Question

In producing X-rays a beam of electrons accelerated by a potential difference V is made to strike a metal target. For what value of V, X-rays will have the lowest wavelength of 0.3094 Å.

• A. 10 kV
• B. 20 kV
• C. 30 kV
• D. 40 kV

Answer 1

Answer: (D)

40 kV

Answer 2

From the formula $V = \frac { 12375 } { \lambda _ { \min } } = \frac { 12375 } { 0.3094 }$

$= 39.99kV \approx 40kV$.