1
MCQ (Single Correct Answer)

JEE Main 2016 (Online) 9th April Morning Slot

Two engines pass each other moving in opposite directions with uniform speed of 30 m/s. One of them is blowing a whistle of frequency 540 Hz. Calculate the frequency heard by driver of second engine before they pass each other. Speed of sound is 330 m/sec :
A
450 Hz
B
540 Hz
C
648 Hz
D
270 Hz

Explanation

Frequency heard by the driver of second engine,

F' = $$\left( {{{v + {v_0}} \over {v - {v_S}}}} \right)$$ f

given v0 = vs = 30 m/s

$$ \therefore $$   f'  = $$\left( {{{330 + 30} \over {330 - 30}}} \right) \times 540$$

=   648 Hz
2
MCQ (Single Correct Answer)

JEE Main 2016 (Online) 10th April Morning Slot

A toy-car, blowing its horn, is moving with a steady speed of 5 m/s, away from a wall. An observer, towards whom the toy car is moving, is able to hear 5 beats per second. If the velocity of sound in air is 340 m/s, the frequency of the horn of the toy car is close to :
A
680 Hz
B
510 Hz
C
340 Hz
D
170 Hz

Explanation



Let the frequency of the horn = f

Apparent frequency heared by the observer directly,

$${f_{dir}} = \left( {{V \over {V - {V_s}}}} \right)f = \left( {{{340} \over {340 - 5}}} \right)f = {{340} \over {335}}f$$

Apparent frequency heared by the observer on reflection from the wall,

$${f_{ind}} = \left( {{V \over {V + {V_s}}}} \right)f = \left( {{{340} \over {340 + 5}}} \right)f = {{340} \over {345}}f$$

Also, given that,

find $$-$$ fdir $$=$$ 5

$$ \Rightarrow $$   $${{340f} \over {345}}$$ $$-$$ $${{340f} \over {335}}$$ $$=$$ 5

$$ \Rightarrow $$   f $$=$$ $${5 \over {340}} \times {{335 \times 345} \over {10}}$$

= 169.9  $$ \simeq $$   170 Hz
3
MCQ (Single Correct Answer)

JEE Main 2017 (Offline)

A particle is executing simple harmonic motion with a time period T. At time t = 0, it is at its position of equilibrium. The kinetic energy – time graph of the particle will look like:
A
B
C
D

Explanation

For a particle executing SHM

At mean position; t = 0, $$\omega $$t = 0, y = 0, V = Vmax = a$$\omega $$

$$ \therefore $$ K.E = K.Emax = $${1 \over 2}m{\omega ^2}{a^2}$$

At extreme position : t = $${T \over 4}$$ , $$\omega $$t = $${\pi \over 2}$$ , y = A, V = Vmin = 0

$$ \therefore $$ K.E = K.Emin = 0

Hence graph (A) correctly represents kinetic energy - time graph.
4
MCQ (Single Correct Answer)

JEE Main 2017 (Online) 8th April Morning Slot

Two wires W1 and W2 have the same radius r and respective densities $$\rho $$1 and $$\rho $$2 such that ρ2 = 4$$\rho $$1 . They are joined together at the point O, as shown in the figure. The combination is used as a sonometer wire and kept under tension T. The point O is midway between the two bridges. When a stationary wave is set up in the composite wire, the joint is found to be a node. The ratio of the number of antinodes formed in W1 to W2 is :

A
1 : 1
B
1 : 2
C
1 : 3
D
4 : 1

Explanation

Fundamental frequency of a stretched string is ,

    f = $${n \over {2L}}\sqrt {{T \over \mu }} $$

Here, n = number of antinodes

$$\mu $$ = mass per unit length.

As, O is the midpoint of two bridegs, hence length of two wires are equal.

$$\therefore\,\,\,$$ L1 = L2 = L

As frequency of both wires same

f1 = f2

$$ \Rightarrow $$$$\,\,\,$$ $${{{n_1}} \over {2L}}\sqrt {{T \over {\pi {r^2}{\rho _1}}}} $$ = $${{{n_2}} \over {2L}}\sqrt {{T \over {\pi {r^2}{\rho _2}}}} $$

$$ \Rightarrow $$$$\,\,\,$$ $${{{n_1}} \over {{n_2}}}$$ = $$\sqrt {{{{\rho _1}} \over {{\rho _2}}}} $$

$$ \Rightarrow $$$$\,\,\,$$ $${{{n_1}} \over {{n_2}}}$$ = $$\sqrt {{{{\rho _1}} \over {4{\rho _1}}}} $$ = $${1 \over 2}$$

Questions Asked from Waves

On those following papers in MCQ (Single Correct Answer)
Number in Brackets after Paper Name Indicates No of Questions
AIEEE 2002 (5)
keyboard_arrow_right
AIEEE 2003 (3)
keyboard_arrow_right
AIEEE 2004 (1)
keyboard_arrow_right
AIEEE 2005 (2)
keyboard_arrow_right
AIEEE 2006 (2)
keyboard_arrow_right
AIEEE 2007 (1)
keyboard_arrow_right
AIEEE 2008 (1)
keyboard_arrow_right
AIEEE 2009 (2)
keyboard_arrow_right
AIEEE 2010 (1)
keyboard_arrow_right
AIEEE 2011 (1)
keyboard_arrow_right
AIEEE 2012 (1)
keyboard_arrow_right
JEE Main 2013 (Offline) (1)
keyboard_arrow_right
JEE Main 2014 (Offline) (1)
keyboard_arrow_right
JEE Main 2015 (Offline) (1)
keyboard_arrow_right
JEE Main 2016 (Offline) (2)
keyboard_arrow_right
JEE Main 2016 (Online) 9th April Morning Slot (1)
keyboard_arrow_right
JEE Main 2016 (Online) 10th April Morning Slot (1)
keyboard_arrow_right
JEE Main 2017 (Offline) (1)
keyboard_arrow_right
JEE Main 2017 (Online) 8th April Morning Slot (1)
keyboard_arrow_right
JEE Main 2017 (Online) 9th April Morning Slot (1)
keyboard_arrow_right
JEE Main 2018 (Offline) (2)
keyboard_arrow_right
JEE Main 2018 (Online) 15th April Morning Slot (1)
keyboard_arrow_right
JEE Main 2018 (Online) 15th April Evening Slot (1)
keyboard_arrow_right
JEE Main 2018 (Online) 16th April Morning Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 9th January Morning Slot (1)
keyboard_arrow_right
JEE Main 2019 (Online) 9th January Evening Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 10th January Morning Slot (3)
keyboard_arrow_right
JEE Main 2019 (Online) 11th January Morning Slot (1)
keyboard_arrow_right
JEE Main 2019 (Online) 12th January Evening Slot (1)
keyboard_arrow_right
JEE Main 2019 (Online) 8th April Morning Slot (1)
keyboard_arrow_right
JEE Main 2019 (Online) 8th April Evening Slot (1)
keyboard_arrow_right
JEE Main 2019 (Online) 9th April Morning Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 9th April Evening Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 10th April Morning Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 10th April Evening Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 12th April Morning Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 12th April Evening Slot (3)
keyboard_arrow_right
JEE Main 2020 (Online) 7th January Morning Slot (1)
keyboard_arrow_right
JEE Main 2020 (Online) 7th January Evening Slot (1)
keyboard_arrow_right
JEE Main 2020 (Online) 8th January Evening Slot (1)
keyboard_arrow_right
JEE Main 2020 (Online) 9th January Morning Slot (1)
keyboard_arrow_right
JEE Main 2020 (Online) 4th September Morning Slot (1)
keyboard_arrow_right
JEE Main 2020 (Online) 2nd September Morning Slot (1)
keyboard_arrow_right
JEE Main 2020 (Online) 3rd September Morning Slot (1)
keyboard_arrow_right
JEE Main 2020 (Online) 4th September Evening Slot (1)
keyboard_arrow_right
JEE Main 2020 (Online) 5th September Evening Slot (2)
keyboard_arrow_right
JEE Main 2020 (Online) 6th September Morning Slot (1)
keyboard_arrow_right
JEE Main 2021 (Online) 24th February Morning Slot (1)
keyboard_arrow_right
JEE Main 2021 (Online) 24th February Evening Slot (1)
keyboard_arrow_right
JEE Main 2021 (Online) 25th February Morning Slot (1)
keyboard_arrow_right
JEE Main 2021 (Online) 26th February Evening Shift (1)
keyboard_arrow_right
JEE Main 2021 (Online) 17th March Morning Shift (1)
keyboard_arrow_right
JEE Main 2021 (Online) 17th March Evening Shift (1)
keyboard_arrow_right
JEE Main 2021 (Online) 22th July Evening Shift (1)
keyboard_arrow_right

EXAM MAP

Joint Entrance Examination

JEE Advanced JEE Main

Graduate Aptitude Test in Engineering

GATE CE GATE ECE GATE ME GATE IN GATE EE GATE CSE GATE PI

Medical

NEET