Question

An electron (m = 9.1 × 10−31 kg, q = −1.6 × 10−19 C) starts from rest at point A and has a speed of 5.0 × 106 m/s at point B. Only electric forces act on it during this motion. Determine the electric potential difference VA − VB.a) −71 Vb) +71 Vc) −26 Vd) +26 Ve) −140 V

Answer 1

-71 V

Step-by-step explanation:

Given that,

An electron starts from rest at point A and has a speed of 5.0 × 10⁶ m/s at point B.

We need to find the electric potential difference
`V_A-V_B`. It can be calculated by using the conservation of charges as follows :

`qV=(1)/(2)mv^2`

m and q are mass and charge on electrons

`V=(mv^2)/(2(-q))\\\\V=-(9.1* 10^(-31)* (5* 10^6)^2)/(2* 1.6* 10^(-19))\\\\V=-71.09\ V`

So, the electric potential difference is (-71 V). So, the correct option is (a).