CBSE Class 12 Physics 2022 Term 2 Outside Delhi Set 1 Solved Paper

Question : 9

Total: 12

An electron is accelerated from rest through a potential difference of 100V.
Find:
(i) the wavelength associated with
(ii) the momentum and
(iii) the velocity required by the electron. 3

Solution:

(i) Wavelength =λ=

√2meV

∴λ=

6.6×10−34

√2×9.1×1031×1.6×10−19×100

=1.2×10−10m=1.2Å
(ii) Momentum =p=

∴p=

6.6×10−34

1.2×10−10

=5.5×10−24kgm∕s
(iii) Momentum = p=mv
∴ Velocity =v=

=5.5×

10−24

9.1

×10−31
=6×106m∕s

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