JEE Advanced paper is considered to be one of the toughest entrance exams in India. Moreover, this Physics is considered the toughest subject because it is the most application-based. The student needs to get the basics right and then move on to mastering advanced concepts. Waves consist of nearly about 4-5 % of marks in the Physics section.

**Q1. The frequency of a sonometer wire is 10 Hz. When the weights producing the tension are completely immersed in water the frequency becomes 80 Hz and on immersing the weights in a certain liquid the frequency becomes 60 Hz. The specific gravity of the liquid is**

**Q2. The mathematical form of three travelling waves is given by**

Y

Y

And Y

of these waves

Y

_{1}= (2 cm) sin(3x-6t)Y

_{2}= (3 cm) sin(4x-12t)And Y

_{3}= (4 cm) sin(5x-11t)of these waves

Solution

(d)

For the wave, y=A sin (kx - Ï‰t), the wave speed is Ï‰ / k and the maximum transverse string is A Ï‰

(d)

For the wave, y=A sin (kx - Ï‰t), the wave speed is Ï‰ / k and the maximum transverse string is A Ï‰

**Q4. A closed organ pipe and an open organ pipe of same length produce 2 beats when they are set into vibration simultaneously in their fundamental mode. The length of the open organ pipe is now halved and of the closed organ pipe is doubled; the number of beats produced will be**

**Q5. The amplitude of a wave disturbance propagating along positive X-axis is given by y = 1 / ( 1 + x**

^{2}) at t=0 and y = 1 / [ 1 + (x-2)^{2}] at t = 4 s where x and y are in metre. The shape of wave disturbance does not change with time. The velocity of the wave is**Q7. An air column closed at one end and opened at the other end, resonates with a tuning fork of frequency v when its length is 45 cm and 99 cm and at two other lengths in between these values. The wavelength of sound in air column is**

**Q8. Two waves having intensity I and 9I produce interference. If the resultant intensity at a point is 7I, what is the phase difference between the two waves?**

**Q9. A siren placed at a railway platform is emitting sound of frequency 5 kHz. A passenger sitting in a moving train A records a frequency of 5.5 kHz while the train approaches the siren. During his return journey in a different train B he records a frequency of 6.0 kHz while approaching the same siren. The ratio of velocity of train B to that of train A is**

**Q10. A closed organ pipe has length ‘l’. The air in it is vibrating in 3rd overtone with maximum amplitude ‘a’. The amplitude at a distance of l/7 from closed end of the pipe is equal to**