Electrons Emerge from an Electron Gun with a Speed Of 2.0

Multiple Choice

Electrons emerge from an electron gun with a speed of $2.0 \times 10 ^ { 6 } \mathrm {~m} / \mathrm { s }$ and then pass through a double-slit apparatus. Interference fringes with spacing of $2.7 \mathrm {~mm}$ are detected on a screen far from the double slit. What would the fringe spacing be if the electrons were replaced by neutrons with the same speed? $\left( h = 6.626 \times 10 ^ { - 34 } \mathrm {~J} \cdot \mathrm { s } , m _ { \text {electron } } = 9.11 \times 10 ^ { - 31 } \mathrm {~kg} , m _ { \text {neutron } } = 1.675 \times \right.$ 10-27 $\mathrm { kg }$ )

A) $0.93 \mathrm {~nm}$
B) $4.9 \mathrm {~m}$
C) $1.2 \mathrm {~km}$
D) $1.5 \mu \mathrm { m }$