Paper Physics Class 10th 2014-15

Paper: Physics                Class:10^th    Name:                                     Section:     

Date:                              Total Marks: 25                       Obtained Marks:

Q.1 Tick the correct answer.

i)The study of sound is called.

a) Reflection         b) SONAR   c) Acoustics d) None

ii) Value of reference intensity is

a) 3 x 103wm^-2      b) 10-12wm^-2       c) 20 hz       d) 20000 hz

iii) 1 bell is equal to

a) 20 dB      b) 10^-3 dB    c) 10^-12 dB   d) 10dB

iv) How does sound travel from its source to your ear?

a) by change in air pressure    b) by infrared waves

c) by electromagnetic wave      d) none

v) Find frequency of sound when speed of sound is340ms^-1 and wavelength 0.5

a) 720 hz     b) 680 hz    c) 650 hz     d) 550 hz

Q.2 Attempt any six questions.

i) Is there any difference between echo and reflection of sound?

ii) Discuss audible frequency range            iii) Define pitch and quality

iv) Define intensity of sound and give its unit

v) What factors on which frequency of tunning fork depends

vi) Why ultrasound is useful in medical field

vii) A doctor counts 72 heartbeats in 1 min.Calculate the frequency and period of heartbeat.

viii) How we can find the depth of a sea?

Q.3 Attempt any two questions.

a) Discuss intensity level

b) What are the factors on which loudness of a sound depends. discuss one by one

c) The highest frequency sound humans can hear is about 20,000 hz .What is the wavelength of sound in air at this frequency at a temperature of 20⁰C? What is the wavelength of the lowest sound we can hear of about 20 hz . Assume the speed of sound in air at 20⁰C is 343ms^-1.