Narsee Monjee Educational Trust's

JAMNABAI NARSEE SCHOOL 9 contactus@jns.ac.in

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Vile Parle (W), Mumbai - 400 049, India. www.jns.ac.in

SECOND PRELIMINARY EXAMINATION JANUARY 2025

PHYSICS
Std.10
Time: 2 hrs.
Marks: 80
Date: 02.01.2025

Answers to this paper must be written onthe paper providedseparately.

You will not be allowed to write during the first 15 minutes.
This time is to be spent in reading the question paper.
The time given at the head of this Paper is the time allowed for writing the answers.

Section Ais compulsory. Attempt any four questions from Section B

The intended marks for questions or parts of questions are given in brackets [].

This paper consists of 12 printed pages.

SECTION A
(Atempt all questions from this Section.)
Question 1 -[15]
Choose the correct answers to the questions from the given options.
(i) A boy draws water from a well using a fixed pulley.

The work done by boy is

(a) positive
(b) negative
(c) zero work done
(d) none of these
(ii) Alfiyaa holds a bucket by applying a 10 N force. She then moves a horizontal distance of
5m and climbs upa vertical distance of 10 m. What is the total work done by Alfiyaa?
(a) 50J
(b) 100J
(c) 150J
(d) 200J
 (iü) Rachacl took a thick glass slab whose one opposite parallel face is
that it formed multiple images. This happened on silvered. She observed
(a) refraction of light accountof
(b) reflection of light
(c) dispersion of light
(d) both (a) and (b)
(iv) When a nucleus in an atom undergoes a
levels of the atom radioactive decay, then the electronic energy
(a) change for a-radioactivity, but not for others
(b) change for ß-radioactivity, but not for others
(c) change for a and B-radioactivity, but not for y
(d) do not change for any type of radioactivity -radioactivity
(v) The spectrum (VIBGYOR) of white light can be laterally displaced 0°
using which of the following arrangements? with deviation
(a) Asingle prism with a light ray refracted parallel to its base.
(b) Two prisms of the same refractive index, placed adjacent to each
(c) Two prisms of the same refractive index, placed inverted other.
(d) Three prisms placed alternately.
relative to each other.

(vi) In Apurva's system, there are four media labelled A, B,

Cand D with refractive indices i 145, u1.5,
s =1.55 and 145, respectively. Avisiblelight ray
enters from medium Aand emerges parallel to its initial
direction, as illustrated in the figure.
Which medium has the highest frequency for the visible
light ray?
(a) Medium A
(b) Medium C
(c) Medium A and D
(d) Medium A, B, C&D

(vii) The diagram alongside shows a force F=5N acting at point A

produces a moment of force of 6 Nm about point O. What is the
diameter of the wheel?
(a) 1.2 m
(b) 2.4 m
(c) 3.4 m
(d) 3.6 m

(vii) Assertion (A): The efficiency of machine decreases when there is an energy loss due to
friction and other factors.
Reason(R): Efficiency is the ratio of usefulwork output to the total work input including
loss.
(a) Both Aand Rare true and Ris the correct explanation of A.
(b) Both Aand Rare true andR is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but the R is true.
2
(ix) Anew cell is marked 1.5 V when connected to an external resistance, the
voltmeter
connected to its terminal reads I.25 V. The drop in potentialacross the terminals of the
cell is due to the
(a) internal resistance of the cell
(b) external resistance
(c) equivalent resistance of the circuit
(d) all of the above

(x) Four identical 10 cm cylinders (A, B, C, and D) are filled with water to
shown in the figure. varying heights, as

D 8cm
C 6 cm
B 4 cm
A 2 cm

When a vibrating tuning fork is held above cylinder D, a loud sound is heard due to
resonance. If the tuning fork is now placed above cylinders A,,B and C, which cylinder(s)
willalso produce the loud sound?
(a) Cylinder A.
(b) Cylinder B.
(c) Cylinder C.
(d) Cylinders Aand C.
(xi) Large number of thin stripes of black paint are made on the surface of a convex lens of
focal length 20 cm to catch the image ofa white horse. The image will be:
(a) a white horse with black stripes.
(b) a white horse with reduced brightness
(c) a completely black horse.
(d) a white horse unaffected by the stripes.
(xii) Which circuit shows the correct and safe position for the fuse and switch?
Live wire
Live wire

Neutral wire
Neutral wire
(a) (b)
Live wire Live wire

Neutral wire
Neutral wire

(c) (d)

3
(xiii) A current-carrying wire, represented by "X" in the front view, is
between two magnets. The wire experiences a downward force, asplaced horizontally
fig. (1). shown in the adjacent

Current carrying
wire X

N
Fig. (L)

Force
If the same wire is positioned
perpendicularly tothe plane of the paper within the field of
a U- shaped magnet as shown in the fig. (2), what will be
on the wire?
the direction of the force acting

(a) Upward N
(b) Downward
(c) Into the plane of the paper
(d) Out of the plane of the paper Fig. (2)

(xiv) James takes two blocks, Block l and Block 2, made

ofdifferent metals, and heats them
until the temperature of both has increased by 30 CHe then places both
to cool. Block 2 has a greater thermal capacity than Block 1
blocks on a desk
Which block loses more energy as it cools to room
temperature?
Which block required more energy to raise its temperature by 30°C?
Lost more energy when c0olingRequired more energy to heat up
(a) block | block 1
(b) block 2 block 2
(c) block1 block 2
(d) block 2 block 1

(xv) Drinks are often cooled by adding ice cubes to them.

A delicious mocktail is initially at a temperature of
12 °C when a few ice cubes are added to it.

After some time, some of the ice melts, and the

temperature of the cocktail drops to 7°C.
What is the temperature of the remaining unmelted
ice?
(a) 7°C
(b) 5 °C
(c) 2 °C
(d) 0 °C

4
 Question 2
Complete the following by choosing the correct answers from the bracket.
(6]
() (a) A block and tackle pulley system consists of 'n'
pulleys, with the effort applied in
a convenient direction. If the load moves up by a
distance (d), the effort end moves
through a distance .[n/nd/ 2d]
(b) A spherical air bubble in water will act as
lens. [ convex/ concave /
plano-convex)
(c) vibrations occur when an object vibrates at its natural frequency
without external forces acting after the initial disturbance. fdamped /free /
resonant]
(d) A coil of an alloy is used in electric heater as aresistor. /tungsten /
constantan /nichrome]
(e) The direction of the magnetic field at the center offa
in the
circular.coil carrying current
direction ís along the axis of the coil and directed inward,
into the plane of the paper. [clockwise /anticlockwise / radial]
() Fifteen bulbs are connected in series. One bulb is fused and the
remaining 14 bulbs
are again joined in series and connected to the same supply. The intensity of light
will in the room./remain constant increase/ decrease].
(ii) Name the element and kind of nuclear reaction takes place in the following:
2]
(a) in the star
b) inthe nuclear reactor.
(ii) Abody of mass 10 kg is kept at a height of 10 m. It is allowed to fall and reach the 2]
ground.
(a) What is the total mechanical energy possessed by the body at the height 3 m
assuming it is africtionless medium?
(b) What is the kinetic energy possessed by the body just before hitting the ground?

Question 3
(i) While playing with a convex lens, Rudali observes a printed paper by holding the lens at (2]
two diferent distances: A and B. At distance A, the letters of the printed matter appear
magnified, while at position B, the paper begins to burn.
Which of the positions, Aor B, iscloserto the lens? Why?
(i) The light bulb in a torch glows when the torch is switched on. This occurs through a [21
sequence of energy transformations. Complete the series of transformations by filling
in the blanks:
Energy changes involved:
1. Chemical 2. 3. 4. Light
energy energy

5
(ii) A
current-carrying conductor PQ lies in the plane of the paper, as shown in the figure. (21
Points Aand Bare located within the magnetic ield of the conductor.
p

(a) Arivhich point does the magnetic field point into the plane of the paper and at
which point does it come out of the plane of the paper?
(b) Ifr >, where willthe magnetic field strength be greater?
(iv) A plastic cup contains 1000g of sand, a50-watt electric heater and a thermometer, as [2]
shown in the figure.

Thermometer

Electric
Plastic heater
cup Sand

If the heater is turned on for 4.2 minutes, raising the sand's temperature from 20 °C to 35
°C, calculate:

(a) the total energy supplied by the heater.

(b) the specific heat capacity of the sand.

(v) Astretched wire of length 0.8 mis fixed between two rigid supports and vibrates in two [2]
different modes, as shown in the figure.

(a) Which vibration will produce a 0.8m

louder sound? Is it vibration 1or
vibration 2?
Vibration 1

(b) What is the ratio of wavelengths of

vibration l and vibration 2? Vibration 2

6
(vi) (a) Name the product of nuclear fission which is utilized to bring about further
fission (21
of 2u.
(b) Why are gamma rays emitted only in nuclear processes and not in orbital electron
transitions?

(vii) The radioactive radiations were allowed to fall on photographic plate, placed in an electric (3]
field for few [econds. The photographic plate was developed and three distinct spots
(A, B and C) were visible.

NegativeDeveloped photographic
side plate
side
ive

ldentify radiations responsible for each spot with reasons.

SECTION B
(Attempt any four questions fromthis Section.)
Question4
() (a A
deep-sea diver tries to spear a fish underwater of density 1:025 g.cm-, 3)
Should he aim above, below or directly at the fish's observed position to makea
directhit?

(b) If the same diver aims at a bird flying near the water's surface, should he aim
above, below, or directly at the bird's observed position? Justify your answer.

7
(ii) Prutha saw rays of sunlight entering into a
dark room as shown in the figure. (31
She then did something to the air in the
room after which slhe was NOT able to see
the rays of sunlight in the room.

(a) What could Prutha have done to

make the sunlight rays invisible?
Justify your answer.
(b) Define the process or phenomenon
associated with the case mentioned
above in part (a).
(ii) (a) Khushi uses red colour of light to find the refractive index of
glass. She then 14]
repeats the experiment using green colour of light.
Will the refractive index be same or different in two
cases? Why?
(b) Complete the ray diagram to show the path ofa ray that travels
parallel to the
principal axis, as it enters, passes through, and exits the lens system.

Question 5
() Three wires with proper colour coding are connected to the [3
three terminals of athree-pin socket. Match the colour of the
wire with the proper terminals A, B and C of the socket. OA
(a) Brown
(b) Green BO
(c) Light blue

(ii) In the diagram, a narrow beam of white light is (3]

incident on a right-angled isosceles prism.
The critical angle of the material of prism for yellow
colour of white light is 45°.

Complete the ray diagram to show the path of Blue, 45°

Yellow and Red colours of white light till they emerge
out of the prism.

8
(ii) Astudent conducted an experiment to study the
placing an object at distances of 25 cm, 30cm, 40image formation by a convex lens by
cm, 60 cm and 41
lens. 120 cm in front of the
For each position of the object, he
recorded the image distance(v) from the lens.
However, the recorded image distances 100 cm, 24 cm, 60cm, 30 cm,
written in the wrong order. and 40 cm were

(a) Using the properties of a convex lens, find the

correct order of the image
corresponding to the given object distances and redraw the table with distances
corrected
result.
Object distance(u) Image distance(v)
-25 cm
-30 cm
-40 cm
-60 cm
-120 cm

(b) Calculate the focal length of the lens.

(c) What will be the image distance if the object is placed at the
distance of 90 cm?
Show the necessary calculations.

Question 6
) (a) Calculate the height through which a crane can lift a load of 4000 kg, when its
3]
motor of 4HP operates for l0 s. [Take l HP =746 watt, g =10 m.s]

(b) A moving body weighing 400 Npossesses 500 J of kinetic energy. Calculate the
velocity with which the body is moving. [Take g = 10ms]
(ii) Calculate the position of the fulcrum at which a uniform meter rule of mass 20 gf can be [3]
balanced when three weights 50 gf, 20 gf and 400 gf are applied at 10 cm, 40 cm and 80
cm respectively.

(ii) (a) Abody falls freely under gravity from rest. Name the kind of energy it will [4]
possess while falling.
(b) In a block and tackle system of pulleys, why does the mechanical advantage
increase with an increase in the number of pulleys?
(c) Why a ship loaded with light goods is more liable to be over turned than the one
loaded with heavy goods?

Question 7
() (a) Ablock and tackle system has 4 pulleys with a velocity ratio (VR) of 5. (3]
Draw a labelled diagram of the system, clearly indicating the direction of the load,
the effort and the components of tension.
 (b) What will be the velocity ratio (V.R.) of the above
system if the weight of the
movable block is doubled and the efforts are being applied in a
convenient
direction? Willit increase by I,decrease by Ior remain the same?
() The diagram shows a microphone being used to detect the output from a
loudspeaker. The 3)
oscilloscope trace shows the wave pattern produced by the loudspeaker
0.0001s

Loudspea ker

High frequency
signal generator
Microphone
Oscillos cope
(a) How many waves are produced by the Joudspeaker in 0.0001 seconds?
(b) How many waves are produced by the loudspcàker every second?
ASsume the
input to the loudspeaker does not change.
(c) Explain why a person with normal hearing cannot hear the sound produced by the
loudspeaker.
(ii1) An observer on an island is 5500 maway from a vertical cliff. Aship is anchored between
14]
the island and the cliff. When the ship's siren blasts, the observer hears the sound twice
with atime gap of 5seconds.

Cliff k 5500 m island

If the speed of sound is 330 m/s:

(a) Calculate the distance of the ship from the island.
(b) What is the distance of the ship from the cliff?
Question 8
) In the given circuit diagram: 3)
(a) Find the potential difference
across the battery terminals. R 62
(b) Determine the current
measured by the ammeter.
(c) Calculate the resistanceR.
6V 12 V

10
(i) (a) Complete the following radioactive reaction:
(3]
-X ’Y + He ’ z +e
(b) What is the importance of boron and
cadmium rods in a nuclear reactor?
(iii) The V-I graph for a nichrome wire is shown below.
[4]
(a) What do you infer from this
2.0
graph?
(b) What conditions must be S 16
maintained to ensure accurate
1.24
observations of the V-I
characteristic while verifying it 0,8

experimentlly? O 04+
(c) Draw a labelled circuit diagram to
obtain the given graph. 0
0.1 0.2 0.3 0.4 05 0.6
Current (A)

Question9
(i) Calculate the specific heat capacity.of 100g of oil ifitstemperature rises from 20 °C to
80 °C in 5minutes, The oil is heated by anichrome wire connected to a 10 V supply with (3]
a currentof 1.7 A.

(ii) (a) The melting point of naphthalene is 80 °C and the room temperature is 30 °C. 3)
Asample of liquid naphthalene at 100 °C is cooled down to room temperature.

Draw atemperature-time graph to represent this cooling process. In the graph,

mark the region that corresponds to freezing.
(b) Albert, Shivaniand Myra are analyzing the heating of two beakers, Xand Y, each
containing different liquids. Both beakers contain the same mass of liquid and
are heated using the same heater set to the same power.

The graph shows how the temperature of each liquid changes with time.
(°C)
Temperature
Based on the graph, each student makes the following conclusions:

Albert: Xhas a higher melting point than Y.

X
Shivani: Y boils sooner than X.
Myra: X has a lower specific heat capacity Y
than Y.

Who is correct and why? Time (s)

11
(ii) (a) In the following diagram, an arrow shows the motion of the coil towards the bar 14)
magnet.

Magnet
N

A B

1. Inwhich direction does the current flow in the coil: from Ato Bor from Bto A?
2. Ifa galvanometer is connected to a coil at points Aand B, how does the
galvanometer pointer deflect when the magnet and coil are moved rightward at the
speed of 30 m/s?

(b) The figure shows a magnetic compass needle aligning with the geographic north
south direction when placed far from the current-carrying solenoid Point Klies
within the mganetic field of the solenoid.

Magnetic
K needle

1. When the bompassneedle is brought 1o point K, which pole of the needle will
experience a repulsive force?
2. How can the strength of the magnetric field of this solenoid be increased without
adding more turns to the coil?

12