1
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
An EM wave of frequency $5 \times 10^9 \mathrm{~Hz}$ falls normally on a rectangular slit of width 3 cm . What is the total angular width of the central maxima?
A
8 rad
B
2 rad
C
4 rad
D
0.25 rad
2
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
Two wires A and B made of same material having length 10 cm and 40 cm respectively are connected in parallel to the same source of emf 10 V . What will be the ratio of the drift velocity of the electrons in the wire $A$ to the drift velocity in the wire $B$ ?
A
$\frac{V_{d A}}{V_{d B}}=1: 4$
B
$\frac{V_{d A}}{V_{d B}}=1: 2$
C
$\frac{V_{d A}}{V_{d B}}=4: 1$
D
$\frac{V_{d A}}{V_{d B}}=2: 1$
3
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
When a metallic spherical shell of radius 20 cm is charged, the potential on its surface is found to be 5 V . The potential at a point 10 cm from the centre of the spherical shell is :
A
10 V
B
2.5 V
C
1.25 V
D
5 V
4
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
What is the maximum wave length of EM radiation required to move an electron from the valance band to conduction band of a semiconductor? [Given :Energy gap $\mathrm{E}_{\mathrm{g}}=1.98 \times 10^{-19} \mathrm{~J}$; Planck's constant $h=6.6 \times 10^{-34} \mathrm{Js}$ ]
A
$10^{-9} \mathrm{~m}$
B
$10^{-6} \mathrm{~m}$
C
$10^{-10} \mathrm{~m}$
D
$10^{-12} \mathrm{~m}$
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