1
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.
2
WB JEE 2023
MCQ (More than One Correct Answer)
+2
-0
Change Language

A train is moving along the tracks at a constant speed u. A girl on the train throws a ball of mass m straight ahead along the direction of motion of the train with speed $$\mathrm{v}$$ with respect to herself. Then

A
Kinetic energy of the ball as measured by the girl on the train is $$\mathrm{mv}^{2} / 2$$.
B
Work done by the girl in throwing the ball is $$ \mathrm{mv}^{2} / 2$$.
C
Work done by the train is mvu.
D
The gain in kinetic energy of the ball as measured by a person standing by the rail track is $$\mathrm{mv}^{2} / 2$$.
3
WB JEE 2023
MCQ (More than One Correct Answer)
+2
-0
Change Language

WB JEE 2023 Physics - Heat and Thermodynamics Question 6 English

A cyclic process is shown in p-v diagram and T-S diagram. Which of the following statements is/are true?

A
1$$\to$$2 : Isobaric, 2$$\to$$3 : Isothermal.
B
3$$\to$$1 : Isochoric, 2$$\to$$3 : adiabatic.
C
Work done by the system in the complete cyclic process is non-zero.
D
The heat absorbed by the system in the complete cyclic process is non-zero.
4
WB JEE 2023
MCQ (More than One Correct Answer)
+2
-0
Change Language

WB JEE 2023 Physics - Capacitor Question 3 English

The figure shows two identical parallel plate capacitors A and B of capacitances C connected to a battery. The key K is initially closed. The switch is now opened and the free spaces between the plates of the capacitors are filled with a dielectric constant 3. Then which of the following statements is/are true?

A
When the switch is closed, total energy stored in the two capacitors is CV$$^2$$.
B
When the switch is opened, no charge is stored in the capacitor B.
C
When the switch is opened, energy stored in capacitor B is $$\frac{3}{2}$$CV$$^2$$.
D
When the switch is opened, total energy stored in two capacitors is $$\frac{5}{3}$$CV$$^2$$.
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