The echo (reflected sounD. will be distinctly heard only at ordinary temperatures if the distance of the reflecting surfaces from the source of sound is at least ________?

Related Mcqs:

1. Echo is a ___________ of sound?

   A. Reflection
   B. Refraction
   C. Interference
   D. None

   Submitted by: Awais

2. The cracking sound heard when dry hair is combed with a hard rubber comb is due to_________?

   A. The hair barging against the charged comb
   B. Small electric sparks
   C. The rubbing of the comb with the hair
   D. None of the above

3. What inspired reflecting road lights to be invented?

   A. Car door reflecting mirrors
   B. The light a cat’s eyes gave off on a fence
   C. Sun light on steel posts on road sides
   D. The sun light on the windshield

   Submitted by: Rashid Mehmood

4. Name the branch of science which deals with the study of sound and sound waves?

   A. Aeronautics
   B. Acoustics
   C. Aerostatics
   D. Aetiology

   Submitted by: ABDUL HAYEE

5. Which of the following principleis used to produce ‘low-temperatures’ ?

   A. Super conductivity
   B. Joule-Kelvin effect
   C. Thermo-electric effect
   D. Adiabatic demagneti-sation

   Submitted by: Malik Asghar Hussain

6. The extremely cold temperatures in the polar region of moon mean that it can act as a kind of __________ where things do not undergo much change.

   A. Time capsule
   B. Light capsule
   C. Meta capsule
   D. Natural capsule

   Submitted by: Muhammad Abdullah

7. An ordinary mobile phone communicate by using___________?

   A. Sound waves
   B. Infrared waves
   C. UV waves
   D. Radio waves

   Submitted by: Farhan Rana

8. Medium which sends signal from source to destination is known as ________ ?

   A. Transmitter
   B. Transmission channel
   C. Receiver
   D. Hardware

   Submitted by: Rashid Mehmood

9. The Distance of Neptune From Sun is ________ astronomical unit.

   A. 28
   B. 30
   C. 32
   D. None of these

   Submitted by: ABU HURAIRA RAI

10. What is the distance of the star Proxima Centauri from the planet Earth ________?

    A. 4.2 light years
    B. 3.2 light years
    C. 2.4 light years
    D. 1.5 light years

    Submitted by: Adeeb Rahman