WAEC Physics 2020 Objective — Question 42
Question 42 of 50 from the West African Examinations Council (WAEC) Physics 2020 Objective paper, with the correct answer and a full explanation.
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An electron of mass 9.1x10^-31 kg is travelling at a speed of 2.0x10^6 m/s. Calculate the associated wavelength of the electron. [h=6.6x10^-34 J s]
- A. 3.63x10^-10 mCorrect
- B. 3.63x10^-8 m
- C. 3.63x10^-7 m
- D. 6.89x10^-4 m
Explanation
Given me=9.1x10^-31kg, v=2.0x10^6m/s, h=6.6x10^-34Js. Using the De-Broglie wavelength lambda=h/p, where p=momentum=mv: lambda=h/(mv)=6.6x10^-34/(9.1x10^-31 x 2x10^6)=3.63x10^-10 m.
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