Question

An X-ray tube is operated at 15 kV. Calculate the upper limit of the speed of the electrons striking the target.

• A. 7.26×10⁷ m/s
• B. 7.62×10⁷ m/s
• C. 7.62×10⁹ m/s
• D. 7.26×10⁹ m/s

Hint:

Maximum electron speed is calculated assuming all electrical energy converts to kinetic energy.

Answer 1

The Correct Option is A

Step 1: Maximum kinetic energy of electron, Kₐₓ=eV=1.6×10⁻¹⁹×15000=2.4×10⁻¹⁵ J
Step 2: Using K=(1)/(2)mv², v=√((2K)/(m))=√2×2.4×10⁻¹⁵9.11×10⁻³¹
Step 3: v=7.26×10⁷ m/s