Q219 · Practice questionComplex familiar1 mark
QUESTION 219
A non-relativistic electron beam's kinetic energy is increased by a factor of four. How does its de Broglie wavelength change?
(A)
It becomes four times as large.
(B)
It doubles.
(C)
It becomes one quarter as large.
(D)
It halves.
WORKED SOLUTION
1 markAnswer D
ANSWER
D. It halves.
Worked solution
For a fixed mass, , so increasing kinetic energy fourfold doubles momentum. Since , wavelength halves. This uses the stated non-relativistic regime.
Equivalent physically justified methods and consistent equivalent units accepted.
Displayed decimals are model answers; accept appropriate significant figures and consistent rounding from stated constants.
Select D.
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