1431. A source of sound moves towards stationary observer with a speed of sound. If the frequency of sound from source is 100Hz, the apparent frequency of the sound heard by the observer is :

A. 75 Hz
B. 100 Hz
C. 150 Hz
D. None *

1432. Two sound waves having frequency 200 Hz and 250 Hz are travelling in air the speed of sound of 250 Hz is:

A. Greater than speed of 200 Hz
B. Less than speed of 200 Hz
C. Equal to speed of 200 Hz *
D. None

1433. An organ pipe of length ‘L’ has one end closed and other end open. The wavelength of fundamental note emitted is ?

A. Slightly smaller than 4 L
B. Slightly greater than 4 L *
C. Exactly equal to 3L/4
D. Slightly larger than 2 L

1434. Two progressive waves each of frequency 300 Hz are Superimposed to produce a stationary wave in which adjacent nodes are 1.5 m apart. the speed of wave is ?

A. 100 m/sec
B. 200 m/sec
C. 450 m/sec
D. 900 m/sec *

1435. Where in standing waves do the vibrations of medium occur?

A. Only at the nodes
B. Only at the antinodes
C. At every point between the antinodes and nodes *
D. At all the points between anti nodes

1436. The lower the frequency of wave :

A. The higher its velocity
B. The smaller its wavelength
C. The smaller its amplitude
D. The higher its period *

1437. An entirely longitudinal wave is :

A. A water wave
B. A sound wave *
C. An electromagnetic wave
D. A Wave in stretched string

1438. The wavelength of 400 Hz sound waves in air relative to the wavelength of 800Hz sound waves in air is :

A. Half as long
B. The same
C. Twice *
D. 4 times as long

1439. Waves whose crest are 30 m apart reaches to shore once every 3.0 sec. The wave velocity is ?

A. 0.1M/SEC
C. 10M/SEC *
D. 900M/SEC

1440. When light enter from air into glass, then which of the following will not change :

A. Wave lenght
B. Speed
C. Frequency *
D. Intensity