1
WB JEE 2025
MCQ (Single Correct Answer)
+1
-0.25
Change Language
For a domestic AC supply of 220 V at 50 cycles per sec, the potential difference between the terminals of a two-pin electric outlet in a room is given by
A
$\mathrm{V}(\mathrm{t})=220 \sqrt{2} \operatorname{Cos}(100 \pi \mathrm{t})$
B
$V(t)=220 \operatorname{Sin}(50 t)$
C
$\mathrm{V}(\mathrm{t})=220 \operatorname{Cos}(100 \pi \mathrm{t})$
D
$\mathrm{V}(\mathrm{t})=220 \sqrt{2} \operatorname{Cos}(50 \mathrm{t})$
2
WB JEE 2025
MCQ (Single Correct Answer)
+1
-0.25
Change Language

A radioactive nucleus decays as follows :

$$ X \xrightarrow{\alpha} X_1 \xrightarrow{\beta} X_2 \xrightarrow{\alpha} X_3 \xrightarrow{\gamma} X_4 $$

If the mass number and atomic number of ' $X_4$ ' are 172 and 69 respectively, then the atomic number and mass number of ' $X$ ' are

A
72,180
B
69,170
C
68,172
D
70,172
3
WB JEE 2025
MCQ (Single Correct Answer)
+1
-0.25
Change Language

A single slit diffraction pattern is obtained using a beam of red light. If red light is replaced by blue light then

A
the diffraction pattern will disappear.
B
fringes will become narrower and crowded together.
C
fringes will become broader and will be further apart.
D
there is no change in the diffraction pattern.
4
WB JEE 2025
MCQ (Single Correct Answer)
+1
-0.25
Change Language

The variation of density of a solid cylindrical rod of cross sectional area $\alpha$ and length $L$ is $\rho=\rho_0 \frac{x^2}{L^2}$, where $x$ is the distance from one end of the rod. The position of its centre of mass from one end $(x=0)$ is

WB JEE 2025 Physics - Center of Mass Question 2 English

A
$\frac{2 L}{3}$
B
$\frac{L}{2}$
C
$\frac{L}{3}$
D
$\frac{3 L}{4}$
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