#### • Class 11 Physics Demo

Explore Related Concepts

#### • electromagnetic waves and wave optics

Question:......at room temperature is associated with this frequency? (Assume the speed of sound to be 340 m/s.) Can somebody show me the setup? Thanks.

Answers:The wave equation c = x f hold also for the sound, where c is the speed of sound, f is the frequency and is the wavelength. So, = c / f = 340 m/s / 20,000 /s = 0.017 m = 17 mm.

Question:what do they detect and how? how come they can still detect you in the boot of a car?

Answers:They consist of a transmitter (loudspeaker) and a receiver (microphone) The ultrasonic range is used so the constant noise doesn't annoy people (I have no idea what it might do for dogs and bats!) the transmitter sets up a very stable standing wave of high frequency sound which is picked up by the receiver. If anything gets between these two devices, the frequency changes a bit. This change is detected by the receiver and the alarm triggered. It can be very sensitive and so will detect movement in the boot but not all are as good as that and only work in the passenger compartment.

Question:What is the wavelength of a 340-Hz tone in air? What is the wavelength of a 34,000-Hz ultrasonic wave in air? Help please. Thanks so much!

Answers:340 Hz = 1 meter 34,000 Hz = 1 millimeter

Question:i did the tuning fork math experiment where you get the vibrations of a tuning fork on your calculator, and i need to relate the lab to a concept or application of mathatics in the real world

Answers:The obvious application is using a tuning fork to tune an instrument to a particular note/key.