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MCQ : Sound - 2


20 Questions MCQ Test Science & Technology for UPSC CSE | MCQ : Sound - 2


Description
This mock test of MCQ : Sound - 2 for Class 9 helps you for every Class 9 entrance exam. This contains 20 Multiple Choice Questions for Class 9 MCQ : Sound - 2 (mcq) to study with solutions a complete question bank. The solved questions answers in this MCQ : Sound - 2 quiz give you a good mix of easy questions and tough questions. Class 9 students definitely take this MCQ : Sound - 2 exercise for a better result in the exam. You can find other MCQ : Sound - 2 extra questions, long questions & short questions for Class 9 on EduRev as well by searching above.
QUESTION: 1

Speed of light or electromagnetic wave is higher than that of the speed of sound in air by

Solution:

Speed of light = 3* 108 m/s
Speed of sound = 3* 102 
Subtract  exponents to get the order. 
Therefore, 106  is the correct ✔ answer.

QUESTION: 2

Sound can travel through

Solution:
QUESTION: 3

Sonic booms are caused by the combination of

Solution:

The boom is the plane's sound waves combined together propagated at once. Air reacts like fluid to supersonic objects. As those objects travel through the air, molecules are pushed aside with great force and this forms a shock wave.

QUESTION: 4

Sound takes 2 seconds to travel 3 kilometres in water. What is the speed of sound in water?
Solution:

Here, distance = 3 km = 3000 m 
Time  = 2 sec 
Therefore, speed= distance / time
=  3000 /2
=  1500 m /s 

QUESTION: 5

Infrasonic fi Audible fa and Ultrasonic fu sounds are related a 
Solution:

Sound is only audible to the average humar ear if the frequencies lie between 20 Hz and 20 kHz. The actual range varies from person to person. Sound waves with frequencies less than 20 Hz are called infrasonic or subsonic and those with frequencies above 20 kHz are called ultrasonic. 

QUESTION: 6

Ultrasonic waves have frequencies
Solution:
QUESTION: 7

Which of the following is not the character of mechanical waves ?
Solution:
QUESTION: 8

Ultrasound is an application of
Solution:
QUESTION: 9

In the bell jar experiment, as air is removed
Solution:

The experiment is done by placing an electric bell in the bell jar. As the air is pumped out of the sealed bell jar, the sound from the bell jar fades. This demonstrates that the sound wave cannot travel through vacuum. That is, a sound wave needs a material medium for its propagation.

QUESTION: 10

Sound travels fastest in
Solution:
QUESTION: 11

Echo is not heard in a room of 10 m x 10 in x 10 m dimension due to (speed of sound in air = 300 m/s)
Solution:

If you have persistence, you continue to do something even though it is difficult or others are against it. 

( As the sensation of sound persists in our brain for about 0.1 s, to hear a distinct echo the time interval between  the original sound and the reflected one must be at least 0.1 s. If we take the speed of the sound to be 300 m/s at a given temperature, in air, sound must go to the obstacle and reach back the ear of the listener on reflection after 0.1s. )

QUESTION: 12

A key of a mechanical piano is struck gently and then struck again but much harder this time. In tine second case
Solution:
QUESTION: 13

The instruments Megaphone, Stethoscope, Hearing aids and Sound boards work based on the principle of
Solution:

Reflection of sound is used in many devices. For example ; megaphone, loudspeaker, bulb horn, stethoscope, hearing aid, sound board etc.

QUESTION: 14

In tlhe curve shown in figure half the wavelength is
Solution:
QUESTION: 15

A wave is moving with a speed of 3000 cm/s with reversal after every 0.01 second. The wavelength of the wave is
Solution:

The correct option is Option B.

Given:

T = 0.1 sec 

V = 3000 m/s

V = νλ = λ/T  ( as ν = 1/T )

3000 =  λ/0.1

 λ = 30 m

QUESTION: 16

Earthquake produces which kind of sound before the main shock begins?
Solution:
QUESTION: 17

Sonic booms are caused due to the variation of
Solution:
QUESTION: 18

Sound travels
Solution:

Sound  travels faster in soilds than in liquids, and faster in liquids than in gases. This is because the density of solids is higher than that of liquids which means that the particles are closer together.

QUESTION: 19

The minimum size of a room required to hear an echo of sound with a speed of 300 m/s is
Solution:

To hear a distinct echo the time interval between the original sound and the reflected one must be at least 0.15

QUESTION: 20

A thunder clap is heard 5.5 seconds after lightning flash. The distance of the flash is (Velocity of sound in air = 330 m/s)
Solution:

The speed is 330 m / s and the time taken is 5.5 second. Therefore, the distance would be speed * time ⇒ 5.5 * 330 = 1815m

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