A tuning fork A produces 4 beats/s with another tuning fork B of frequency 320 Hz. On filing one of the prongs of A, 4 beats/s are again heard when sounded with the same fork B. Then, the frequency of the fork A before filing is

• 328 Hz

• 316 Hz

• 324 Hz

• 320 Hz

Which one of the following statements is true?

• Both light and sound waves in air are transverse

• The sound waves in air are longitudinal while the light waves are transverse

• Both light and sound waves in air are longitudinal

• Both light and sound waves can travel in vacuum

A closed organ pipe of length 20 cm is sounded with tuning fork in resonance. What is frequency of tuning fork? (v = 332 m/s)

• 300 Hz

• 350 Hz

• 375 Hz

• 415 Hz

A transverse wave is expressed as, $\mathrm{y} = {\mathrm{y}}_{\mathrm{o}} \sin 2\mathrm{\pi f} \mathrm{t}$  For what value of λ, maximum particle velocity equals to 4 times the wave velocity?

• ${\mathrm{y}}_{\mathrm{o}} \frac{\mathrm{\pi }}{2}$

• $2 {\mathrm{y}}_{\mathrm{o}} \mathrm{\pi }$

• ${\mathrm{y}}_{\mathrm{o}} \mathrm{\pi }$

• ${\mathrm{y}}_{\mathrm{o}} \frac{\mathrm{\pi }}{4}$

When sound waves travel from air to water which one of the following remains constant?

• Time period

• Frequency

• Velocity

• Wavelength

The sound waves after being converted into electrical waves are not transmitted as such because

• they travel with the speed of sound

• the frequency is not constant

• they are heavily absorbed by the atmosphere

• the height of antenna has to be increased several times

An engine moving towards a wall with a velocity 50 m/s  emits a note of 1.2 kHz. Speed of sound in air is 350 m/s. The frequency of the note after reflection from the wall as heard by the driver of the engine is

• 2.4 kHz

• 0.24 kHz

• 1.6 KHz

• 1.2 kHz

168.

y = 3 sin $\mathrm{\pi } \left(\frac{\mathrm{t}}{2} - \frac{\mathrm{x}}{4}\right)$ represents an equation of a progressive wave, where t is in second and x is in metre. The distance travelled by the wave in 5 s is

• 8 m

• 10 m

• 5 m

• 32 m

A transverse wave is represented by the equation   $\mathrm{y} = {\mathrm{y}}_{\mathrm{o}} \sin \frac{2\mathrm{\pi }}{\mathrm{\lambda }} \left(\mathrm{vt} - \mathrm{k}\right)$.  For what value of $\mathrm{\lambda }$ is the particle velocity equal to two times the wave velocity 

• $\mathrm{\lambda } = \mathrm{\pi } {\mathrm{y}}_{\mathrm{o}}$

• $\mathrm{\lambda } = \frac{\mathrm{\pi } {\mathrm{y}}_{\mathrm{o}}}{2}$

• $\mathrm{\lambda } = \frac{\mathrm{\pi } {\mathrm{y}}_{\mathrm{o}}}{3}$

• $\mathrm{\lambda } = 2\mathrm{\pi } \mathrm{i} {\mathrm{y}}_{\mathrm{o}}$

When an open organ is dipped in water upto half of its height, then its frequency will become

• half

• double

• remain same

• four time