1
JEE Main 2020 (Online) 4th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
The driver of a bus approaching a big wall notices that the frequency of his bus's horn changes from 420 Hz to 490 Hz when he hears it after it gets reflected from the wall. Find the speed of the bus if speed of the sound is 330 ms–1.
A
91 kmh–1
B
81 kmh–1
C
61 kmh–1
D
71 kmh–1
2
JEE Main 2020 (Online) 4th September Morning Slot
MCQ (Single Correct Answer)
+4
-1
For a transverse wave travelling along a straight line, the distance between two peaks (crests) is 5 m, while the distance between one crest and one trough is 1.5 m. The possible wavelengths (in m) of the are :
A
1, 3, 5, .....
B
$${1 \over 1},{1 \over 3},{1 \over 5},$$ .....
C
1, 2, 3, .....
D
$${1 \over 2},{1 \over 4},{1 \over 6},$$
3
JEE Main 2020 (Online) 3rd September Morning Slot
MCQ (Single Correct Answer)
+4
-1
A uniform thin rope of length 12 m and mass 6 kg hangs vertically from a rigid support and a block of mass 2 kg is attached to its free end. A transverse short wavetrain of wavelength 6 cm is produced at the lower end of the rope. What is the wavelength of the wavetrain (in cm) when it reaches the top of the rope ?
A
12
B
3
C
9
D
6
4
JEE Main 2020 (Online) 2nd September Morning Slot
MCQ (Single Correct Answer)
+4
-1
An amplitude modulated wave is represented by the expression
vm = 5(1 + 0.6 cos 6280t) sin(211 × 104 t) volts
The minimum and maximum amplitudes of the amplitude modulated wave are, respectively
A
$${3 \over 2}$$ V, 5 V
B
$${5 \over 2}$$ V, 8 V
C
5 V, 8 V
D
3 V, 5 V
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