BEATS

DEFINITION: -

"Beats can be defined as the periodic variation in the intensity of sound at a given point

due to super-position of two waves having slightly different frequencies."

EXPLANATION: - 

When two waves having slight difference of frequency and same amplitude pass through the same region of space, interference takes place. This type of interference is known as 'Beats'. In this case when two waves are observed at a given point they are periodically in or not of step with one another. That is, there is an alternation in time b/w constructive and destructive interference. This alternation is called Beats

EXPLANATION WITH EXAMPLE: -

If two tuning forks of slightly different frequencies are set to vibrate simultaneously, we hear a sound of alternating high and low intensity. This is called a beat and phenomenon is called is Beats.

BEAT FREQUENCY: -

Beat frequency is the no. Of beats one hears in one second. It is defined as the difference infrequency b/w two sounds.

The maximum beat frequency that a human ear can detect is 7beats/seconds.

ULTRASONICS: -

Definition: -

The longitudinal waves with frequencies above the audible range are known as ULTRASONICS. Ultrasonic have frequency greater than 20,000Hz.

PRODUCTION OF ULTRASONICS: -

Ultrasonic are produced by vibrating quartz crystals electricity. With the help of this device very high frequency range ultrasonic waves can easily be produced.

USES OF ULTRASONICS IN MEDICINE: -

·         Ultrasonic is now widely used as diagnostic therapeutic and surgical tool in medicine.

·         Ultrasonic is preferred over x-rays due to safety.

·         To kill microbes in liquids.

IN INDUSTRY: -

·         To find cracks in metal structures.

IN TECHNOLOGY: -

·         They are used in echo-depth sounding devices for determining depth of sea.

·         In under water navigation ultrasonic is used instead of RADAR.

IN GENERAL: -

·         In guidance devices for blind persons.

SECOND'S PENDULUM: -

A pendulum that completes its one vibration is two seconds is known as 2nd’s pendulum.

Or

A pendulum whose time period is 2 sec is called second's pendulum.

·         Frequency of second pendulum is 0.5Hz

·         Length of second's pendulum is 100cm.