1
COMEDK 2026 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0

A hydrogen atom absorbs energy and rises to $n=3$ state from its ground state $n=1$. If the potential energy of the atom at its ground state is -13.6 eV , find the wave length emitted by it when it returns to its ground state:

{Planck's constant $=6.6 \times 10^{34} \mathrm{~J} \mathrm{~s}$ }

A

$12000^{\circ} \mathrm{A}$

B

$1020^{\circ} \mathrm{A}$

C

$7000^{\circ} \mathrm{A}$

D

$4000^{\circ} \mathrm{A}$

2
COMEDK 2026 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0

On both sides of a magnetic needle, two short magnets A and B are placed on the same horizontal line which is perpendicular to the magnetic meridian. The south poles of $A$ and $B$ are facing each other, which are 10 cm and 20 cm respectively from the magnetic needle. If the needle remains undeflected, the ratio of the magnetic moment of $A$ to that $B$ is:

A

$2:1$

B

$8:1$

C

$1: 8$

D

$1: 2$

3
COMEDK 2026 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0

A parallel combination of ' $n$ ' cells of emf ' $E$ ' and internal resistance ' $r$ ' each, are connected across the external resistance ' $R$ '. If the external resistance ' $R$ ' is negligibly small, then the current ' $I$ ' through the external resistance is:

A

$I=\frac{E}{n R}$

B

$I=\frac{E}{R}$

C

$I=\frac{n E}{R}$

D

$I=\frac{r E}{n}$

4
COMEDK 2026 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0

A particle moves along a parabolic path $y=9 x^2$ in such a way that the x component of velocity remains constant. If, the acceleration of the particle is $2 j m s^{-2}$, find the x component of velocity.

A

$\frac{1}{9} m s^{-1}$

B

$\frac{1}{4} m s^{-1}$

C

$\frac{1}{3} m s^{-1}$

D

$\frac{1}{6} m s^{-1}$