• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

HYdrogen spectrum

Extracts from this document...


Physics Lab Report

Hydrogen spectrum

Name: Mena Nadum

Class: IB07


A hydrogen discharge tube is a device that can trap small amount hydrogen in a sealed tube of glass, and if potential difference is applied to that tube an emission of an atomic spectrum can be produced. The emission of the spectrum is produced from the excitation of the hydrogen electron (by the voltage) to a higher energy level and falling back to its original one.  In this practical a diffraction grating is used to analyze the emitted light into spectral Balmer (visible) lines. Using a spectrometer the wave length of each line can be determine and hence an experimental Rydbergs constant.


Hydrogen lamp

Diffraction grating


Voltage power supply


At the beginning of the experiment the slit of the collimator was adjusted to get a sharp focused light. The hydrogen lamp was placed in front of the slit. Then the diffraction grating was put at a right angle to the collimator. After the diffraction grating has analyzed the spectrum emitted, visible light was detected and spectral lines were produced at deferent angles.

...read more.


(max. value – min. value)/2 → [(2image00.png+0.2) -(2image00.png-0.2)]/2

The wavelength of each spectral line can be calculated using the diffraction grating equation:

image01.png= d sin ( image00.png)

Where d is the line spacing of the diffraction grating and in the experiment was

d= image02.png so its 1666.67nm

Since d value wasn’t measured in the experiment no uncertainties for it have been recorded. So  I found that it’s best to figure out an uncertainty to d by taking the last digit and get an uncertainty of ±0.01 nm.

Processed data1

Colors produced by the spectrum
















The uncertainties of the wavelengths were calculated by taking the relative uncertainty of each value and adding them together. Example:

The uncertainty of sin ( image00.png) for the color red = sin (22.9) = 0.389 is calculated as [sin(22.9+0.2) – sin(22.9-0.2)]/2 → image03.png± 0.004

Thus, the relative uncertainty of d + relative uncertainty of sin ( image00.png) = the relative uncertainty of the wavelength

image04.pngx 649=  5.37 image03.png ±6nm wavelength uncertainty

...read more.


The Balmer series:

        Red                        656.3 nm

        Blue                     486.1 nm

            Violet                         434.0 nm

        Violet                        410.2 nm

Estimating the uncertainty of R for each line was ignored since there would be an average R and its uncertainty can be calculated.

Average uncertainty of R was determined by taking (max. R value – min. R value)/2

Percentage average Uncertainty is then calculated:


Then the experimental R value was compared with the accepted value by calculating the percentage error:

Percentage error = [(experimental value – literature value)/ literature value] x100

Percentage error =image09.png

The error is fairly simple and the calculated percentage uncertainty was quite bigger than the percentage error. So this makes the experiment successful.

...read more.

This student written piece of work is one of many that can be found in our International Baccalaureate Physics section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related International Baccalaureate Physics essays

  1. Incandescent 100 watt light bulb ban: A bright Idea ?

    When you're shopping for light bulbs, people should look for those that produce more light with less energy, and light bulbs with high efficacy ratings mean more savings on power bills. People buy light bulbs with the highest efficacy rating to get the most light from the least amount of electricity and decrease your monthly power bills.

  2. Physics Wave revision question

    I B. II C. III D. IV (1) 18. Diagram 1 below shows the displacement of part of a medium through which a wave is travelling at time t = 0. Diagram 2 shows the displacement at a later time t = 4.0 s in which the wave has moved forward 10 cm.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work