Question

Identify the correct statements(s):

• A. Wavelength associated with a 1 kg ball moving with the velocity 100 m/s can't be calculated
• B. Wave nature of the running train is difficult to obseve because wavelength is extremely small
• C. Wavelength associated with the electron can be calulated using the formula $E=\frac{hc}{\lambda }$
• D. If an electron is accelerated through 20 V potential difference, if it has already 5 eV kinetic energy then wavelength of the electron is approximately $\sqrt{6}\stackrel{o}{A}$

Answer 1

Answer: (B), (D)

The correct options are
B Wave nature of the running train is difficult to obseve because wavelength is extremely small
D If an electron is accelerated through 20 V potential difference, if it has already 5 eV kinetic energy then wavelength of the electron is approximately $\sqrt{6}\stackrel{o}{A}$

(A) $\lambda$ can be calculated as: $\lambda =\frac{h}{mv}=\frac{6.626\times {10}^{-34}}{1\times 100}=6.626\times {10}^{-36}m.$

$\lambda$ comes out to be very small.

(B) Heisenberg's principle is applicable for microscopic objects. So, wave nature of the running train is difficult to observe because wavelength is extremely small.

(C) de-Broglie wavelength associated with electron can be calculated by using $\lambda =\frac{h}{mv}$.

$\left(D\right)K{E}_f=5+20=25eV$
$\therefore \lambda =\sqrt{\frac{150}{K{E}_f}}=\sqrt{\frac{150}{25}}=\sqrt{6}\stackrel{o}{A}$