ST.

ANTHONY’S SCHOOL (GIRLS’)

Section - I (40 marks)

a) A crane 'A' lifts a heavy load in 5 seconds whereas another crane B does the same work in 2 seconds.
Compare the power of crane A to that of crane B. (2)

b) A ray of light falls normally on a rectangular glass slab. Draw a ray diagram showing the path of ray till
it emerges out of the slab. (2)

c) Complete the path of monochromatic light ray AB incident on the surface PQ of the equilateral glass
prism PQR till it emerges out of the prism due to refraction.(2)

d) Where should an object be placed in front of a convex lens in order to get

i) an enlarged real image.

ii) an enlarged virtual image.

e) A pond appears to be 2.7 m deep. If refractive index of water is 4/3. Find the actual depth of the
pond. (2)

Question 2.

a) An electromagnetic radiation is used for photography in fog.(2)

i) Identify the radiation.

b) i) Define couple.

ii) State the SI unit of moment of couple.

c) i) State and define the SI unit of power.

ii) How is the unit horsepower related to the SI unit of power.

d) A half metre rod is pivoted at the centre with two weights of 20 gf and 12 gf suspended at a
perpendicular distance of 6 cm and 10 cm from the pivot respectively as shown below:- (3)

e) Give one use of ultraviolet radiation. (1)

Question 3

a) A lens forms an upright and diminished image of an object when the object is placed at the focal point
of the given lens (3).

i) Name the lens.

ii) Draw a ray diagram to show the image formation.

b) With reference to the terms M.A, VR and efficiency of a machine name and define the term that will
not change for a machine of a given design. (2)

c) i) Copy the diagram given below and complete the path of light ray till it emerges out of the prism.
The critical angle of glass is 42⁰. In your diagram mark the angles whereever necessary. (3)
ii) State the dependence of angle of deviation

i) on refractive index of the material of the prism.

ii) on the wavelength of light. (2)

Question 4.

a) State the energy changes in the following devices while in use:

i) A loud speaker

ii)A glowing electric bulb. (2)

b) Define dispersion. (2)

c) i) Define the power of a lens.(2)

ii) The focal length of a convex lens is 25 cm. Express its power with sign. (2)

d)i) In what way does an ideal machine differ from a practical machine?

ii) Can a simple machine act as a force multiplier and speed multiplier at the same time?(2)

Section II (40 marks)

a) A ball of mass 200 g falls from a height of 5 m. What will be its kinetic energy when it just reaches the
ground? (g = 9.8 m/s²). (3)

b) What is lateral displacement? Draw a ray diagram showing the lateral displacement of a ray of light
when it passes through a parallel sided glass slab. (3)

c) i) When does the ray of light falling on lens pass through it undeviated?

ii) Which lens can produce a real and inverted image of an object?(2)

d) Name the electromagnetic spectrum in increasing order of their wavelength.(2)

Question 6.

a)i) What is meant by the term critical angle?

ii) How is it related to the refractive index of the medium?

iii) Does the depth of a tank of a water appear to change or remain the same when viewed normally
from above? (3)
b) A ray of light PQ is incident normally on the hypotenuse of a right angled prism ABC as shown in the
diagram given below

i) Copy the diagram and complete the path of the ray PQ till it emerges from the prism.

ii) What is the value of the angle of deviation of the ray?

iii) Name an instrument where this action of prism is used. (3)

c) A converging lens is used to obtain an image of an object placed in front of it The inverted image is
formed between F2 and 2 F2 of the lens.

i) Where is the object placed?

ii) Draw a ray diagram to illustrate the formation of image obtained.

Question 7

a) A block and tackle system of pulleys has a V.R 4.

i) Draw a labelled diagram of the system indicating clearly the points of application and directions of
load and effort.

ii) What is the value of the M A of the given pulley system if it is an ideal pulley system. (4)

b) i) When does a force do work ?

ii) A nut is opened by a wrench of length 20 cm . If the least force required is 2 N. Find the moment of
force needed to loosen the nut.

iii) Explain briefly why the work done by a fielder when he takes a catch in a cricket match is negative(4)
c) Rohan exerts a pull of 150 kgf. What is the maximum load he can raise with the pulley system if its
efficiency is 75%? (2)

Question 8.

a) A diver in water looks obviously at an object AB in air. (3)

i) Does the object appear taller, shorter or of the same size to the diver?

ii) Show the path of two rays AC and AD starting from the tip of the object as it travels towards the
diver in water and hence obtain the image of the object.

b) Complete the path of the ray AB through the glass prism in PQR till it emerges out of the prism. Given
the critical angle of glass as 42°. (3)

c)A lens of focal length 20 cm forms an inverted image at the distance 60 cm from the lens. (4)

i)Identify the lens.

ii) How far is the lens present in front of the object?

iii) Calculate the magnification of the image.

a) Define centre of gravity. Can the centre of gravity of a body be situated outside its material? Give an
example(3)

b) How does the angle of deviation formed by a prism change with the increase in the angle of
incidence?Draw a graph showing the variation in the angle of deviation with the angle of incidence at a
prism surface. (3)

c) i) Draw a diagram to show a block and tackle pulley system having a velocity ratio of 3 marking the
direction of load L, effort E and tension T.

ii) The pulley system drawn lifts a load of 150 N when an effort of 60 N is applied. Find its mechanical
advantage.

iii) Is the above pulley system an ideal machine or not ? (4)

Question 10.

a) Define spectrum. What is the cause of formation of spectrum? (3)

b) State the conditions required for total internal reflection of light to take place.(2)

c) A boy weighing 40 kgf climbs up a stairs of 30 steps each 20 cm high in 4 minutes and a girl weighing
30 kgf does the same in 3 minutes. Compare i) the work done by them and ii)the power developed by
them. (3)

d) A pendulum is oscillating on either side of its rest position. What are the energy changes that take
place in the oscillating pendulum? (2)