1
WB JEE 2026
MCQ (More than One Correct Answer)
+1
-0.25
Change Language

Radiation of wavelength $\lambda$ is incident on a photocell.The fastest emitted electron has speed $v$ . If the wavelength is changed to $\frac{3 \lambda}{4}$ ,then the speed of the fastest emitted electron will be

A

greater than $v \sqrt{\frac{4}{3}}$

B

less than $v \sqrt{\frac{4}{3}}$

C

equal to $v \sqrt{\frac{4}{3}}$

D

equal to $v \sqrt{\frac{3}{4}}$

2
WB JEE 2026
MCQ (More than One Correct Answer)
+1
-0.25
Change Language

Two spherical soap bubbles of radii $r_1$ and $r_2$ in vaccum coalesce under isothermal condition.The newly formed bubble has a radius( $r$ )given by

A

$r_1+r_2$

B

$\frac{r_1+r_2}{2}$

C

$\frac{r_1 r_2}{r_1+r_2}$

D

$\sqrt{r_1^2+r_2^2}$

3
WB JEE 2026
MCQ (More than One Correct Answer)
+1
-0.25
Change Language

A radioactive element ${ }_{92}^{242} \mathrm{X}$ emits two $\alpha$-particles,one electron and two positrons.The transformed nucleus is represented by ${ }_P^{234} Y$ .The value of $P$ is

A

85

B

87

C

92

D

96

4
WB JEE 2026
MCQ (More than One Correct Answer)
+1
-0.25
Change Language

The magnetic moment of an iron bar is $M$. It is now bent in such a way that it forms an arc section of a circle subtending an angle of $60^{\circ}$ at the centre. The magnetic moment of the arc section is

A

$\frac{3 M}{\pi}$

B

$\frac{4 M}{\pi}$

C

$\frac{M}{\pi}$

D

$\frac{2 M}{\pi}$