English

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.

Advertisements
Advertisements

Question

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.

Advertisements

Solution

(a) Puja displayed the values of great observation and curiosity to learn. Her father displayed the values of being a good father by considering her doubts serious and explaining them well to her.
(b) The phenomenon of light involved in the formation of coloured soap bubbles is interference of light on a thin film.

shaalaa.com
  Is there an error in this question or solution?
2013-2014 (March) Foreign Set 3

RELATED QUESTIONS

A solenoid of length 1.5 m and 4 cm in diameter possesses 10 turns per metre. A current of 5 A is flowing through it. The magnetic induction at a point inside the solenoid along the axis is ............................. .

0 = 4π × 10-7 Wb/Am)

  1. π  × 10-5 T
  2. 2π × 10-5 T
  3. 3π × 10-5 T
  4. 4π × 10-5 T

The device used for producing electric current is called _________.


Explain different ways to induce current in a coil.


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


Show diagrammatically how an alternating emf is generated by a loop of wire rotating in a magnetic field. Write the expression for the instantaneous value of the emf induced in the rotating loop.


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.


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.


Write the two names in the following diagram.

Fleming’s right hand rule.


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


A current I = 10 sin(100π t) A is passed in first coil, which induces a maximum e.m.f of 5π volt in second coil. The mutual inductance between the coils is ______.


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×