SECTION A- Is the speed of light in glass independent of the
colour of light? If not, which of the two colours; red
and violet, travels slower in a glass prism? - What would the diver see when looking up at the
water at angle of i > iC? - State the reason why microwaves are best suited for
long distance transmission of signals. - A converging lens is kept coaxially in contact with
a diverging lens, both lenses being of equal focal
lengths. What is the focal length of the combination? - Why can light waves be polarised while sound
waves cannot be polarised?
SECTION B - A convex lens of focal length 25 cm is placed coaxially
in contact with a concave lens of focal length 20 cm.
Determine the power of the combination. Will the
system be converging or diverging in nature? - Use the mirror equation to show that an object
placed between f and 2f of a concave mirror
produces a real image beyond 2f.
8. Which constituent radiation of the electromagnetic
spectrum is used
(a) in radar,
(b) to take photograph of internal parts of a human
body and
(c) for taking photographs of the sky during night
and foggy conditions?
Give one reason for your answer in each case.
9. Identify the electromagnetic waves whose
wavelengths vary as
(a) 10 –11 m < O < 10–14 m
(b) 10 –4 m < O < 10–6 m
Write one use of each.
10. Laser light of wavelength 630 nm incident on
a pair of slits produces an interference pattern
in which the bright fringes are separated by
7.2 mm. Calculate the wavelength of another source
of laser light which produces interference fringes
separated by 8.1 mm using same pair of slits.
11. (a) A ray of light falls on a transparent sphere with
centre C as shown in the gure. e ray emerges
from the sphere parallel to the line AB. Find the
CLASS XII
Electromagnetic Waves | Optics
Chapterwise practice questions for CBSE Exams as per the latest pattern and marking scheme
issued by CBSE for the academic session 2018-19.GENERAL INSTRUCTIONS
(i) All questions are compulsory. (ii) Q. no. 1 to 5 are very short answer questions and carry 1 mark each.
(iii) Q. no. 6 to 12 are short answer questions and carry 2 marks each. (iv) Q. no. 13 to 24 are also short answer questions and carry 3 marks each.
(v) Q. no. 25 to 27 are long answer questions and carry 5 marks each. (vi) Use log tables if necessary, use of calculator is not allowed.
Time Allowed : 3 hours Maximum Marks : 70