An electron of mass 9.11×10-31kg leaves one end of a tv picture tube with zero initial speed and travels in a straight line to the accelerating grid, which is a distance 1.30cm away. it reaches the grid with a speed of 2.50×106m/s . the accelerating force is constant.
a)find the acceleration.
b)find the time to reach the grid.
c)find the net force. (you can ignore the gravitational force on the electron).

(A) Acceleration will be

(b) Time taken will be

(c) Force will be              

Explanation:

We have given that electron starts from rest so initial velocity u = 0 m/sec

Final velocity

Mass of electron

Distance traveled by electron

From third equation of motion we know that

(a) So

(b) From first equation of motion we know that v = u+at

So

(c) From newton's law we know that force

the answer is f1 and d2 because if you put equal force on those two points the beam would balance trust me on this

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.