What is the difference between band spectrum and line spectrum in em spectrum

Question

dear friends,

please let me know the difference between band spectum, line and continuous spectrum? i can easily understand if u could provide some links which provides images of these three

Answer 1

BAND SPECTRUM-A spectrum consisting of groups or bands of closely spaced lines in emission or absorption, characteristic of molecular gases and chemical compounds.

LINE-A spectrum of radiation in which the quantity being studied, such as frequency or energy, takes on discrete values. Conventionally, the spectra of atoms, ions, and certain molecules in the gaseous phase at low pressures; distinguished from band spectra of molecules, which consist of a pattern of closely spaced spectral lines which could not be resolved by early spectroscopes.

CONTINUOUS-A spectrum having no lines or bands, especially a spectrum of radiation distributed over an uninterrupted range of wavelengths.

Answer 2

line spectrum is several energy levels separate to each other. For example the line spectrum of atom emission. When there are many energy levels close to each other, make it seen that the energy level is continues distribute, it form a band spectrum. Such as energy levels structure in solid state physics. When many atoms put together with fix array call lattic, the line spectum of atom will expend to band spectrum of solid.

Answer 3

The model of the electromagnetic spectrum pictured at the top of the previous page is used extensively in

textbooks and on posters, and like all other models it contains distortions. The model is extremely useful for

showing the frequencies of the different bands of electromagnetic radiation (EMR), and the relationships

between frequency and wavelength. However, this is a logarithmic scale, and severely distorts the actual width

of the different bands of radiation. The result is that looking at this model gives you the wrong idea that the

radio band is very large compared to the X-ray band, for example. You are going to construct both models,

logarithmic and linear, on the same chart and compare the two scales.

1. Tape four pieces of 8 1/2" by 11" paper together end-to-end so that their long sides are on the bottom. The

pieces of paper should overlap by 3 cm. Then draw a line down the left side of the chart about 2 cm from the

edge (see diagram below). From the line you have just drawn, draw two horizontal lines extending to the

right across the pages: one line 8 cm from the top of the chart, and the other line 10 cm below the first

horizontal line (see diagram below).

2. The top line will be used to plot the logarithmic scale. Along this line, mark off 24 1-cm intervals from the

vertical line you drew. Starting at 1 cm, label each interval with increasing powers of ten, from 101 to 1024.

These numbers represent the frequency in Hertz of the electromagnetic spectrum. Use the information from

the Frequency Range Table below to divide your scale into the individual bands of electromagnetic

radiation. (Use the entire visible band, not the individual colors.

Frequency Range Table

EMR Bands Frequency Range (Hertz) 1014 Conversions

Radio & Microwave Near 0 to 3.0 x 1012

Infrared 3.0 x 1012 to 4.6 x 1014

Visible 4.6 x 1014 to 7.5 x 1014 4.6 x 1014 to 7.5 x 1014

Red 4.6 x 1014 to 5.1 x 1014 4.6 x 1014 to 5.1 x 1014

Orange 5.1 x 1014 to 5.6 x 1014 5.1 x 1014 to 5.6 x 1014

Yellow 5.6 x 1014 to 6.1 x 1014 5.6 x 1014 to 6.1 x 1014

Green 6.1 x 1014 to 6.5 x 1014 6.1 x 1014 to 6.5 x 1014

Blue 6.5 x 1014 to 7.0 x 1014 6.5 x 1014 to 7.0 x 1014

Violet 7.0 x 1014 to 7.5 x 1014 7.0 x 1014 to 7.5 x 1014

Ultraviolet 7.5 x 1014 to 6.0 x 1016

X-ray 6.0 x 1016 to 1.0 x 1020

Gamma Ray 1.0 x 1020 to...

3. Before you can construct the linear scale, it is necessary to convert the frequencies that you

used for the logarithmic scale. Those numbers simply told you the range of frequencies, or

amount of energy, that each of the bands of EMR covers within the spectrum. Now we want

to compare the width of each of the individual bands of radiation relative to each other. We

can do this by converting all of the bands of EMR to the same frequency range. We will

arbitrarily select the frequency range of the visible band, 1014. Convert the frequency

numbers for all bands (except visible) in the Frequency Range Table above to 1014 and

record them in the table (see appendix 1 for tutorial on converting exponents).

4. Mark off 10 10-cm intervals from the vertical line. Starting at the first interval, label each

mark as a whole number times 1014, from 1 x 1014 to 10 x 1014. Label the bottom of your

model "Frequency in Hertz." You can now plot some of the 1014 frequencies you calculated

on the bottom line of your constructed model. Plot the individual colors of the visible

spectrum and color them. Compare the two scales. Do the results surprise you?

5. How far does the ultraviolet band extend? Calculate the width of the X-ray band. Do you

have enough string to measure the distance from the end of the ultraviolet band to the end of

the X-ray band? What do you think you would need to measure the distance to the end of the

X-ray part of the EMR?

6. X-rays are the next band of radiation. Calculate the distance from the end of the ultraviolet

band to the end of the X-ray band. Obtain a map from the Internet or use a local or state

highway map to plot the distance.

7. This URL will be useful in measuring the distance from the end of your string (the end of the

ultraviolet band) to the end of the X-ray band:

Yahoo! Maps http://maps.yahoo.com/py/maps.py

8. Based on your results for the width of the X-ray band, what would be your estimate for the

width of the gamma ray band of radiation? What would you need to measure the distance?

Appendix 1

Using Scientific Notation

We use methods such as abbreviations and acronyms to make long words or long phrases easier

to write. In this activity we have used the acronym EMR so we do not have to keep writing the

words "ElectroMagnetic Radiation". We use acronyms such as NASA so we do not have to write

out the words "National Aeronautics and Space Administration". We do the same thing with

numbers, by using scientific notation (exponents.) For example, the number 1,000,000 written in

scientific notation, or exponential form, is 1 x 106.

100 = 10 x 10 = 1 x 102

1000 = 10 x 10 x 10 = 1 x 103

10,000 = 10 x 10 x 10 x 10 x 10 = 1 x 105

What if we wanted to express the number 100 [1 x 102] as an exponent of 103? The difference

between 102 and 103 is one exponent so we would move the decimal one place. Since we are

expressing a number as a larger exponent, the decimal place is moved one place to the left, so 1 x

102 becomes 0.1 x 103

What if we wanted to express the number 10,000 [1 x 105] as an exponent of 103?

The difference between 105 and 103 is two exponents so we would move the decimal two places.

Since we are expressing a number as a smaller exponent, the decimal place is moved two places

to the right, so 1 x 105 becomes 100 x 103.