An electron in a vacuum chamber is fired with a speed of 9800 km/s toward a large, uniformly charged plate 75 cm away. the electron reaches a closest distance of 15 cm before being repelled.

The plate's surface charge density is

Explanation:

Given that,

Speed = 9800 km/s

Distance d= 75 cm

Distance d' =15 cm

Suppose we determine the plate's surface charge density?

We need to calculate the surface charge density

Using work energy theorem

Here, final velocity is zero

...(I)

We know that,

...(II)

From equation (I) and (II)

Charge is negative for electron

Put the value into the formula

Hence, The plate's surface charge density is

car stops. he keeps going = he has inertia