Physics Lab Equipment

LEOK-70 Balmer Series of Hydrogen & Rydberg Constant

LEOK-70 Balmer Series of Hydrogen & Rydberg Constant


  • Stable aluminum rail for easy alignment

  • Hydrogen-Deuterium lamp

  • Detailed instructional manual


The Balmer series is referred to as a set of discrete emission spectral lines of the Hydrogen atom. The visible Balmer series involves the electron transitions from the higher energy levels (≥ 3) to the second energy level (n = 2) where n is the principal quantum number of the electron.


The wavelengths of the Balmer series of the Hydrogen atom can be calculated from equation 1/λ = R (1/22-1/n2), n=3, 4, 5, ..., where R is an empirical constant called the Rydberg constant (R=1.096776x107 m-1).


This apparatus uses a diffraction grating to disperse the collimated beam of a Hydrogen-Deuterium lamp and a digital protractor stage along with a telescope to measure the diffraction angles of the Balmer series lines. Once the wavelengths are determined, the experimental value of the Rydberg constant can be derived.

The instruction manual contains comprehensive materials including experimental configurations, principles and step-by-step instructions. Please click to view some sample pages of the instruction manual.


Hydrogen-Deuterium LampWavelengths: 410, 434, 486, 656 nm
Digital ProtractorResolution: 0.1°
Condensing Lensf = 50 mm
Collimating Lensf = 100 mm
Transmissive Grating600 lines/mm
TelescopeMagnification: 8 x; diameter of objective lens: 21 mm with internal reference line
Optical RailLength: 74 cm; aluminum

Part List

Optical rail1
X-translation carrier1
Optical rotation stage with digital protractor1
Lens holder2
Adjustable slit1
Telescope holder (tilt adjustable)1
Hydrogen-Deuterium lamp with power supply1 set

LEOK-70 Balmer Series-1.jpg

Spectral lines of Hydrogen atom


LEOK-70 Balmer Series-2.jpg

Schematic of spectral dispersion

Copyright © Lambda Scientific Systems, Inc. 2010-2023. All rights reserved.