Waves

Question 1

Wave Motion

Answer 1

Kind of disturbance which travels through a medium due to repeated vibrations of the particles of the medium about their mean positions

Question 2

Propagation of Sound Waves through Air

Answer 2

• A small region in air is likes a spring - As it travell through the air, it compresses or expands it
• If a region is compressed, density increases of the second region causeing the first region density to decrease
• This causes rarefaction and hence shifts it to adjacent region

Question 3

Propagation of sound in a solid

Answer 3

• When an eleastic wave propagates, the atom is displaced from its equilibrium position and a restoring force is developed

Question 4

Transverse Waves

Answer 4

• Waves in which the individual particles of the medium oscillate perpendicular to the direction of wave propagation
• Travel through a liquid medium

Question 5

Longitudinal Waves

Answer 5

• Waves in which the individual particles of the medium oscillate along the direction of wave propagation
• Travel through all media

Question 6

Angular Frequency

Answer 6

Rate of change of phase with time

Question 7

Wavelength

Answer 7

Distance covered by a wave during the time in which a particle of the medium completes one vibration to and fro about its mean position

Question 8

Angular wave number / Propagation constant

Answer 8

Quantity 2pi / lambda (phase change per unit path difference)

Question 9

Wave velocity / Phase velocity

Answer 9

Direction covered by a wave per unit time in its direction of propagation

Question 10

Speed of transverse wave on stretched string

Answer 10

v = root (T / m)

Question 11

Speed of a transverse wave in a solid

Answer 11

v = root (modulus of rigidity (aka shear modulus) / ro)

Question 12

Speed of longitudinal Wave in a liquid or gas

Answer 12

v = root (k / ro)
k = bulk modulus

Question 13

Speed of longitudinal wave in a solid

Answer 13

root (k + 4/3 * shear modulus) / ro)

Question 14

Speed of a longitudinal wave in a solid rod

Answer 14

v = root (Y / ro)

Question 15

Newton’s Formula for speed of sound in a gas

Answer 15

v = root (P / ro)

Question 16

Laplace formula for speed of sound in a gas

Answer 16

v = root (gamma * P / ro)
gamma = Cp / Cv

Question 17

Plane Progressive harmonic wave

Answer 17

If during the propagation of a wave through a medium, the particles of the medium vibrate simple harmonically about their mean positions, then the wave is said to be plane progressive

Question 18

Factors which affect speed of sound in a gas

Answer 18

• Pressure has no effecet
• At constant pressure, v inversely proportional to square root of density
• Travels faster in moist air than dry hair
• Directly proportional to square root of abs. temp

Question 19

Progressive Wave

Answer 19

Wave that travels from one point of the medium to another