It seems a mysterious and even a magical force. That means, magnetism and electricity are so closely related to each other. The concept of this can be applied in many technologies for an effective productivity. Harmonic Motion and Waves Virtual Lab Harmonic Motion and Wave lab is the interdisciplinary science that deals with the study of sound, ultrasound and infrasound all mechanical waves in gases, liquids, and solids. The study of this lab revolves around the generation, propagation and reception of mechanical waves and vibrations.

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All precautions of sonometer experiment should be observed. The wire should be of soft iron or of any other magnetic material. Sources of error Wire may not be rigid and of uniform cross-sectional area.

Pulley may not be frictionless. Weights may not be correct. Knife edges bridges may not be sharp. The main frequency may not be stable. Alternative method To find the frequency of the A. Apparatus Same as in Experiment 8 except a separate horse shoe magnet and a separate step down transformer.

Theory A low alternating current passed directly through sonometer wire imposes forces on it the frequency v nu of the A. Let a loaded stretched soft iron wire have resonant length l1 for the main frequency. Let a tuning fork of frequency VT have resonant length l2. Diagram Procedure Steps 1 to 4 of Experiment Keeping the main switch off, connect the secondary of the step down transformer to the sonometer wire to pass a low voltage alternating current through it.

Put the main switch on. The current imposes its frequency on the soft iron wire. Take a horse shoe magnet and hold it over the middle of the wire AB with its NS line vertical. The wire will try to vibrate with the forced frequency of the current.

Since the long wire may have frequency less than that of the current, it may not vibrate. Steps 5 to 10 of Experiment Switch off the main and remove the transformer. Steps 11 to 13 of Experiment Table for frequency and length Same as in Experiment 10 except column 2 which records frequency of alternating current in place of frequency of electromagnet.

Percentage Error Same as in Experiment Precautions Same as in Experiment Viva Voce Question. What do you mean by A. Alternating current A. Direct current D. Steady current is the current whose magnitude and direction does not change with time. How does A. What is fluctuating current? A current having changing magnitude but not becoming zero and same direction, is called fluctuating current.

What is unidirectional current? A current having magnitude changing between maximum and zero and same direction, is called unidirectional current. How is A. What do you mean by one cycle of A. One cycle of A. Why is the instrument called a sonometer? Sono means sound. Therefore, a sonometer is an instrument which measures the frequency of sound. What is the unit of frequency of A. Unit of frequency of A. What is frequency of alternating current supplied to us in our houses?

The frequency is 50 hertz Hz [hertz means cycles per sec. Define root mean square or virtual or effective value of alternating current. It is that value of steady current which, when passed through a given resistor for certain time time of one complete cycle , shall produce the same quantity of heat as the given alternating current shall produce when passed through same resistor for same time.

What is resonance? When the natural frequency of a particle is equal to the frequency of driving force, then resonance takes place. The vibrations are called resonant vibrations. Give expression for r. For an alternating current having maximum peak value 70, Question.

Why does D. Main line carrying D. The person touching the line is repelled. Why does A. Main line carrying a. On touching it, the polarity of the body of the person also changes. Due to time lag, the body polarity remains opposite to that of the main line. The person touching the line is attracted. Why A. Give merits advantages of A. A 3-phase A.

Dynamo can produce more energy than a single phase D. Dynamo of same cost. Dynamo using slip rings has less loss of energy and wear and tear than a D. Dynamo using split ring commutator. Transmission of A. Give demerits disadvantages of A.

It increases effective resistance of the conductor. Commercial generators do not produce pure A. In certain applications like electroplating, battery charging, etc.

Only D. What is skin effect? It is found that in an alternating current, the tendency of the moving electrons is to drift towards the surface of the conductor while moving along its axis. This tendency increases with the frequency of A.

In very high frequency A. This phenomenon flow of electron on the surface of the conductor , is called skin effect. What is an electromagnet? A magnet magnetised by electric current, is called an electromagnet. Howls frequency of magnetisation of the electromagnet related with frequency of the alternating current which magnetises it?

It is twice the frequency of the alternating current. Why is frequency of magnetisation of electromagnet double of that of the alternating current? It is because the electromagnet is magnetised twice during one cycle of alternating current.

Which material is used to make sonometer wire? And Why? Because it is a ferromagnetic material. What is a timing fork? A timing fork is metallic bar bent into U-shape and having a heavy steps attached to the middle of the bent portion. What is function of a sounding board? When the vibrating tuning fork is placed on it, it is set into forced vibrations. Once the area of vibrating body increases the amplitude of vibration of the board wire system also increases.

What is the function of holes in the sonometer box? To make the inside air in communication with external air. What are natural vibrations? When a body is vibrating with its own natural way then it has natural vibrations. The frequency with which the body vibrate is, called its natural frequency.

What are forced vibrations? When a body is vibrating with frequency of driving force, other than its natural frequency then it has forced vibrations.


Sonometer Experiment



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