An X-ray tube operates at 40 kV with current 10 mA. Only 1% of the incident-electron kinetic-energy power becomes X-rays. Find the X-ray power in watt.
Physics · Mixed Chapter
JEE Mains

Question

An X-ray tube operates at 40 kV with current 10 mA. Only 1% of the incident-electron kinetic-energy power becomes X-rays. Find the X-ray power in watt.

G1 Physics · Accepted Answer

Step 1 — Electrical input power delivered to the electron beam: P₁ = VI = 40,000 V × 0.010 A = 400 W. Step 2 — Conversion efficiency: Only η = 1/100 = 0.01 becomes X-rays. Step 3 — X-ray power: Pₓ = ηP₁ = 0.01×400 = 4 W. Answer: 4.