The electron gun m an old TV picture tube accelerates electrons between two para

Question

The electron gun m an old TV picture tube accelerates electrons between two parallel plates 1.2 cm apart with a 30 kV potential difference between them The electrons enter through a small hole in the negative plate, accelerate, then exit trough a small hole in the positive plate Assume that the holes are small enough not to affect the electric fold or potential. What is the electric field strength between the plates? Express your answer to two significant figures and Include the appropriate units. With what speed does an electron exit the electron gun if its entry speed is done to zero.? The exit speed is so fast that we really need to use the theory of relativity to compute an accurate value. your answer to part B is in the right range but a little too big. Express your answer to two significant figures and include the appropriate units.

Explanation / Answer

a) Electric field strength is a quantitative expression of the intensity of an electric field at a particular location. The standard unit is the volt per meter.Electric field strength is given by VOLTAGE DIFFERENCE/LENGTH

here it is E = 30kv/1.2cm= 2500kv/mt

b)work done by electric field is change in kinetic energy of electron i.e

q.E.d=0.5mv2

1.6*10-19*2500*0.012 = 0.5*9.1*10-31*v2

v=3247991.772 very large> speed of light

after applying theory of relativity it will come below speed of light

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