ICSE Class 10 Physics — 2023 Paper

Negative

Reason — If the effect on the body is to turn it clockwise, moment of force is called the clockwise moment and it is taken as negative, while if the effect on the body is to turn it anticlockwise, moment of force is called the anticlockwise moment and it is taken as positive.

becomes four times

Reason — According to the formula :

Kinetic energy = $\frac{1}{2}$mv²

Hence, when speed (v) is doubled the kinetic energy increases by 4 times.

electrical to mechanical

Reason — In a washing machine, electrical energy changes into mechanical energy.

Beta radiations

Reason — Beta radiations suffer maximum deflection in a magnetic field.

more than violet light

Reason — Speed of violet light is minimum and speed of red light is maximum. Hence, speed of blue light in water is more than violet light.

virtual, diminished

Reason — A concave lens always forms a virtual and diminished image.

forced vibration

Reason — When a body vibrates under a periodic force, the vibrations of the body are always forced vibration.

Waveform

Reason — Different instruments produce different subsidiary notes. A note played on piano has a large number of subsidiary notes, while the same note played on violin does not contain so many subsidiary notes. Hence, they have different waveforms.

I²Rt

Reason — When a current I flows through a wire of resistance R for time t then the electrical energy produced is given by I²Rt.

V < ε [when the cell is in use]

Reason — When a cell is used to send current to an external circuit, it's terminal voltage V is less than it's e.m.f.

Hence, terminal voltage < e.m.f.

increases

Reason — The strength of magnetic field produced can be increased by increasing the current.

depends on the material

Reason — Specific latent heat of a substance depends on the material.

1 kg of substance X absorbs 1900 J heat for 1°C rise in temperature

Reason — Specific heat capacity of a substance X is 1900 Jkg^-1°C^-1 means 1 kg of substance X absorbs 1900 J heat for 1°C rise in temperature

0°

Reason — The ray of light incident normally on a plane glass slab passes undeviated, ( i.e. such a ray suffers no bending at the surface). Thus, if angle of incidence ∠i = 0°, then the angle of refraction ∠r = 0°.

total internal reflection

Reason — Small air bubbles rising up a fish tank appear silvery when viewed from some particular angle because of the phenomenon of total internal reflection.

(a) The nucleus of an atom becomes radioactive when number of neutrons in the nucleus exceeds the number of protons in it.

(b) Single movable pulley.

(c) Advantage of this type of pulley is that we can lift a heavier load with a small effort.

(a) The centre of gravity for a triangular lamina is at the point of intersection of the medians.

(b) When the triangular lamina is suspended freely from any one vertex, the moment of force produced by its own weight in its rest position is zero. This is because the center of gravity of the triangular lamina is at the point where its medians intersect and the triangle is in rotational equilibrium. Hence, we get zero moment of force.

(a) Force F₁ produces the maximum moment.

(b) Moment of force = force x perpendicular distance from the point of application of the force to the pivot point.

As the three forces are equal in magnitude, the magnitude of moment of force will depend on the perpendicular distance from the point of application of the force to the pivot point.

The perpendicular distance from the line of action of F₁ to the pivot point A is equal to the diameter of the wheel, while the perpendicular distance from line of action of F₂ and F₃ is less than the diameter, therefore, the moment produced by F₁ will be greater than the moments produced by F₂ and F₃.

(a) 180°

(b) As gravitational potential energy [U] = mgh

Hence, $\frac{U}{h}$ = mg

Therefore, the physical quantity obtained is weight of the object.

Given,

mass = 2000 kg

velocity = 1.5 ms^-1

weight or downward force = mg = 2000 x 10 = 20,000 N

From formula, P = F x v

P = 20,000 x 1.5 = 30,000 W = 30 kW

Hence, power spent by the crane = 30 kW.

(a) The vibrations produced are known as damped vibrations.

(b) If we place the ruler partially off the table then a shorter length of the ruler is free to vibrate, hence the frequency of vibration increases. The shorter the length of the ruler, the higher the frequency of its natural vibrations.

It means that if the geyser is operated on a 220 V supply, the electric power consumed by it is 240 W i.e., 240 J of electric energy is consumed by the geyser in 1 s.

(a) No.

(b) The focal length of the lens will not change.
Reason — The focal length of a lens is a characteristic property of the lens itself and is determined by its shape and refractive index. Covering a portion of the lens with opaque paper will not alter the lens's inherent optical properties.

(a) Miniature circuit breaker [MCB] can be used to protect the electric circuit in case of excess current and can also be used as a switch.

(b) The MCB is always connected in series with the live wire in the household circuit.

(a) The magnetic poles at the points A and B should be of opposite polarity for the conductor to experience the force in the upward direction. So, if point A is North pole then point B should be South pole and vice versa.

(b) Fleming's left hand rule can be used to find these polarities.

(a) B will have more specific heat capacity.
Reason —

$$\begin{aligned}\text{Specific heat capacity (c)} = \frac{\text{Heat Capacity of body (C')}}{\text{mass of body (m)}} \\[1em] \therefore \text{Specific heat capacity (c)} ∝ \frac{1}{\text{mass}}\end{aligned}$$

∴ Specific heat capacity of B will be more as its mass is less.

(b) Both substances will show equal rise in temperature as their thermal capacities are the same.

The radioactivity of a radioactive isotope is not affected by chemical changes. This is because radioactivity is a nuclear phenomenon specifically related to the stability of the isotope's nucleus, while chemical changes involve the rearrangement of electrons and the formation or breaking of chemical bonds.

(a) Given,

angle of prism (A) = 60° for an equilateral prism.

angle of incidence (i₁) = 65°

Angle of deviation (δ) = 43°

𝑒 = i₂ = ?

From formula,

Angle of deviation (δ) = 𝑖 + 𝑒 − 𝐴

Substituting the values we get:

43 = 65 + i₂ - 60°

i₂ = 43 - 5 = 38°

Hence, i₂ = 38°

(b) Emergent ray

Below is the completed diagram showing the path of the light ray till it emerges out of the prism with all angles marked:

(a) Ray B (Blue) will bend more than ray A (Orange) as shown in the diagram below:

(b) In glass, speed of orange (A) light is more than that of blue light (B).

(c) The two refracted rays are not parallel in glass as orange light with more speed bends less while blue light with slow speed bends more.

Given, focal length = 10 cm

Image distance (v) = 60 cm

Object distance (u) = ?

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,

$$\begin{aligned}\frac{1}{60} - \frac{1}{\text{u}} = \frac{1}{10} \\[1em] \Rightarrow \frac{1}{60} - \frac{1}{10} = \frac{1}{\text{u}} \\[1em] \Rightarrow \frac{1 - 6}{60} = \frac{1}{\text{u}} \\[1em] \Rightarrow \frac{-5}{60} = \frac{1}{\text{u}} \\[1em] \Rightarrow \frac{1}{\text{u}} = \frac{-1}{12} \\[1em] \Rightarrow u = -12\end{aligned}$$

∴ The object should be placed at a distance of 12 cm in front of the lens.

(a) Given, µ=$\frac{4}{3}$

Shift = 3.0 mm

We know,

refractive index = $\frac{\text{real depth}}{\text{apparent depth}}$

$\frac{4}{3}$ = $\frac{\text{x}}{\text{apparent depth}}$

apparent depth = $\frac{\text{3x}}{4}$

Shift = real depth - apparent depth

$$\begin{aligned}3 = \text{x} - \frac{\text{3x}}{4} \\[1em] \Rightarrow 3 = \frac{\text{4x - 3x}}{4} \\[1em] \Rightarrow 3 = \frac{\text{x}}{4} \\[1em] \Rightarrow \text{x} = 4 \times 3 = 12\end{aligned}$$

∴ Depth of coin in water = 12 mm

(b) Critical angle [C] = sin^-1 $\frac{1}{μ}$

(a) Infrared radiations are used for signals during war because they are not visible and they are not absorbed much in the medium.

(b)

1. Dispersion.
2. The cause of dispersion of white light is the change in speed of light with wavelength.
   When white light passes through a glass prism, its constituent colours (red, orange, yellow, green, blue, indigo, violet) travel with different speeds in the prism because each colour has different wavelength. This causes the dispersion of light.

(a) Labelled diagram of the block and tackle system of pulleys with velocity ratio 4 is shown below:

(b) The load is being supported by four segments of the string. Therefore, L = 4T and E = T

∴ M.A. = $\frac{\text{load}}{\text{effort}}$ = $\frac{4\text{T}}{\text{T}}$ = 4

(a) Given, wt of scale = 50 gf

Let wt. from [0 to 40] cm be W₁ and [40 to 100] cm be W₂

W₁ + W₂ = 50

⇒ W₁ = 50 - W₂ .....(1)

In equilibrium,

Anti-clockwise moment = Clockwise moment

(40 - 0) × W₁ = (100 - 40)W₂

40W₁ = 60W₂

40 [50 - W₂] = 60W₂ [.....From (1)]

40 x 50 - 40W₂ = 60W₂

2000 = 60W₂ + 40W₂

2000 = 100W₂

W₂ = $\frac{2000}{100}$

W₂ = 20 gf

Now, W₁ = 50 - 20 = 30 gf

∴ [0 to 40 cm] part of ruler weighs 30 gf.

Hence, the part [ 0 to 50 cm] of the ruler will weigh more 25 gf.

(b) Given the metre scale balances at 40 cm mark, so its weight of 50 gf acts at 40 cm mark.

Its weight of 50 gf produces anticlockwise moment about the centre.

Let the minimum weight needed be m.

In equilibrium,

Anti-clockwise moment = Clockwise moment

50 x (50 - 40) = m x (100 - 50)

⇒ 50 x 10 = m x 50

⇒ m = $\frac{50 \times 10}{50}$

⇒ m = 10 gf

Hence, minimum weight needed to balance the metre ruler when it is pivoted at its centre = 10 gf.

(a) Given,

Initial velocity (v_i) = 18 km/h

Converting km/h to m/s

18 x $\frac{5}{18}$ = 5 m/s

Final velocity (v_f) = 54 km/h

Converting km/h to m/s

54 x $\frac{5}{18}$ = 15 m/s

Work done = Change in kinetic energy = $\frac{1}{2}$m(v_f² - v_i²)

= $\frac{1}{2}$ x 120 x (15² - 5²)

= $\frac{1}{2}$ x 120 x (225 - 25)

= 60 x 200 = 12000 J

Hence, work done = 12000J

(b) Power = $\frac{\text{work done}}{\text{time}}$ = $\frac{12000}{5}$ = 2400 watt.

Hence, power of engine = 2400 watt.

(a) Loudness.

(b) Given,

Velocity = 1.5 kms^-1

Time = 14 sec

Distance = $\frac{\text{velocity} \times \text{time} }{2}$

(As the wave travels to the target and back so distance covered will be half of the distance travelled by the wave.)

Substituting values in the above formula we get,

Distance covered = $\frac{1.5 \times 14}{2}$

= 1.5 x 7 = 10.5 km

Hence, distance covered by the Ultrasonic wave = 10.5 km.

(a) ²³⁸₉₂P ⟶ ²³⁴₉₀Q + ⁴₂He ⟶ ²³⁴₉₁R + ⁰_-1e

(b) Alpha (α) radiations have the highest ionizing power.

(a) Resonance.

(b) 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.

(c) Air in sound box vibrates with higher amplitude due to vibrating string of musical instruments. This is an example of resonance.

(a) Specific resistance of a material is the resistance of a wire of that material of unit length and unit area of cross section.

(b) Specific resistance of the wire remains unchanged since it does not depend on the dimensions of the wire. It is the characteristic property of the substance.

(c) Manganin.

(a) γ (Gamma) radiation

(b) The nuclear reactor of the power plant must be shielded with thick lead and steel walls.

(c) Radioactive substances such as potassium (K-40), carbon (C-14) and radium present inside our body.

(a) As, the two 15Ω resistors are in series

So, R_s = 15 + 15 = 30Ω

Now, R_s (i.e., 30Ω) and 30Ω are in parallel,

$$\begin{aligned}\therefore \frac{1}{\text{R}_p} = \frac{1}{30} + \frac{1}{30} \\[1em] = \frac{2}{30} \\[1em] = \frac{1}{15}\end{aligned}$$

∴ R_p = 15Ω

Now, total resistance of the circuit = 2Ω + 15Ω = 17Ω

$$\begin{aligned}\text{I} = \frac{\text{emf}}{\text{total resistance}} \\[1em] = \frac{3.4}{17} \\[1em] = 0.2 \text{ A}\end{aligned}$$

∴ Current I = 0.2 A

(b) Terminal voltage [V] = emf - Ir
= 3.4 - [0.2 x 2] = 3.4 - 0.4
= 3 V

Hence, terminal voltage = 3 V

Given,

m = 200 g

specific heat capacity of water = 4.2 J g^-1 K^-1

specific latent heat of ice = 336 J g^-1

total amount of heat energy required = ?

Heat energy taken by ice at 0° C to convert into water at 0° C
= m x L
= 200 × 336
= 67200 J

Heat energy taken by water to raise the temperature from 0° C to 100° C
= m x c x change in temperature
= 200 × 4.2 × (100 - 0)
= 200 × 4.2 × 100
= 84000 J

Total heat energy gained is
= 67200 + 84000
= 1,51,200 J

Hence, total amount of heat energy required = 1,51,200 J

(a) When a hot body is brought in contact with a cold body, then heat lost by the hot body is equal to the heat gained by the cold body, provided there is no heat loss in the environment.

(b) Thin sheets of copper.

(c) The specific heat capacity of the material should be very low.

(a) Polarity of A is positive and B is negative.
Reason — Since at the left side of the loop, the lines of force are anti-clockwise, so, by right hand thumb rule we find that the current is going out of terminal A hence, it is positive. Similarly, at the right side of the loop, the lines of force are clockwise, so, terminal B is negative.

(b) The strength of the magnetic field increases when an iron rod is held along the axis of the coil.

(c)

1. By reversing the direction of the current.
2. By decreasing the current.