PUC Science 2nd PUC Class 12 - Karnataka Board PUC Question Bank Solutions

Two light sources of intensities 8 cd and 12 cd are placed on the same side of a photometer screen at a distance of 40 cm from it. Where should a 80 cd source be placed to balance the illuminance?

The speed of sound in air is 332 m s⁻¹. Is it advisable to define the length 1 m as the distance travelled by sound in 1/332 s?

Consider Galileo's method of measuring the speed of light using two lanterns. To get an accuracy of about 10%, the time taken by the experimenter in closing or opening the shutter should be about one tenth of the time taken by the light in going from one experimenter to the other. Assume that it takes 1/100 second for an experimenter to close or open the shutter. How far should the two experimenters be to get a 10% accuracy? What are the difficulties in having this separation?

In Fizeau method of measuring the speed of light, the toothed wheel is placed in the focal plane of a converging lens. How would the experiment be affected if the wheel is slightly away from the focal plane?

In the original Fizeau method, the light travelled 8.6 km and then returned. What could be the difficulty if this distance is taken as 8.6 m?

What is the advantage of using a polygonal mirror with larger number of faces in Michelson method of measuring the speed of light?

Light passes through a closed cylindrical tube containing a gas. If the gas is gradually pumped out, the speed of light inside the tube will

The speeds of red light and yellow light are exactly same

An illuminated object is placed on the principal axis of a converging lens so that a real image is formed on the other side of the lens. If the object is shifted a little,

The speed of light is 299, 792, 458 ms⁻¹
(a) with respect to the earth
(b) with respect to the sun
(c) with respect to a train moving on the earth
(d) with respect to a spaceship going in outer space.

Which of the following methods can be used to measure the speed of light in laboratory?

Which of the following methods can be used to measure the speed of light in water?

In an experiment to measure the speed of light by Fizeau's apparatus, following data are used: Distance between the mirrors = 12.0 km,
Number of teeth in the wheel = 180.
Find the minimum angular speed of the wheel for which the image is not seen.

In an experiment with Foucault's apparatus, the various distances used are as follows:
Distance between the rotating and the fixed mirror = 16 m
Distance between the lens and the rotating mirror = 6 m,
Distance between the source and the lens = 2 m.
When the mirror is rotated at a speed of 356 revolutions per second, the image shifts by 0.7 mm. Calculate the speed of light from these data.

In a Michelson experiment for measuring speed of light, the distance travelled by light between two reflections from the rotating mirror is 4.8 km. The rotating mirror has a shape of a regular octagon. At what minimum angular speed of the mirror (other than zero) the image is formed at the position where a nonrotating mirror forms it?

Give an example of a life event which is likely to be stressful. Suggest reasons why it is likely to cause different degrees of stress to the person experiencing it.

Reflect on the environmental factors that have (a) a positive impact on the being, and (b) a negative effect.

Identify an aspect of your friend’s personal life that she/he wants to change. As a student of psychology, think of specific ways in which you can devise a programme to help your friend modify or solve her/his problem.

Describe the nature and scope of psychotherapy.

What do you understand by the term ‘environment’? Explain the different perspectives to understand the human-environment relationship.