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The speed of electromagnetic waves (which include visible light, radio, and x rays) in vacuum is30x108m/s. (a) Wavelengths of visible light waves range from about 700 nmin the violet to about 700 nmin the red. What is the range of frequencies of these waves? (b)The range of frequencies for shortwave radio (for example, FM radio and VHF television) is 1.5to 300 MHz . What is the corresponding wavelength range? (c) X-ray wavelengths range from about 5.0nmto about1.0x10-2nm . What is the frequency range for x rays?

Short Answer

Expert verified
  1. Range of frequencies is 4.3×1014Hzand7.5×1014Hz
  2. Wavelength range is1.0mand2.0×102m
  3. Frequency range for x rays is 6.0×1016Hzand3.0×1019Hz

Step by step solution

01

Given data

Speed of electromagnetic wave,c=3.00×108m/s

Wavelength of visibleλ1=400nmor400×10-9m

Wavelength of visible lightλ2=700nmor700×10-9m

Frequency ranges,f=1.5to300MHz

X ray wavelength range is 5.0nmor1.0×10-2nm

02

Understanding the concept of resonant frequency

Here we have to use the basic formula for wave velocity in terms of wavelength and frequency.

Formula:

The speed of light, c=fλ....…1

03

Step 3(a): Calculation of range of frequencies

Using equation (1), we get the value of maximum frequency of visible light for first wavelength as:

f1=vλ1=3.00×108400×10-9=7.5×1014Hz

Now minimum frequencyf2using equation (1) is given as follows:

localid="1660992239723" f2=vλ2=3.00×108700×10-9=4.3×1014Hz.

Hence, the range of frequencies is 4.3×1014Hzand7.5×1014Hz

04

Step 4(b): Calculation of wavelength range

Now using minimum frequency and equation (1), we get the wavelengthλ1as:

λ1=3.00×108300×106=1.0m.

Now using maximum frequency and equation (1), we get the wavelengthλ2as:

λ2=3.00×1081.5×106=200m

Hence, the value of wavelength range is 1.0mand2.0×102m

05

Step 5(c): Calculation of frequency range for x-rays

Now minimum frequencyf1using equation (1) for x-rays is given as:

f1=3.00×1085×10-9=6.0×1016Hz

Now maximum frequencyf2using equation (1) for x-rays is given as:

f2=3.00×1081.0×10-11=3.0×1019Hz

Hence, the value of frequency range for x rays is6.0×1016Hzand3.0×1019Hz

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