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महाराष्ट्र राज्य शिक्षण मंडळएचएससी विज्ञान (सामान्य) इयत्ता १२ वी

The energy stored in a 50 mH inductor carrying a current of 4 A is ______ - Physics

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प्रश्न

The energy stored in a 50 mH inductor carrying a current of 4 A is ______ 

पर्याय

  • 0.4 J

  • 0.1 J

  • 0.04 J

  • 0.01 J

MCQ
रिकाम्या जागा भरा
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उत्तर

The energy stored in a 50 mH inductor carrying a current of 4 A is 0.4 J.

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पाठ 12: Electromagnetic Induction - MCQ’S

व्हिडिओ ट्यूटोरियलVIEW ALL [1]

संबंधित प्रश्‍न

Electric field intensity in free space at a distance ‘r’ outside the charged conducting sphere of radius ‘R’ in terms of surface charge density ‘ a ’ is............................

(a)`sigma / in_0[R/r]^2`

(b)`in_0/sigma[R/r]^2`

(c)`R/r[sigma/in_0]^2`

(d)`R/sigma[r/in_0]^2`

 


The device used for producing electric current is called _________.


The magnetic flux through a loop is varying according to a relation `phi = 6t^2 + 7t + 1` where `phi` is in milliweber and t is in second. What is the e.m.f. induced in the loop at t = 2 second?


What is electromagnetic induction?


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


When an electric current is passed through any wire, a magnetic field is produced around it. Then why an electric iron connecting cable does not attract nearby iron objects when electric  current switched on through it?


 Name two devices in which electromagnets are used and two devices where permanent magnets are used.


 Explain why, the core of an electromagnet should be of soft iron and not of steel. 


 State the factors on which the strength of an electromagnet depends. How does it depend on these factors?


Write some of the important uses of electromagnets. 


The direction of current in the coil at one end of an electromagnet is clockwise. This end of the electromagnet will be:

(a) north pole
(b) east pole
(c) south pole
(d) west pole


The most suitable material for making the core of an electromagnet is:

(a) soft iron
(b) brass
(c) aluminium
(d) steel


What condition is necessary for the production of current by electromagnetic induction?


 What do you understand by the term "electromagnetic induction"? Explain with the help of a diagram. 


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


When the magnet shown in the diagram below is moving towards the coil, the galvanometer gives a reading to the right. 

 

() What is the name of the effect being produced by the moving magnet?
(2) State what happens to the reading shown on the galvanometer when the magnet is moving away from the coil.
(3) The original experiment is repeated. This time the magnet is moved towards the coil at a great speed. State two changes you would notice in the reading on the galvanometer.


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 .


Welders wear special glass goggles while working. Why? Explain.


When Puja, a student of 10th class, watched her mother washing clothes in the open, she observed coloured soap bubbles and was curious to know why the soap bubbles appear coloured. In the evening when her father, an engineer by profession, came home, she asked him this question. Her father explained to her the basic phenomenon of physics due to which the soap bubbles appear coloured.
(a) What according to you are the values displayed by Puja and her father?
(b) State the phenomenon of light involved in the formation of coloured soap bubbles.


A conducting square loop of side l and resistance R moves in its plane with a uniform velocity v perpendicular to one of its sides. A uniform and constant magnetic field Bexists along the perpendicular to the plane of the loop as shown in figure. The current induced in the loop is _____________ .


A conducting rod is moved with a constant velocity v in a magnetic field. A potential difference appears across the two ends _____________ .


L, C and R represent the physical quantities inductance, capacitance and resistance respectively. Which of the following combinations have dimensions of frequency?

(a) `1/(RC)`

(b) `R/L`

(c) `1/sqrt(LC)`

(d) C/L


The switches in figure (a) and (b) are closed at t = 0 and reopened after a long time at t = t0.

(a) The charge on C just after t = 0 is εC.
(b) The charge on C long after t = 0 is εC.
(c) The current in L just before t = t0 is ε/R.
(d) The current in L long after t = t0 is ε/R.


Calculate the dimensions of (a) \[\int \overrightarrow{E} . d \overrightarrow{l,}\] (b) vBl and (c) \[\frac{d \Phi_B}{dt}.\] The symbols have their usual meaning.


Figure shows a wire sliding on two parallel, conducting rails placed at a separation l. A magnetic field B exists in a direction perpendicular to the plane of the rails. What force is necessary to keep the wire moving at a constant velocity v?


Draw a simple labeled diagram of a step-up transformer.


The diagram 10 shows two coils X and Y. The coil X is connected to a battery S and a key K. The coil Y is connected to a galvanometer G.

When the key K is closed. State the polarity
(i)At the end of the coil X,
(ii)At the end C of the coil Y,
(iii)At the end C of the coil Y if the coil Y is (a) Moved towards the coil X, (b) Moved away from the coil X.


Draw and label the diagram of a simple D.C. motor.
(a) Explain the rotation of the coil, giving a reason for your answer.
(b) How can you reverse the direction of rotation of the armature?
(c) How can you increase the speed of rotation of the motor?


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.


Complete the following diagram of a transformer and name the parts labeled A and B. Name the part you have drawn to complete the diagram . What is the material of this part? In this transformer a step-up or step-down? Why?


State the purpose of soft iron core used in making an electromagnet.


Draw a labelled diagram to make an electromagnet from a soft iron bar. Mark the polarity at its ends in your diagram. What precaution would you observe while making it?


The diagram shows a rectangular coil ABCD, suspended freely between the concave pole pieces of a permanent horseshoe magnet, such that the plane of the coil is parallel to the magnetic field.

  1. State your observation when the current is switched on.
  2. Give an explanation for your observation in (i).
  3. State the rule, which will help you to find the motion of rotation of the coil.
  4. In which position will the coil ultimately come to rest?
  5. State four ways of increasing the magnitude of force acting on the coil.

State Lenz’s law.


A closely wound circular coil of radius 0.02 m is placed perpendicular to the magnetic field. When the magnetic field is changed from 8000 T to 2000 T in 6 s, an emf of 44 V is induced in it. Calculate the number of turns in the coil.


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.


Metal rings P and Q are lying in the same plane, where current I is increasing steadily. The induced current in metal rings is shown correctly in figure.


The laws of electromagnetic induction have been used in the construction of a ______.

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

The instrument that use to defect electric current in the circuit is known as ____________.


We can induce the current in a coil by ____________.


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?


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.

Consider the situation where the Magnet goes in and out of the coil. State two changes which could be made to increase the deflection in the galvanometer.


If the sun radiates energy at the rate of 3.6 × 1033 ergs/sec the rate at which the sun is loosing mass is given by ______.


Which of the following instruments works by electromagnetic induction?


For making a strong electromagnet the material of the core should be ______.


A coil of one turn is made of a wire of certain length and then from the same length, a coil of two turns is made. If the same current is passed in both the cases, then the ratio of the magnetic inductions at their centres will be:


The working of a dynamo is based on the principle of


A rectangular, a square, a circular and an elliptical loop, all in the (x - y) plane, are moving out of a uniform magnetic field with a constant velocity `vecv = vhati`. The magnetic field is directed along the negative z-axis direction. The induced emf, during the passage of these loops, out of the field region, will not remain constant for ______.


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.)


The charge will flow through a galvanometer of resistance 200Ω connected to a 400Ω circular coil of 1000 turns wound on a wooden stick 20 mm in diameter, if a magnetic field B = 0.012 T parallel to the axis of the stick decreased suddenly to zero, is near ______.


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