ICSE Class 10 Physics — 2024 Specimen

positive

Reason — The anticlockwise moment is taken as positive while the clockwise moment is taken as negative.

momentum

Reason — As kinetic energy = $\frac{1}{2}$ mv ²

If we multiply and divide by m then we get, $\frac{\text{(mv)}^2}{2\text{m}}$

As mv = momentum (p), so

kinetic energy = $\frac{\text{p}^2}{2\text{m}}$

Therefore, kinetic energy of a given body depends on the momentum.

chemical to heat to mechanical to electrical.

Reason — A thermal power station is a type of power station in which heat energy is converted to electrical energy.

Here, the chemical energy of coal is changed into heat energy, which is transferred to steam. Then the heat energy of steam changes into mechanical energy of turbine that is further changed into electrical energy.

protons = 93, neutrons = 144

Reason — An alpha particle consists of two protons and two neutrons. Emission of alpha particle reduces the number of protons by 2 and also the number of neutrons by 2. Hence, number of protons = 95 - 2 = 93 and number of neutrons = 146 - 2 = 144.

both assertion and reason are true.

Reason — Infrared radiations travel long distances through dense fog and mist as they undergo minimal scattering in earth's atmosphere.

4f

Reason — When the object is kept at 2F₁, then, its image is formed at 2F₂. This is the position of minimum distance between object and image (i.e., 2f + 2f = 4f).

X will be grave and Y will be shriller.

Reason — The shrillness of a sound wave is directly proportional to its frequency, meaning that higher frequencies result in shriller sounds and lower frequencies result in grave sound.

forced vibrations

Reason — The vibrations of a body which take place under the influence of an external periodic force acting on it, are called forced vibrations. E.g. the vibrations produced in the diaphragm of a microphone sound box with frequencies corresponding to the speech of the speaker, are the forced vibrations.

P

Reason — The coil of a toaster should produce a high heating effect so its resistance should be high. From the graph, slope of line for substance P is the greatest hence, resistance of P is highest. So, substance P is most suitable for making the coil of a toaster.

green

Reason— In the old colour convention, green colour is used for earth wire.

energy

Reason — Lenz's law is based on the law of conservation of energy. It shows that the mechanical energy is spent in doing work against the opposing force experienced by the moving magnet, and it is transformed into the electrical energy due to which current flows in the solenoid.

the energy needed to raise the temperature of the body by 1°C

Reason — The term heat capacity of a body is the amount of heat energy required to raise it's temperature by 1° C (or 1 K). The S.I. unit of heat capacity is joule per kelvin (J K^-1)

latent heat of fusion

Reason — Heat energy absorbed in change of phase that is not externally manifested by any rise in temperature is called the latent heat of fusion.

the speed of light increases

Reason — The speed of light increases when it enters from a denser medium to a rarer medium. Lower density of the rarer medium causes less interaction between photons and particles. This reduces the scattering and results in a higher speed.

total internal reflection.

Reason — Total internal reflection is the principle that allows light to propagate through the core of an optical fiber by continuously reflecting off the inner walls of the fiber due to the angle at which it strikes those walls.

(a) A lever works on the principle of moments, according to which in the equilibrium position of levers, moment of load about the fulcrum must be equal to the moment of effort about the fulcrum and the two moments must be in opposite directions.

(b) Gamma radiations emitted during the decay of a nucleus have the highest penetrating power.

(c) When gamma radiations are emitted from the nucleus then there is no change in mass number as gamma radiations have no charge and mass.

(a) Centre of gravity of the given rod lie between 0 to 50.

(b) In equilibrium ,

(F₁) x distance (l₁) = (F₂) x distance (l₂)

As, F₁ > F₂

Hence, l₁ < l₂

Therefore, centre of gravity lies between 0 to 50.

(a) It is a class III lever.

(b) Mechanical advantage = $\frac{\text{effort arm}}{\text{load arm}}$ = $\frac{0.1}{0.1 + 0.4}$

$$\begin{aligned}= \frac{0.1}{0.5} \\[1em] = \frac{1}{5} \\[1em] = 0.2\end{aligned}$$

Considering Body A:

Let mass of body A = m_a = 4m

Let kinetic energy of body A = K

Let velocity of body A = V_a

Considering Body B:

Mass of body B = m_b = m [∵ mass of A is four times the mass of B]

Kinetic energy of body B = K [∵ A and B have same kinetic energies]

Let velocity of body B = V_b

Given, A and B have same kinetic energies,

∴ $\frac{\text{1}}{\text{2}}$ 4mV_a² = $\frac{\text{1}}{\text{2}}$mV_b²

4mV_a² = mV_b²

$$\begin{aligned}\frac{\text{V}_a^2}{\text{V}_b^2} = \frac{\text{1}}{\text{4}} \\[1em] \Rightarrow \frac{\text{V}_a}{\text{V}_b} = \sqrt{\frac{\text{1}}{\text{4}}} \\[1em] \Rightarrow \frac{\text{V}_a}{\text{V}_b} = \frac{1}{2}\end{aligned}$$

Hence, V_a : V_b = 1 : 2 or velocity of body B is two times the velocity of body A.

Graph of potential energy vs height from the ground for a body thrown vertically upwards is shown below:

(a) Let the length of wire B be L and that of A be 2L

R= ρ$\frac{\text{length}}{\text{area}}$

As area and specific resistance (ρ) are same for both wires A and B,

Hence,

$\frac{\text{R}_a}{\text{R}_b}$ = $\frac{\text{l}_a}{\text{l}_b}$ = $\frac{\text{2L}}{\text{L}}$ = $\frac{\text{2}}{\text{1}}$

Hence, the ratio between resistances A and B is 2 : 1

(b) Both the wires will have the same specific resistance because the specific resistance is a characteristic property of the material and as both the wires are of copper hence both will have same specific resistance.

(a) The waves used for echo depth sounding are ultrasonic waves.

(b) Ultrasonic waves can travel undeviated through a long distance and so they are used for echo depth sounding.

(a) The two materials bend the incoming rays by different amounts and produce two focal points. Hence, two images are formed.

(b) Concave lens because irrespective of the position of the object, the image formed by a thin concave (or divergent) lens is always virtual, upright, diminished, and it is situated on the side of the object between the focus and the lens.

(b) Concave lens

(a) Two advantages of this arrangement are :

1. Each appliance operates independently without being affected by the presence or working of the other appliances.
2. Each appliance gets connected to 220 V supply (= its voltage rating) for its normal working.

(a) Step down transformer

(b) turns ratio is n < 1, i.e., number of turns in the secondary are less than the number of turns in the primary.

Given,

Mass of solid (m) = 60 g

Fall in temperature of solid = (100 - 25) = 75°C

Rise in temperature of water = (25 - 20) = 5°C

Let specific heat capacity of solid be c.

Heat energy given by solid = mc△t
= 60 x c x 75 = 4500 x c .....(1)

Heat energy taken by water = 150 × 4.2 × 5 = 3150 .....(2)

Assuming that there is no loss of heat energy,

Heat energy given by solid = Heat energy taken by water.

Equating equations 1 & 2, we get,

$$\begin{aligned}4500 \times c = 3150 \\[0.5em] c = \frac{3150}{4500} \\[0.5em] c = 0.7 \text{ J g}^{-1} \text{K}^{-1} \\[0.5em]\end{aligned}$$

specific heat capacity of the solid = 0.7 J g^-1 K^-1

Heat capacity of solid = mass (m) x specific heat capacity = 60 x 0.7 = 42 J K^-1

Hence, Heat capacity of solid = 42 J K^-1

The radioactive material after its use such as nuclear power generation, nuclear weapons production, and nuclear medicine is known as nuclear waste.

The nuclear waste obtained from laboratories, hospitals, scientific establishments or power plants must be first kept in thick casks and then they must be buried in the specially constructed deep underground stores. These underground stores must be far away from the populated areas.

(a) Total Internal Reflection

Reason — The image of the fish seen at the surface of water is due to total internal reflection as shown in the ray diagram below:

(b) Below diagram shows the completed path of the ray till it emerges out of the prism:

(a) In general, the refractive index of a substance decreases with increasing temperature. Therefore, if the temperature of water is increased by 40°C, the refractive index 'x' is expected to be lesser than 1.33. Hence, we can state that x < 1.33.

(b) Two differences between normal reflection and total internal reflection are:

S. No.	Normal reflection	Total internal reflection
1.	Normal reflection can occur whenever light encounters a reflective surface, such as a mirror, glass, or water, without any specific conditions related to the angle of incidence.	Total internal reflection occurs when light travelling in a denser medium, is incident at the surface of a rarer medium at an angle of incidence greater than the critical angle for the pair of media.
2.	In normal reflection, only a part of the light is reflected while rest is refracted and absorbed. So, the reflection is partial.	In total internal reflection, the entire incident light is reflected back into the denser medium. So there is no loss of light energy.

(a) Refraction

The change in direction of the path of light when it passes from one transparent medium to another transparent medium, is called refraction.

(b) The shift X,

1. increases when Y increases
2. decreases when Y decreases.

(a) Real and inverted image is formed.

(b) Given, focal length = 8 cm

Object distance (u) = -24 cm

Image distance (v) = ?

From lens formula —

$$\begin{aligned}\frac{1}{v} - \frac{1}{u} = \frac{1}{f} \\[1em]\end{aligned}$$

Substituting the values in the formula we get,

$$\begin{aligned}\frac{1}{\text{v}} - \frac{1}{-24} = \frac{1}{8} \\[1em] \frac{1}{\text{v}} + \frac{1}{24} = \frac{1}{8} \\[1em] \frac{1}{\text{v}} = \frac{1}{8} - \frac{1}{24}\\[1em] \Rightarrow \frac{1}{\text{v}} = \frac{3 - 1}{24} \\[1em] \Rightarrow \frac{1}{\text{v}} = \frac{2}{24} \\[1em] \Rightarrow \frac{1}{\text{v}} = \frac{1}{12} \\[1em] \Rightarrow v = 12\end{aligned}$$

∴ The image is formed at a distance of 12 cm behind the lens.

(a) When sunlight passes through water droplets in the atmosphere or through a prism, violet light shows the maximum angle of deviation, while red light shows the minimum angle of deviation.

(b) The colour of emergent ray will be green. A prism does not change the colour of light. It just disperses white light into its constituent colours.

(a) The ray will pass through different points on principle axis after refraction through the convex lens. Red colour will deviate the least, followed by green and then blue will deviate the most.

(b) Ultraviolet radiations. Ultraviolet radiations are used for sterilising air, surgical equipment, etc.

(c) Infrared radiation.

(a) At equilibrium clockwise moment = anticlockwise moment

Moment = force x perpendicular distance

Wt. of Sachin's bag x OP = Wt. of Sumit's bag x OR

As OR < OP. Hence, Wt. of Sumit's bag > Wt. of Sachin's bag.

Hence, Sumit's bag is heavier than Sachin's bag

(b) Given,

Wt. of Sumit's bag = 18 kgf

Let wt. of Sumit's bag be W

At equilibrium,

Clockwise moment = Anticlockwise moment

W x OP = 18 x OR

W = $\frac{18 \times \text{OR}}{\text{OP}}$

(a) The completed diagram is given below:

(b) η = 80% given

V.R. = n = 3,

M.A. =?

η = $\frac{\text{M.A.}}{\text{V.R.}}$

$\frac{\text{80}}{\text{100}}$ = $\frac{\text{M.A.}}{\text{3}}$

M.A. = $\frac{\text{80}}{\text{100}}$ x 3= $\frac{\text{240}}{\text{100}}$ = 2.4

Given,

h = 5 m

m = 200 g = 0.2 kg

g = 10 ms^-2

(i) Potential energy U_B at B is given by

U_B = m x g x h

Substituting the values we get,

U_B = 0.2 x 10 x 5 = 10 J

Hence, the potential energy of the pendulum at the position B = 10 J

(ii) Total mechanical energy at point C = 10 J

The total mechanical energy is same at all points of the path due to conservation of mechanical energy.

(iii) At A, bob has only kinetic energy which is equal to potential energy at B,

Therefore,

$$\begin{aligned}\frac{1}{2} \times m \times (v_A)^{2} = U_B \\[0.5em] 0.5 \times 0.2 \times (v_A)^{2} = 10 \\[0.5em] (v_A)^{2} = \frac{10}{0.1} \\[0.5em] \Rightarrow v_A = \sqrt{100} \\[0.5em] \Rightarrow v_A = 10 \text{ m s}^{-1}\end{aligned}$$

(a) Let the distance of the cliff from the initial position of the person be x m.

Time after which echo is heard = 3 sec

So, the distance travelled by sound in 3 sec = 2x m

Speed of sound in air = 336 m/s

Distance = speed x time

Substituting the values we get,

$$\begin{aligned}2x = 336 \times 3 \\[1em] \Rightarrow x = \frac{336 \times 3}{2} \\[1em] \Rightarrow x = 168 \times 3 \\[1em] \Rightarrow x = 504 \text{ m}\end{aligned}$$

∴ The initial distance of the person from the cliff is 504 m.

(b) As time taken to hear the echo is increased by 1.5 sec, hence, the person has moved away from the cliff.

Let the distance moved by the person from his initial position be y m.

Time after which echo is heard = 1.5 + 3 = 4.5 sec

New distance = 504 + y

So, the distance travelled by sound in 4.5 sec = 2(504 + y) m

Speed of sound in air = 336 m/s

Distance = speed x time

Substituting the values we get,

$$\begin{aligned}2(504 + y) = 336 \times 4.5 \\[1em] \Rightarrow 504 + y = \frac{336 \times 4.5}{2} \\[1em] \Rightarrow y = (168 \times 4.5) - 504 \\[1em] \Rightarrow y = 756 - 504 \\[1em] \Rightarrow y = 252 \text{ m}\end{aligned}$$

∴ Distance moved by the person = 252 m

(a) ^A_ZX ⟶ ^A-4_Z-2X₁ + ⁴₂He ⟶ ^A-4_Z-1X₂ + ⁰_-1e ⟶ ^A-4_ZY + ⁰_-1e

We can see from the above that X and Y have same atomic number. Hence, X and Y will occupy the same position in the periodic table.

(b) Isotope.

(c) When the atomic no of Y = 80 and X and Y are isotopes then atomic no. of X will also be 80.

(a) Resonance
Definition — When the frequency of the externally applied periodic force on a body is equal to its natural frequency, the body readily begins to vibrate with an increased amplitude. This phenomenon is known as resonance.

(b) Loudness, when resonance occurs the loudness increases as the amplitude of the vibration is increased.

(c) 1 MHz = 10⁶ Hz
93.5 MHz = 93.5 x 10⁶ Hz = 9.35 x 10⁷ Hz

(a) The switch is always connected to the live wire. In above diagram, wire B is connected to switch so wire B must be the live wire.

(b) No, the fuse will not serve its purpose. In the diagram, the fuse is connected to the earth wire and not the live wire. In case of overload, the excess current will first pass through the oven damaging it and after that will flow through the fuse.

(c) It means that if the bulb is operated on a 220 V supply, the electric power consumed by it is 600 W i.e., 600 J of electric energy is consumed by the bulb in 1 s.

(a) ²²²₈₆Rn ⟶ ²¹⁸₈₄Po + ⁴₂X

(b) Radiation X are alpha particles. So, they will be deflected towards the negative plate when passed through an electric field.

(a) 5Ω and 3Ω are in series so their equivalent resistance (R_s) = 5 + 3 = 8Ω

Now 2Ω and R_s are in parallel.

$$\begin{aligned}\frac{\text{1}}{\text{R}_\text{p}} = \frac{\text{1}}{\text{R}_\text{s}} + \frac{\text{1}}{\text{2}} \\[1em] \Rightarrow \frac{\text{1}}{\text{R}_\text{p}} = \frac{\text{1}}{\text{2}} + \frac{\text{1}}{\text{8}} \\[1em] \Rightarrow \frac{\text{1}}{\text{R}_\text{p}} = \frac{4+1}{8} \\[1em] \Rightarrow \frac{\text{1}}{\text{R}_\text{p}} = \frac{5}{8} \\[1em] \therefore \text{R}_\text{p} = \frac{8}{5} = 1.6 \space Ω\\[1em]\end{aligned}$$

From circuit diagram,

Internal Resistance = 0.4 Ω

Total resistance of circuit = 1.6 + 0.4 = 2 Ω

(b) Current drawn from the battery

$$\begin{aligned}\text{I} = \frac{\text{e.m.f}}{\text{Total Resistance}} \\[1em] = \frac{4}{2} = 2 \text{ A}\end{aligned}$$

Now, the current I divides in 2 parts.

Let current across 2Ω be I₁ and across the series combination of 5Ω and 3Ω be I₂

I = I₁ + I₂ = 2 A .....(1)

Terminal Voltage of cell V = IR_p = 2 x 1.6 = 3.2 V

∴ P.d. across 2 Ω resistor = 3.2 V

I₁ = $\frac{3.2 \text{ V}}{2 \text{ Ω}}$

= 1.6 A

Substituting value of I₁ in Eq 1,

2 = 1.6 + I₂

⇒ I₂ = 2 - 1.6 = 0.4 A

Hence, current across 3Ω = 0.4 A

Given,

m_w = 2.1 kg = 2100 g

Specific heat capacity of water = 4.2 Jg^-1 C^-1

Specific latent heat of ice = 336 Jg^-1

m_i = ?

Heat energy given out by water in lowering it's temperature from 75° C to 25° C
= m x c x change in temperature
= 2100 x 4.2 x (75 - 25)
= 2100 x 4.2 x 50
= 4,41,000

Heat energy taken by m kg ice to melt into water at 0° C
= m_i x L
= m_i x 336

Heat energy taken by water at 0° C to raise it's temperature to 25° C
= m_i x c x change in temperature
= m_i x 4.2 x (25 - 0)
= m_i x 4.2 x 25
= m_i x 105

heat energy released = heat energy taken

Substituting the values we get,

4,41,000 = (m_i x 336) + (m_i x 105)

⇒ 4,41,000 = 336m_i + 105m_i

⇒ 4,41,000 = 441m_i

⇒ m_i = $\frac{441000}{441}$

⇒ m_i = 1000 g or 1 Kg

Hence, the mass of ice added = 1 Kg

(a) Substance condenses at 150° C

(b) 150 to 60°C

(c) 1 g of ice at 0° C takes 336 J of heat energy from the drink to melt into water at 0° C. Thus, the drink liberates an additional 336 J of heat energy to 1 g ice at 0° C than to 1 g ice-cold water at 0° C. Therefore, cooling produced by 1 g ice at 0° C is much more than that by 1 g water at 0° C.

(a) North pole
Reason — When the magnet leaves the coil, then as per Lenz's law, the bottom end of the coil develops south pole hence top end of the coil develops north pole.

(b) Direction will be from B to A
Reason — When the magnet leaves the coil, then as per Lenz's law, the direction of induced current in the coil will try to oppose it. Hence, it will be in the opposite direction to what it was when the magnet entered the coil. So, direction of induced current will be from B to A.

(c) Lenz's law

(d) Increasing the number of turns in the coil.