Calculate the value of the wavelength, Electrical Engineering

Assignment Help:

In an electron microscope, a beam of electrons is produced by a device called an electron gun. In the electron gun, electrons are 'boiled off' from a heated filament (which is the cathode and held at high negative voltage) and are attracted towards an anode. The high voltage difference ΔV causes the electrons to accelerate.

(i) Assuming that the speed of the electrons is zero as they are emitted from the filament and that as they reach the anode it is v, find an expression relating the final speed v to the charge on an electron, the mass of an electron and ΔV, and hence calculate the speed v of the electrons after passing through a voltage difference of 120 kV. You should identify clearly the three main steps in your answer ('Decide how you are going to tackle the problem'; 'Do the calculation'; 'Check that your answer makes sense') and you should state any assumptions that you make. You should show all of your working.

(ii) The wavelength, λ, of a beam of electrons is related to the speed, v, and mass, m, of the electrons by the following equation:

 λ, = h/mv

      where h is the Planck constant. Use this equation and your answer to part (i) to show that the wavelength λ of the electrons is related to the high voltage difference ΔV by the following equation:

λ2, = h2/2emΔV

(iii) Calculate the value of the wavelength of a beam of electrons in a microscope operated at 120 kV as in (i) and also at 15 kV. Your working should show explicitly how you arrived at units of length (metres) for your answers.

(iv) Compare the speed you calculated in part (i) with the speed of light and hence comment on the reasons why your calculated results may be inaccurate.


Related Discussions:- Calculate the value of the wavelength

Determine the percent voltage regulation of the transformer, The transforme...

The transformer of Example is supplying full load (i.e., rated load of 50 kVA) at a rated secondary voltage of 240 V and 0.8 power factor lagging. Neglecting the exciting current o

generator, diagram of static generator

diagram of static generators

Estimate the the volume of water in the tank, A conical tank is shown in Fi...

A conical tank is shown in Figure. The tank is filled with water.  Using MATLAB, determine: a.   the volume of water in the tank b.   the weight of the water in the tank.

Applications of semiconductors, Applications of Semiconductors Inte...

Applications of Semiconductors Integrated circuits (ICs) SSI, MSI, LSI, and VLSI. Fluorescent materials used in TV screens II-VI (ZnS). Light detectors InSb, CdSe, Pb

Explain briefly programmable interval timer 8254, Explain with proper diagr...

Explain with proper diagram all the six modes of operation of programmable interval timer 8254. Mode 0: The output in mode 0 is initially low, and will stay low for the perio

Determine the expected voltage levels at the output, The subsequent voltage...

The subsequent voltage-source multiplying DAC is to be utilized to convert the digital data stream "11" and "01" to an analog signal.  It has 2-bit inputs and hence is capable of c

Explain shockly''s equation and its significance, Q. Explain shockly's equa...

Q. Explain shockly's equation and its significance in plotting the transfer characteristics ? The linear relationship does not exists in the output of the JFET, the relationshi

Explain the properties of high resistive materials, Explain the properties ...

Explain the properties of high resistivity materials. High resistivity materials: The conducting materials containing resistivity from 10 -6 to 10 -3 ohm-m come under such

Square wave generator ( 10 MHz to 20MHz), I need a simple design of above ...

I need a simple design of above mentioned , this oscillator will be used in a wireless power transmission

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd