1
WB JEE 2023
MCQ (Single Correct Answer)
+2
-0.5
Change Language

There are n elastic balls placed on a smooth horizontal plane. The masses of the balls are $$\mathrm{m}, \frac{\mathrm{m}}{2}, \frac{\mathrm{m}}{2^{2}}, \ldots \frac{\mathrm{m}}{2^{\mathrm{n}-1}}$$ respectively. If the first ball hits the second ball with velocity $$\mathrm{v}_{0}$$, then the velocity of the $$\mathrm{n}^{\text {th }}$$ ball will be,

A
$$\frac{4}{3} v_{0}$$
B
$$\left(\frac{4}{3}\right)^{n} v_{0}$$
C
$$\left(\frac{4}{3}\right)^{n-1} v_{0}$$
D
$$\mathrm{v}_{0}$$
2
WB JEE 2023
MCQ (Single Correct Answer)
+2
-0.5
Change Language

An earth's satellite near the surface of the earth takes about 90 min per revolution. A satellite orbiting the moon also takes about $$90 \mathrm{~min}$$ per revolution. Then which of the following is true?

[where $$\rho_{\mathrm{m}}$$ is density of the moon and $$\rho_{\mathrm{e}}$$ is density of the earth.]

A
$$\rho_{\mathrm{m}}<\rho_{\mathrm{e}}$$
B
$$\rho_{m}>\rho_{e}$$
C
$$\rho_{m}=\rho_{e}$$
D
No conclusion can be made about the densities.
3
WB JEE 2023
MCQ (Single Correct Answer)
+2
-0.5
Change Language

WB JEE 2023 Physics - Magnetism Question 2 English

A bar magnet falls from rest under gravity through the centre of a horizontal ring of conducting wire as shown in figure. Which of the following graph best represents the speed (v) vs. time (t) graph of the bar magnet?

A
WB JEE 2023 Physics - Magnetism Question 2 English Option 1
B
WB JEE 2023 Physics - Magnetism Question 2 English Option 2
C
WB JEE 2023 Physics - Magnetism Question 2 English Option 3
D
WB JEE 2023 Physics - Magnetism Question 2 English Option 4
4
WB JEE 2023
MCQ (More than One Correct Answer)
+2
-0
Change Language

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?

A
The radius of nth orbit $$\mathrm{r_n~\infty ~\sqrt n}$$.
B
The minimum velocity of the electron is $$\frac{\sqrt{\mathrm{qB} \hbar}}{\mathrm{m}}$$.
C
Energy of the $$\mathrm{n}^{\text {th }}$$ level $$E_{n} ~\infty~n$$.
D
Transition frequency $$\omega$$ between two successive levels is independent of n.
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