English
Maharashtra State BoardSSC (English Medium) 10th Standard

Answer the Following: State the Principles of the Electric Motor and Electric Generator. - Science and Technology 1

Advertisements
Advertisements

Question

Answer the following:

State the principles of the electric motor and electric generator. 

Short/Brief Note
Advertisements

Solution

  1. Principle of electric motor:
    Electric motor works on the principle that a current carrying conductor placed in a magnetic field experiences a force.
  2. Principle of electric generator:
    Electric generator works on the principle of electromagnetic induction. When the coil of electric generator rotates in a magnetic field. The magnetic field induces a current in this coil. This induced current then flows into circuit connected to the coil.
shaalaa.com
  Is there an error in this question or solution?
2013-2014 (October)

APPEARS IN

RELATED QUESTIONS

The device used for producing electric current is called _________.


A metal rod `1/sqrtpi `m long rotates about one of its ends perpendicular to a plane whose magnetic induction is 4 x 10-3 T. Calculate the number of revolutions made by the rod per second if the e.m.f. induced between the ends of the rod is 16 mV.


Explain different ways to induce current in a coil.


Prove theoretically  (electromagnetic induction) `e = (dphi)/(dt)`


State three ways in which the strength of an electromagnet can be increased.


Write some of the important uses of electromagnets. 


 Name one device which works on the phenomenon of electromagnetic induction. 


How is the working of an electric bell affected, if alternating current be used instead of direct current?


In which of the following case does the electromagnetic induction occur?
The current is stopped in a wire held near a loop of wire .


A light metal disc on the top of an electromagnet is thrown up as the current is switched on. Why? Give reason.


Can you find the magnitude of current using Fleming's right hand rule?

Fig. shows a simple form of an A.C. generator.

(a) Name the parts labeled A and B.
(b) What would be the effect of doubling the number of turns on the coil if the speed of rotation remains unchanged?
(c) Which of the output terminals is positive if the coil is rotating in the
direction shown in the diagram (anticlockwise)?
( d ) What is the position of the rotating coil when p.d. across its ends is zero? Explain why p.d. is zero when the coil is at this position .
(e) Sketch a graph showing how the p.d. across the ends of the rotating coil varies with time for an A.C. dynamo.
( f) On th e same sheet of paper and vertically below the first graph using the same time scale, sketch graphs to show the effect of
(i) Doubling the speed of rotation and at the same time keeping
the field and the number of turns constant,
(ii ) Doubling the number of turns on the coil and at the same time
doubling the speed of rotation of the coil, keeping th e speed
constant.


Why do you mean by turns ratio of a transformer? Can it work with D.C.?

Name the following diagram and explain the concept behind it.


List two ways of increasing the strength of an electromagnet if the material of the electromagnet is fixed.


Why soft iron is preferred to be used as the core of the electromagnet of an electric bell?


You have been provided with a solenoid AB.

(i) What is the polarity at end A?
(ii) Give one advantage of an electromagnet over a permanent magnet.


State the condition at which we say the two coils kept close to each other are perfectly coupled with each other. 


Using Ampere's law, obtain an expression for the magnetic induction near a current-carrying straight infinitely long wire. 


Fleming's left hand rule : electric current : : Fleming's right hand rule : _______


Write the two names in the following diagram.

Right hand thumb rule.


What for an inductor is used? Give some examples.


Give an illustration of determining direction of induced current by using Lenz’s law.


A straight metal wire crosses a magnetic field of flux 4 mWb in a time 0.4 s. Find the magnitude of the emf induced in the wire.


Using Lenz’s law, predict the direction of induced current in conducting rings 1 and 2 when the current in the wire is steadily decreasing.


An alternating emf of 0.2 V is applied across an L-C-R series circuit having R = 4Q, C = 80µF, and L = 200 mH. At resonance the voltage drop across the inductor is


In electromagnetic induction, the induced charge is independent of ______.

For magnetic breaking in trains, strong electromagnets are situated above the rails in some electrically powered trains. When the electromagnets are activated, the ...A... induced in the rails oppose the motion of the train. As there are no ... B... linkages, the ...C... effects is smooth. Here, A, B and C refer to ______.

Ansari Sir was demonstrating an experiment in his class with the setup as shown in the figure below.

A magnet is attached to a spring. The magnet can go in and out of the stationary coil. He lifted the Magnet and released it to make it oscillate through the coil.
Based on your understanding of the phenomenon, answer the following question.

What is the principle which Ansari Sir is trying to demonstrate?


Name some equipment that uses electromagnetism for functioning.


Induced current flows through a coil ______.


Sea turtles return to their birth beach many decades after they were born due to ______.


The working of a dynamo is based on the principle of


In the given circuit, initially switch S1 is closed and S2 and S3 are open. After charging of capacitor, at t = 0, S1 is open and S2 and S3 are closed. If the relation between inductance capacitance and resistance is L = 4CR2 then the time (in sec) after which current passing through capacitor and inductor will be same is ______ × 10-4 N. (Given R = ℓn(2), L = 2mH)


One solenoid is centered inside another. The outer one has a length of 50.0 cm and contains 6750 coils, while the coaxial inner solenoid is 3.0 cm long and π cm2 in area and contains 150 coils. The current in the outer solenoid is changing at 3000 A/s. The emf induced in the inner solenoid is ______ V.

(Round off to two decimal places.)


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×