ICSE Class 10 Physics — 2024 Paper

kinetic energy to sound energy

Reason — When you ring a cycle bell, you apply a force (mechanical/kinetic energy) by pressing or rotating the lever. This mechanical movement causes a metal striker to hit the bell, producing sound energy.

5 N

Reason —

Given,

Length of lever = Perpendicular distance of the line of action of the force = 0.2 m
Moment of force = 1 Nm
As, Moment of force = Force × Perpendicular distance of the line of action of the force

1 = force x 0.2

force = $\frac{1}{0.2}=\frac{10}{2}$ = 5 N

5m

Reason — The amount of work done by a force is equal to the product of the force and the displacement of the point of application of the force in the direction of force. In the diagram, the object moves from point A to point C in the direction of force F. The straight-line path from A to C is 5 m, which is the magnitude of the displacement vector. Hence, the correct length to use as displacement is 5 m.

128

Reason — In β – particle emission, number of nucleons (i.e., sum of number of protons and number of neutrons) remains the same.

A is true but R is false.

Explanation

Assertion (A) is true: Scattering of light is inversely proportional to the fourth power of its wavelength (Scattering ∝ $\frac{1}{\text λ^4}$)

Since ultraviolet radiation has shorter wavelength than microwave radiation which implies ultraviolet radiations will be scattered more than microwave radiation.

Reason (R) is false: Ultraviolet radiation has a much shorter wavelength (around 10–400 nm) than microwaves (which have wavelengths in the millimeter to centimeter range, i.e., 1 mm to 1 m).

forced vibrations

Reason — When the stem of a vibrating tuning fork is pressed against the top of a table, the tuning fork produces forced vibrations in the table top as the table top has a much larger vibrating area than the tuning fork, so the forced vibrations of the table top send forth a greater energy and produces a louder (or more intense) sound than that produced by the tuning fork.

Human forearm

Reason — Human forearm is a class III lever because like class III lever, the elbow joint acts as fulcrum at one end, biceps exerts the effort in the middle and load on the palm is at the other end. Thus, this is an example of class III lever.

material

Reason — Specific resistance (also called resistivity, denoted by ρ) is a material property of a conductor and does not depend on its dimensions. It depends on :

1. The type of material (like copper, aluminium, iron, etc.)
2. Temperature (resistivity can change with temperature)

But it does not depend on :

1. Length
2. Area of cross-section
3. Radius

Reason — As colour coding for live wire is brown and for neutral wire it is blue so while connecting mains to an appliance a switch or a key must be connected with the live wire to ensure safety.

terminal voltage

Reason — In a closed electric circuit (i.e., when current is drawn), the potential difference between the terminals of a cell is called the terminal voltage which is less than the electromotive force (emf) of the cell due to the voltage drop across the internal resistance of the cell.

energy is absorbed and temperature remains constant.

Reason — When ice melts at 0°C, it absorbs heat energy from the surroundings which is used completely for phase change from solid (ice) to liquid (water) so this energy does not increase the temperature during the process.

m < 1

Reason — A concave lens always forms a virtual, erect, and diminished image of an object which means the size of the image is smaller than the size of the object and as magnification is the ratio of the length of image to the length of object so linear magnification of a concave lens is always less than 1.

Remain unchanged

Reason — Radioactive decay is a nuclear process as it depends on the nucleus of the atom, not on external physical conditions like pressure, temperature, chemical state and presence of air or vacuum. So, placing a radioactive element in an evacuated chamber (a vacuum) will not affect the rate of its decay.

Heat capacity

Reason — When no energy is lost to the surrounding, the amount of heat energy supplied is directly proportional to the change in temperature △t i.e.

$$\begin{aligned}\text Q ∝ △\text t\\[1em] \text {or} \\[1em] \text Q = \text {mc} △\text t\end{aligned}$$

Where,

m : mass of a substance

c : specific heat capacity of the substance

So,

$$\begin{aligned}\frac {\text Q}{△\text t} = \text {mc} \\[1em] \text {Slope of Q vs △\text t graph} = \frac {\text Q}{△\text t} = \text {mc}\end{aligned}$$

And mc is the heat capacity (C) of the body

Hence, slope of Q vs △t graph gives the value of the heat capacity.

Move away from the slab

Reason — When a converging beam of light enters a glass slab, the rays will bend towards the normal within the glass, and then bend away from the normal as they exit the glass back into air. This bending will cause the point of convergence (focus) to shift away from the glass slab.

(a) C¹⁴ is radioisotope of C¹² and C¹³ while O¹⁶, N¹⁴ and He⁴ are stable nuclei.

C¹⁴ is used to determine the age of ancient biological materials, such as fossils, bones, or archaeological samples (up to about 50,000 years old).

(b) CLass II lever.

(a) When a stone tied to a string is rotated in a horizontal plane, the tension in the string provides centripetal force necessary for circular motion.

(b) Work done by this force at any instant is zero .

Given,

Weight (W) = 120 N

From the figure,

Distance of C.G. from the pivot point O = r = 0.20 m

Distance of F from the pivot point O = R = 0.80 m

Now,

Moment of force about pivot point O due to C.G. = r x W = 0.20 x 120 = 24 Nm (clocKwise direction)

and

Moment of force about pivot point O due to F = R x F = 0.80 x F (anticlocKwise direction)

For equilibrium,

Anticlockwise moment of force due to F about pivot point O = Clockwise moment of force due to C.G. about pivot point O

$$\begin{aligned}0.80 \times \text F = 24 \\[1 em] \Rightarrow \text F = \frac{24}{0.80}= \frac{240}{8} =30\ \text N\end{aligned}$$

So, value of F = 30 N.

(a) A block and tackle system with multiple pulleys provides a higher mechanical advantage, which means less effort is required to lift a heavy load compared to a single movable pulley since in a single movable pulley, mechanical advantage (M.A.) is 2 but in a block and tackle system with 9 pulleys, the M.A. can go up to 9 (ideally), making it much easier to lift heavier loads with the same effort.

(b) To ensure smooth and balanced operation, more pulleys should be in the upper fixed block because :

1. It reduces the weight of the movable block, making it easier to lift.
2. It helps in maintaining stability and reduces oscillation during lifting.
3. It also makes arrangement and threading of ropes more efficient and manageable.

Given,

Work done by Sumit (W_S) = 600 J

Time taken by Sumit (t_S) = 10 min = 10 x 60 = 600 seconds

Work done by Amit (W_A) = 300 J

Time taken by Amit (t_A) = 20 min = 20 x 60 = 1200 seconds

Then,

Power delivered by Sumit (P_S) = $\frac{\text {Work done by Sumit}\ (\text W_\text S)}{\text {Time taken by Sumit}\ (\text t_\text S)} =\frac{600}{600} = 1\ \text W$

and

Power delivered by Amit (P_A) = $\frac{\text {Work done by Amit}\ (\text W_\text A)}{\text {Time taken by Amit}\ (\text t_\text A)} =\frac{300}{1200} = 0.25\ \text W$

So,

$\frac{\text P_\text S}{\text P_\text A}=\frac{1}{0.25} =4$

(a) In a series connection, total resistance is the sum of individual resistances.

Let resistance of each bulb be R.

Initially :

R_total = 5R

After removing one bulb:

R_total = 4R

So, resistance will decrease.

(b) When resistance decreases, total current in the circuit (assuming the same voltage supply) will increase :

$\text I = \frac{\text V}{\text R}$

So, more current → more power delivered to each bulb.

Since,

Power (P) = I²R,

Hence, intensity of light increases for each remaining bulb.

Given,

Speed of sound in oxygen = 340 ms^-1

Speed of sound in benzene = 200 ms^-1

Minimum distance required to hear an echo = distance sound travels in 0.1 s (since the human ear can distinguish sound if the reflected sound reaches after 0.1 s)

So,

$\text {Minimum distance for echo} = \frac{\text {Speed of sound}\times \text {Minimum time to hear an echo}}{2}=\frac{\text v \times \text t_\text{min}}{2}$

and

t_min = 0.1 sec

For medium containing oxygen :

$\text x = \frac{340\times 0.1}{2}=\frac{34}{2} = 17\ \text m$

For medium containing benzene :

$\text y = \frac{200\times 0.1}{2}=\frac{20}{2} = 10\ \text m$

So, from above calculations x > y.

(a) In a reading glass, the object is placed between the optical center and the principal focus of the convex lens to produce a virtual and enlarged image of the object so that a magnified view of the object can be seen.

(b) A concave lens always forms a virtual, erect, but diminished (smaller) image of the object so it cannot magnify the object.

Given,

Maximum current passing through the fuse (I_max) = 5 A

Input voltage of the geyser (v) = 220 V

Power rating of the geyser (P) = 1540 W

Let, current passing through geyser be I.

Then,

$$\begin{aligned}\text P = \text {IV} \\[1em] \text I = \frac{\text P}{\text V}=\frac{1540}{220}=7\ \text A\end{aligned}$$

As,

I_max = 5 A < I = 7 A

So if the fuse is used with the geyser then it will draw more current greater than the maximum current and in turn fuse will melt.

No, the fuse can not be used with the geyser

The speed of rotation of coil can be increased by the following two ways :

1. by increasing the strength of current in the coil,
2. by increasing the number of turns in the coil.

Given,

m = 500 g

latent heat of fusion of ice (L) = 330 J g⁻¹

Let, required heat be Q.

Then,

$\text Q = \text {mL} = 500 \times 330 = 165000\ \text J = 165\ \text {kJ}$

As only neutrons are involved in the reaction which number of protons and total nucleon number (i.e., number of protons + neutrons) remain constant.

Then,

Initially,

No. of protons (n_p) = Atomic number of $_{92}\text{U}^{235}$ = 92

No. of nucleons (n) = Mass number of $_{92}\text{U}^{235}$ + mass number of $_0\text n^1$ = 235 + 1 = 236

Now,

Finally,

Let atomic number of Kr is Z and mass number of Ba is A.

No. of protons (n_p) = Atomic number of $_{56}\text{Ba}^{\text A}$ + Atomic number of $_{\text Z}\text{Kr}^{92}$ = 56 + Z

and

No. of nucleons (n) = mass number of $_{56}\text{Ba}^{\text A}$ + mass number of $_{\text Z}\text{Kr}^{92}$ + 3 x mass number of $_0\text n^1$ = A + 92 + 3 = A + 95

As number of protons are constant :

⇒ 92 = 56 + Z

⇒ Z = 92 - 56 = 36

Also, number of nucleons are constant :

⇒ 236 = A + 95

⇒ A = 236 - 95 = 141

So reaction will be :

$_{92}\text{U}^{235} + _0\text{n}^1 \longrightarrow _{56}\text {Ba}^{141} + \space _{36}\text {Kr}^{92} + 3 \space _0\text n^1$

Given,

Object distance (u) = - 36 cm

As, image is formed on a screen then,

Image distance (v) = + 72 cm

Let, focal length be f.

From lens formula,

$$\begin{aligned}\frac{1}{\text f} = \frac{1}{\text v} - \frac{1}{\text u} \\[1 em] \frac{1}{\text f} = \frac{1}{72}-\frac{1}{(-36)}=\frac{1}{72}+\frac{1}{36}= \frac{1+2}{72} \\[1em] \frac{1}{\text f} = \frac{3}{72} \\[1 em] \text f = \frac{72}{3} = + 24 \text { cm}\end{aligned}$$

Now,

$\text {Power} = \frac{1}{\text {f (in metre)}} = \frac{1}{24\times 10^{-2}}=\frac{100}{24} ≈ 4.17\ \text D$

Gamma ray	X – ray	U V rays	Visible rays	Infrared	Micro Waves	Radio waves

(a) Radiation A : Micro Wave

(b) X – rays are used to detect fracture in bones.

(c) Micro waves and radio waves are part of electromagnetic waves.

(a) Red colour is used as a danger signal on the top of a skyscraper because red light has the longest wavelength among visible light, so it is scattered the least by air molecules and dust and remains visible from a long distance and in low visibility, making it ideal for danger signals.

(b)

Here, the refracted ray PQ is normal to the surface AB of the prism (i.e., ∠r = 0°), so the incident ray at the point P should also be normal to the surface AB so that ∠i = 0°.

At point Q, the angle of incidence for the ray PQ = 133° - 90° = 43°

Now, this angle should be equal to the critical angle because ray PQ is refracted at 90°, i.e., it is refracted along QC. Hence, the critical angle of the prism is 43°.

2. In △AРQ

∠APQ + ∠PQA + ∠PAQ = 180°

⇒ 90° + 47° + ∠PAQ = 180°

⇒ ∠PAQ = 180° - 90° - 47°

⇒ ∠ PAQ = 43°

Hence, ∠A= 43°

3. As the light used and its wavelength determine the angle of deviation since with a decrease in the light wavelength, the angle of deviation increases so the beam will experience total internal reflection if we swap out the blue light with lower wavelength i.e., indigo.

(a) Given,

Refractive index of glass with respect to water = $\frac{9}{8}$

Then, according to the principle of reversibility of light

Refractive index of water with respect to glass =
$\frac{1}{\text {Refractive index of glass w.r.t water}} = \frac{1}{\frac{9}{8}}=\frac{8}{9}$

(b) Principle of reversibility of light

(c) If temperature is changed of water then the ratio $\frac{9}{8}$ will also change as refractive index of medium is inversely proportional to the temperature i.e., on increasing temperature refractive index of a medium decreases and vice versa.

So, If we change the temperature of water,then the ratio $\frac{9}{8}$ will not remain the same.

(a) False because speed of light in vacuum is highest and diamond is a denser medium so speed of light will be lower and hence, it can not travel a distance 20x in diamond which is two times of distance travelled by light in vacuum.

(b) Given,

Distance travelled by light in vacuum = 10x

Time taken by light in vacuum = t₁

Distance travelled by light in the medium = x

Time taken by light in diamond = t₂

As,

$\text {Speed of light in vacuum (c)} = \frac {\text {Distance travelled by light in vacuum}}{\text {Time taken by light in vacuum}}= \frac {10\text x}{\text t_1}$

and

$\text {Speed of light in diamond (v)} = \frac {\text {Distance travelled by light in diamond}}{\text {Time taken by light in diamond}}= \frac {\text x}{\text t_2}$

then,

$$\begin{aligned}\text {The refractive index of diamond} = \frac{\text{Speed of light in vacuum (c)}}{\text {speed of light in diamond (v)}}= \frac{\frac {10\text x}{\text t_1}}{\frac {\text x}{\text t_2}} \\[1em] =\frac{10 \text t_2}{\text t_1}\end{aligned}$$

(a) In below figure, I is the position of source O when seen through the surface RS.

(b) The angle of deviation depends on the following factors :

1. the angle of incidence (i),
2. the material of prism (i.e., on refractive index μ).

(a) The centre of gravity (C.G.) of a body is the point about which the algebraic sum of moments of weights of all the particles constituting the body is zero and the entire weight of the body can be considered to act at this point, howsoever the body is placed.

(b)

1. As the centre of gravity of a hollow cone is at h/3 from its base on its axis where h is the height of the cone.

Given,

Height of the cone (h) = 6 cm

Centre of gravity of cone = $\frac{\text h}{3} = \frac{6}{3} = 2 \text{ cm}$

2. Yes, now cone is a solid cone. So, the position of the new center of gravity from the base will be h/4 сm i.e. $=\frac{6}{4} = 1.5\ \text{ cm}$ from the base of the cone.

(a) As Path 2 is rough and Path 1 is frictionless then marble A will surely reach the top because there will be no energy lost on the frictionless road while some energy will be degraded om rough path.

(b) As total mechanical energy remains constant when there is no frictional force, hence, mechanical energy will be preserved along path 1.

(c) Since energy cannot be created or destroyed, the law of conservation of energy applies to both scenarios.

(a) The diagram is given below :

(b)

1. Given,

Velocity Ratio = 2

Load = 48 kgf

Efficiency = 80% = 0.8

As,

$$\begin{aligned}\text {Efficiency} = \frac {\text {Mechanical Advantage}}{\text {Velocity Ratio}}\\[1 em] ⇒ \text {Mechanical Advantage} = \text {Efficiency} \times \text {Velocity Ratio}=0.8 \times 2 = 1.6\end{aligned}$$

2. As,

$$\begin{aligned}\text {Mechanical Advantage} = \frac{\text {Load}}{\text {Effort}}\\[1 em] ⇒ \text {Effort} = \frac{\text {Load}}{\text {Mechanical Advantage}}= \frac{48}{1.6}=30 \text { kgf}\end{aligned}$$

(a) Ultrasonic Waves.

(b) The closest cliff produces the first echo. However, the first cliff, or cliff A, is only 10 meters away from the Lata, and a minimum of 17 meters is required between the cliff and the listener in order to hear an echo.

Then, echo will be heard from Cliff B

Given,

Speed of sound in air (v) = 320 ms^-1

Distance of Lata from cliff B (d) = 160 m

Total distance travelled = 2d = 2 × 160 = 320 m

Time = $\frac{2\text d}{\text v}=\frac {320}{320}$ = 1 sec.

Hence, the first echo will be heard after 1 second.

(a) $_{92}^{238}\text X \rightarrow _{90}^{234}\text Y + _{2}^{4}\text {He} \rightarrow _{91}^{234}\text Z + _{-1}^{0}\text e$

(b) Comparatively speaking, U-235 is easier to fission than U-238 because only fast neutrons can cause the fission of U-238, whereas slow neutrons can even trigger the fission of U-235.

(a) Resonance.

(b) The loud sound is audible at this specific length because the tuning fork's frequency and the air column's frequency are equal at that particular length.

(c) Since, frequency of the air column is inversely proportional to the length of the column therefore, in order to create a loud sound, the length of the air column should decrease as the frequency increases.

(a) The conductor is non-ohmic.

(b) As, from Ohm's Law

For V = 10 V and I = 2 A

$\text R = \frac{\text V}{\text I}=\frac{10}{2}= 5\ \text Ω$ ....... Equation 1

For V = 20 V and I = 3 A

$\text R = \frac{\text V}{\text I}=\frac{20}{3}= 6.67\ \text Ω$ ....... Equation 2

For V = 30 V and I = 4 A

$\text R = \frac{\text V}{\text I}=\frac{30}{4}= 7.5\ \text Ω$ ....... Equation 3

From equations 1, 2 and 3

Here, the ratio V/I is not constant and plot of V vs I graph will not be linear but if a conductor is an ohmic conductor then V/I should be constant to follow Ohm's law and V vs I graph should be linear which is not the case here.

Hence, the conductor does not follow Ohm's law and is a non-ohmic conductor.

(iii) Ohm's law states that the current flowing through the conductor is directly proportional to the potential difference across it's ends provided that the physical conditions and the temperature of the conductor remain constant.

(a) As from the diagram, the number of turns at primary coil is greater than that at secondary coil so this is a step down transformer.

(b) The secondary wire is more thicker than the primary since this is a step down transformer which reduces the voltage and increases the current at secondary coil so the use of a thicker wire reduces its resistance and therefore reduces the loss of energy as heat in that coil.

Given,

V = 4 V

Let,

R₁ = 10 Ω,

R₂ = 6 Ω,

R₃ = 12 Ω and

R₁ = 4 Ω

(a) As, R₁ and R₂ are in series then

R_S = R₁ + R₂ = 10 + 6 = 16 Ω

Similarly,

R₃ and R₄ are also in series,

R_S' = R₃ + R₄ = 12 + 4 = 16 Ω

Now, R_S and R_S' are in parallel combination then

$\frac{1}{\text R_\text{eq}}=\frac{1}{\text R_\text{S}}+\frac{1}{\text R_\text{S'}} = \frac{1}{16}+\frac{1}{16}=\frac{2}{16}$

⟹ ${\text R_\text{eq}} = \frac{16}{2} = 8\ \text Ω$

So, total resistance of the circuit is 8 Ω.

(b) From Ohm's law :

$\text {Current (I)} = \frac{\text V}{\text R_\text{eq}}=\frac{4}{8}=0.5\ \text A$

Current drawn from the cell is 0.5 A.

(c) As potential difference across 10 Ω and 6 Ω resistances is same as potential difference across 12 Ω and 4 Ω resistances which is V = 4 V.

Now,

$\text {Current through 10 Ω resistance} = \frac{\text V}{\text R_\text{S}}=\frac{4}{16}=0.25\ \text A$ .....equation 1

and

$\text {Current through 12 Ω resistance} = \frac{\text V}{\text R_\text{S'}}=\frac{4}{16}=0.25\ \text A$ .....equation 2

From equations 1 and 2

Current through 10 Ω resistance = Current through 12 Ω resistance = 0.25 A

So, the current through 10 Ω resistor is equal to the current through the 12 Ω resistor.

Given,

For Water

Mass of water (m_w) = 85 g

Initial temperature (T_i) = 30°C

Final temperature (T_f) = 5°C

Specific heat capacity of water (c_w) = 4.2 J g⁻¹ °C⁻¹

For ice

Initial temperature (T_i) = 0°C

Final temperature (T_f) = 5°C

Specific latent heat of fusion (L_i) = 336 J g⁻¹

Let,

Mass of ice = (m_i)

Now,

Heat lost by water = m_wc_w△t

= 85 × 4.2 × (30 - 5)

= 85 × 4.2 × 25 = 8925 J

Heat gained by ice = m_iL_i + m_ic_w△t

= m_i × 336 + m_i × 4.2 × (5-0)

= 336m_i + m_i × 4.2 × 5

= 336m_i + 21m_i = 357m_i

By principle of calorimetry,

Heat lost by water = Heat gained by ice

⟹ 8925 = 357 m_i

⟹ m_i = $\frac{8925}{357}$ = 25 g

So, the mass of required ice is 25 g.

(a) The surroundings become pleasantly warm when water in a lake starts freezing because the specific latent heat of fusion of ice is very high, hence large quantity of heat is released when the water in the lake freezes. Therefore, the temperature of the surrounding becomes pleasantly warm.

(b) The average kinetic energy of the molecules decreases as water freezes to produce ice because the temperature of the water molecules drops, and they hold to one another to form a crystal.

(c) 1 g of water at 0° C has more heat energy because 1 g of water at 0° C liberates 80 cal heat to form 1 g of ice at 0° C.

(a) Magnitude of magnetic field intensity affects the magnitude of induced current in an AC generator.

(b)

1. Right hand thumb rule.

2. Since the compass is pointing west, the current will flow from X to Y in an anticlockwise direction.

3. The amount of current flowing through the circuit will decrease if the resistance increases and the magnetic field then decreases as the magnetic lines of force surrounding the conductor is directly proportional to the current in the circuit.