or centimeter range to connect the antenna to the wavemeter, then start to change its size gradually. When he will be equal to half the wavelength of the wave meter readings will be maximized.

Step 5:

Point the thin light beam exactly perpendicular to the grating. number of spots will appear on the screen. Measure the angle between the imaginary line that continues to move the beam after the grating line connecting the entry point of the beam in the first grid of spots. Find the sine of the angle, and then multiply by the distance between two adjacent grid lines. We obtain the wavelength, which is expressed in the same units as the distance between the lines.