What is the range of human hearing?

• 20 Hz - 2 kHz

• 20 Hz - 20 kHz

• 2 Hz - 20 kHz

• 2 kHz - 20 kHz

Sound of frequency less than 20hz is called ____ .

• Ultrasound

• Infrasonic sound

• Ultrasonic sound

• None of these

SONAR stands for ____ .

• Song Navigation and Ranging

• Sound Navigation and Rare

• Sound Navigation and Ranging

• Sound Nitrogen and Rearing

Sound frequency more than 20kHz is called ____ .

• Infrasound

• Ultrasound

• Infrasonic Sound

• All of these

Rhinoceros, whales and elephants produce which type of sound to communicate?

• Ultrasound

• Infrasonic sound

• Infrasound

• Ultrasonic sound

Dolphins, bats ,rats and porpoises use ____ sounds to communicate.

• Ultrasound

• Infrasound

• Infrasonic sound

• Ultrasonic sound

Hearing aid is used by people who ____ .

• Have broken legs

• Are blind

• Have poor eyesight

• Hearing loss

Ultrasonic waves reflect form the parts of the heart forming its image is called ____.

• Ultrasonography

• Echocardiography

• Cardiology

• Physiotherapy

SONAR is installed in ____.

• Ear

• Ships and Boat

• Airplanes

• Fishes

A boy shouts standing in front of a hill which is at a distance of 6m from him. He hears an echo after 3 sec. Find the speed of the sound. [use 2d=v×t]

• 4m/sec

• 5m/sec

• 12m/sec

• 6m/sec

Answer explanation

given:

d=6m

t=3 sec

using 2d=vt

⇒ 2×6=v×3

⇒ v = 12/3

= 4m/sec (a)