An electron gun inside a computer monitor sends an electron toward the screen at a speed of 1.20 × 10⁸ m/s. If the mass of the electron is 9.109 × 10^-³¹ kg, what is the magnitude of its relativistic momentum?

Question

Quizplus · Accepted Answer

The relativistic momentum of an object is given by:
p = gamma*m*v
where gamma is the Lorentz factor, m is the mass of the object, and v is its velocity.
The Lorentz factor is given by:
gamma = 1/sqrt(1 - (v^2/c^2))
where c is the speed of light.
Substituting the given values, we get:
gamma = 1/sqrt(1 - (1.20 × 10^18)^2/(3.00 × 10^8)^2) ≈ 5.30
p = (5.30)(9.109 × 10^-31 kg)(1.20 × 10^18 m/s) ≈ 7.22 × 10^-12 kg m/s
Rounding to two significant figures, the answer is 1.19 × 10^-11 kg m/s, which corresponds to option C.

An Electron Gun Inside a Computer Monitor Sends an Electron