WB JEE 2023 | Atoms and Nuclei Question 5 | Physics

WB JEE 2023

MCQ (More than One Correct Answer)

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A uniform magnetic field B exists in a region. An electron of charge q and mass m moving with velocity v enters the region in a direction perpendicular to the magnetic field. Considering Bohr angular momentum quantization, which of the following statements is/are true?

The radius of n^th orbit $$\mathrm{r_n~\infty ~\sqrt n}$$.

The minimum velocity of the electron is $$\frac{\sqrt{\mathrm{qB} \hbar}}{\mathrm{m}}$$.

Energy of the $$\mathrm{n}^{\text {th }}$$ level $$E_{n} ~\infty~n$$.

Transition frequency $$\omega$$ between two successive levels is independent of n.

WB JEE 2022

MCQ (More than One Correct Answer)

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A sample of hydrogen atom in its ground state is radiated with photons of 10.2 eV energies. The radiation from the sample is absorbed by excited ionized He⁺. Thenwhich of the following statement/s is/are true?

He⁺ electron moves from n = 2 to n = 4.

In the He⁺ emission spectra, there will be 6 lines.

Smallest wavelength of He⁺ spectrum is obtained when transition taken place from n = 4 to n = 3.

He⁺ electron moves from n = 2 to n = 3.

WB JEE 2017

MCQ (More than One Correct Answer)

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Let v_n and E_n be the respective speed and energy of an electron in the nth orbit of radius r_n, in a hydrogen atom, as predicted by Bohr's model. Then

plot of $${{{E_n}{r_n}} \over {{E_1}{r_1}}}$$ as a function of n is a straight line of slope 0

plot of $${{{r_n}{v_n}} \over {{r_1}{v_1}}}$$ as a function of n is a straight line of slope 1

plot of ln$$\left( {{{{r_n}} \over {{r_1}}}} \right)$$ as a function of ln (n) is a straight line of slope 2

plot of ln $$\left( {{{{r_n}{E_1}} \over {{E_n}{r_1}}}} \right)$$ as a function of ln (n) is a straight line of slope 4

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