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

A silicon sample is doped simultaneously with donor impurity phosphorus at a concentration of $N_D=3 \times 10^{22} \mathrm{~m}^{-3}$ and acceptor impurity boron at a concentration of $N_D=2.8 \times 10^{22} \mathrm{~m}^{-3}$. The intrinsic carrier concentration of silicon at room temperature is $n_i=1.5 \times 10^{16} \mathrm{~m}^{-3}$. Assuming complete ionization, the hole concentration is :

A
$1.125 \times 10^{10} m^{-3}$
B
$1.125 \times 10^{11} \mathrm{~m}^{-3}$
C
$2.125 \times 10^{10} \mathrm{~m}^{-3}$
D
$2.125 \times 10^{11} m^{-3}$
2
COMEDK 2026 Morning Shift
MCQ (Single Correct Answer)
+1
-0

The velocity of a body moving in a viscous medium is given by $v=\frac{A}{B+C}\left[1-e^{\frac{-t}{B}}\right]$ where $t$ is time; dimensions of $A$ and $C$ are

A

$\left[\mathrm{M}^0 \mathrm{~L}^1 \mathrm{~T}^0\right],\left[\mathrm{M}^0 \mathrm{~L}^0 \mathrm{~T}^1\right]$

B

$\left[\mathrm{M}^0 \mathrm{~L}^1 \mathrm{~T}^1\right],\left[\mathrm{M}^0 \mathrm{~L}^0 \mathrm{~T}^1\right]$

C

$\left[\mathrm{M}^1 \mathrm{~L}^1 \mathrm{~T}^0\right],\left[\mathrm{M}^0 \mathrm{~L}^0 \mathrm{~T}^{-1}\right]$

D

$\left[\mathrm{M}^1 \mathrm{~L}^1 \mathrm{~T}^1\right],\left[\mathrm{M}^0 \mathrm{~L}^0 \mathrm{~T}^1\right]$

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

A proton is moving along negative $X$ axis. If a uniform magnetic field is applied parallel to the positive $Z$ axis, then choose the correct answer from the following options;

  1. The proton will experience magnetic force along positive Y direction and will move along a circular path in the XY plane

  2. The proton will experience magnetic force along negative Y direction and will move along a circular path in the XY plane

  3. The proton will experience magnetic force along positive Y direction and will move along a circular path in the XZ plane

  4. The proton will experience magnetic force along negative Y direction and will move along a circular path in the XZ plane

A

4

B

2

C

1

D

3

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

The magnetic field at the centre of a wire loop formed by two semicircular wires of radii $r_1=3.14 \mathrm{~m}$ and $r_2=6.28 \mathrm{~m}$ and carrying a current of $\mathrm{I}=2 \mathrm{~A}$ is:

COMEDK 2026 Morning Shift Physics - Moving Charges and Magnetism Question 6 English
A

$6 \times 10^{-7} T$

B

$2 \times 10^{-7} T$

C

$3 \times 10^{-7} T$

D

$4 \times 10^{-7} T$