Infrasonic : less than 20Hz (can not be heard by humans) Ultrasonic : between 20Hz and 20kHz (can be heard by humans) Supersonic : more than 20kHz (can not be heard by humans)
41) Sound of frequency below 20 Hz is called
Answer is:
infrasonic
Explanation:
Related General Physics MCQ with Answers
Answer is:
cohesion of mercury is greater than its adhesion with glass
Explanation:
Cohesion is nothing but attraction between two atoms.
Answer is:
increase its electrical conductivity
Explanation:
This principle is known as Doping. Adding of an impurity to a pure semi conductor in order to increase certain properties.
Answer is:
the refractive index of the different layers of the earth's atmosphere changes continuously, consequently the position of the image of a start changes with time
Explanation:
The scientific name for the twinkling of stars is stellar scintillation (or astronomical scintillation). Stars twinkle when we see them from the Earth's surface because we are viewing them through thick layers of turbulent (moving) air in the Earth's atmosphere.
Answer is:
in the hills the atmospheric pressure is lower than that in the plains and therefore water boils at a temperature lower than 100oC causing an increase in cooking time
Explanation:
I would like to give you an example "Pressure Cooker". The pressure level inside the Cooker is increased to 15 PSI(Pounds per square inch). So the rise is cooked at the temperature 120 degree Celsius. Therefore, the rise is cooked in 15 minutes. If you cook the rise in an open vessel, it will take up to 30 minutes to cook the rise. Because the rise is cooked in 100 degree Celsius (because of the normal atmosphere which is less than that inside the Pressure cooker). That's why it takes much time to cook. Similarly, in the hills the atmospheric pressure is lower than that in the plains and therefore water boils at a temperature lower than 100 degree Celsius causing an increase in cooking time.