Question

The kinetic energy of the electron is E when the incident wavelength is λ. To increase the K.E. of the electron to 2E, the incident wavelength must be

• A. 2λ
• B. λ/2
• C.
• D.

Answer 1

Answer: (C)

Answer 2

E = φ + k_m ⇒ $\frac { \mathrm { hc } } { \lambda }$ = φ + k_m