Question

the speed of fast moving electron having total energy of 2 mev is???

Answer 1

Kinetic Energy = 2 MeV = 2 × 1.6 × 10⁻¹³J

= 3.2 × 10⁻¹³J  

Mass of the Electrons  = 9.1 × 10⁻³¹ Kg.

Using the Formula,

K.E. = 1/2 mv²

3.2 × 10⁻¹³ = 1/2 × 9.1 × 10⁻³¹ × v²

⇒ v² = 0.7 × 10¹⁸

∴ v = 8.4 × 10⁸ m/s.

Hope it helps.

Answer 2

Kinetic Energy = 2 MeV = 2 × 1.6 × 10⁻¹³J

= 3.2 × 10⁻¹³J  

Mass of the Electrons  = 9.1 × 10⁻³¹ Kg.


Using the Formula,

K.E. = 1/2 mv²

3.2 × 10⁻¹³ = 1/2 × 9.1 × 10⁻³¹ × v²

⇒ v² = 0.7 × 10¹⁸

∴ v = 8.4 × 10⁸ m/s.