Class 10 Physics MCQ PYQ 2024–25 with Answers

✅ Correct Answer: (B) between pole and focus of the mirror.
📝 Explanation :
When an object is placed between the pole and the focus of a concave mirror, it forms a virtual, erect, and magnified image, which helps the dentist see enlarged teeth clearly.

Answer: (D) behind the mirror at a distance f/2 ✅
📝 Explanation:
For a convex mirror, the focal length is taken as positive.
Given:
Object distance, u = −f
Focal length, f = +f
Using the mirror formula:
1/f = 1/v + 1/u
1/f = 1/v − 1/f
1/v = 2/f
v = f/2
The positive value of v shows that the image is formed behind the mirror.
Hence, the image is formed behind the mirror at a distance f/2.

Answer: (B) −20 cm ✅
📝 Explanation:
Given:
Object distance (u) = −30 cm
Image distance (v) = −60 cm
(Image is real and inverted, formed in front of the concave mirror)
Using mirror formula:
1/f = 1/v + 1/u
1/f = 1/(−60) + 1/(−30)
1/f = (−1 − 2)/60
1/f = −3/60
1/f = −1/20
Focal length (f) = −20 cm

Answer: (C) ✅
📝 Explanation: A ray parallel to the principal axis of a concave mirror, after reflection, passes through the focus (F)

Answer: (A) (i) and (ii) ✅
📝 Explanation:
Mirror Y (convex mirror) forms a virtual, erect, and diminished image, suitable for rear-view mirrors
Mirror X (concave mirror) forms a real image at the focus when sunlight (parallel rays) is concentrated

Answer: (C) Real and magnified ✅
📝 Explanation:
Radius of curvature (R) = 40 cm
Focal length of concave mirror,
f = R / 2 = 40 / 2 = 20 cm
Object distance = 30 cm
Since the object is placed between F (20 cm) and C (40 cm),
a concave mirror forms a real, inverted, and magnified image.
Therefore, the image formed is real and magnified.

Answer: (c) 40 cm ✅
📝 Explanation:
Magnification (m) for a lens is given by:
m = v / u
Given magnification, m = −1
Negative sign shows that the image is real and inverted and |m| = 1 means the image is of the same size as the object.
For a convex lens, an image of the same size is formed when the object is placed at 2f.
Given focal length, f = 20 cm
So, object distance = 2f = 2 × 20 = 40 cm
Hence, the object must be placed at a distance of 40 cm.

Answer: (A)10/9 ✅
📝 Explanation: Refractive index of Y with respect to X

Answer: (C) b and e ✅
📝 Explanation:

• Angle of deviation is the angle between the incident ray and the emergent ray → e
• Angle of incidence is the angle between the incident ray and the normal at the first surface → b

Answer: (A)10/9 ✅
📝 Explanation: Refractive index of Y with respect to X

Answer: (D) 9/8 × 10⁸ m/s ✅
📝 Explanation:
Refractive index (n) = c / v
For glass:
n_g = c / v_g
c = n_g × v_g
c = (3/2) × 2 × 10⁸
c = 3 × 10⁸ m/s
For water:
v_w = c / n_w
v_w = (3 × 10⁸) / (4/3)
v_w = (9/8) × 10⁸ m/s

Answer: (A) Iris ✅
📝 Explanation: The iris controls the size of the pupil and hence regulates the amount of light entering the eye

Answer: (B) thin and its curvature is minimum ✅
📝 Explanation:
When we look at a distant object, the ciliary muscles relax.
As a result, the eye lens becomes thin.
In this condition, the curvature of the eye lens is minimum, allowing light from distant objects to focus on the retina.
Hence, the correct option is (B).

Answer: (D) Outer surface of Cornea ✅
📝 Explanation: The maximum refraction of light entering the eye occurs at the outer surface of the cornea

Answer: (B) concave lens ✅
📝 Explanation: Elongation of the eyeball causes myopia (near-sightedness), which is corrected using a concave lens

Answer: (B) the focal length of the eye lens has increased ✅
📝 Explanation: In hypermetropia, the eye lens cannot become sufficiently thick, so its focal length increases, making nearby objects appear blurred

Answer: (D) increases or decreases as the case may be ✅
Explanation: The ciliary muscles change the curvature of the eye lens to focus objects at different distances

Answer: (B) presbyopia and bifocal lens ✅
📝 Explanation: Weakening of ciliary muscles and reduced flexibility of the eye lens causes presbyopia, which is corrected using a bifocal lens

Answer: (A) scattering of light ✅
📝 Explanation: Smoke particles scatter the sunlight, making the path of light visible in the room

Answer: (A) Cornea ✅
📝 Explanation:
Most of the refraction of light entering the human eye occurs at the surface of the cornea

Answer: (C) Ciliary muscles ✅
📝 Explanation:
Ciliary muscles change the curvature of the eye lens to focus light from objects at different distances

Answer: (D) Green light deviates more than the orange light ✅
Explanation: In a prism, shorter wavelength light deviates more; hence green light deviates more than orange light

Answer: (D) 1 and 6 ✅
📝 Explanation:
Angle of deviation is the angle between the incident ray and the emergent ray → 6
Angle of incidence is the angle between the incident ray and the normal at the first surface → 1

Answer: (C) Blue ✅
📝Explanation:
Very fine dust particles scatter light of shorter wavelength more effectively.
Blue light has the shortest wavelength among the given options.
Therefore, blue light is scattered the most in a region containing very fine dust particles.

Answer: (C) blue ✅
📝 Explanation:
Very fine dust particles cause scattering of light.
Light of shorter wavelength scatters more than light of longer wavelength.
Among the given options, blue light has the shortest wavelength.
Hence, blue light is scattered the most.

Answer: (C) ✅
📝 Explanation:
The scattering of light by very fine particles in air depends on the wavelength of light.
According to Rayleigh scattering, light of shorter wavelength is scattered more strongly than light of longer wavelength.
Blue light has a shorter wavelength than red light.
Therefore, when sunlight passes through fine particles in air, blue light is scattered more than red light.

Answer: (B) Higher than that of its constituent metals ✅
Explanation:
Alloys have higher resistivity than pure metals because the presence of different atoms increases scattering of electrons, opposing current flow

Answer: (C) 9R ✅
📝 Explanation:
When a wire is stretched, its volume remains constant.
Let original length = L and original resistance = R
New length = 3L
Since volume is constant:
A × L = A’ × 3L
So, new area A’ = A / 3
Resistance R = ρL / A
New resistance R’ = ρ(3L) / (A/3)
R’ = 9 × (ρL / A)
R’ = 9R
Therefore, the new resistance of the wire is 9R.

Answer: (C) 9 Ω ✅
📝 Explanation:
Four identical resistors of resistance 12 Ω each are connected to form a square ABCD.
The resistance is to be calculated between points 1 and 2, which are connected to points A and B respectively.
Between points A and B, there are two possible paths for current flow:
Path 1 (Direct path A → B):
This path contains only one resistor of 12 Ω.
Path 2 (Long path A → C → D → B):
This path contains three resistors in series:
12 Ω + 12 Ω + 12 Ω = 36 Ω
Thus, the two paths between A and B have resistances 12 Ω and 36 Ω respectively.
Since both paths connect the same two points (A and B), they are in parallel combination.
Using the formula for equivalent resistance of two resistors in parallel:
R = (R₁ × R₂) / (R₁ + R₂)
R = (12 × 36) / (12 + 36)
R = 432 / 48
R = 9 Ω
Therefore, the resistance of the network between points 1 and 2 is 9 Ω.

Answer: (d) 9 ✅
📝 Explanation:
Let the original resistance of the wire be R.
When the wire is cut into three equal lengths, the length of each part becomes l/3.
Since resistance is directly proportional to length:
Resistance of each part = R / 3
The three equal resistors (each of resistance R/3) are connected in parallel.
Equivalent resistance R′ of three equal resistors in parallel is:
R′ = (R/3) / 3
R′ = R / 9
Therefore,
R / R′ = R / (R/9) = 9

Answer: (C) D/3 and L/6 ✅
📝 Explanation:
Resistance of a wire is given by:
R = ρL / A
For wires of the same material, resistivity (ρ) is constant.
Area of cross-section A ∝ D²
So,
R ∝ L / D²
Now compare each option:
(A) R ∝ L / D²
(B) R ∝ (L/4) / (D/2)² = L / D²
(C) R ∝ (L/6) / (D/3)² = (9/6) × L / D²
(D) R ∝ (L/12) / (D/4)² = (16/12) × L / D²
Option (C) gives the maximum value of resistance.
Hence, the resistance will be maximum when the diameter is D/3 and the length is L/6.

Answer: (B) 8000 J ✅
Explanation:
Given:
Resistance (R) = 40 Ω
Current (I) = 2 A
Time (t) = 50 s
Heat produced in a conductor is given by Joule’s law:
H = I² R t
Substituting the given values:
H = (2)² × 40 × 50
H = 4 × 40 × 50
H = 8000 J
Therefore, the heat produced in the wire is 8000 joules.

Answer: (a) 4400 Ω ✅
📝 Explanation:
Given:
Voltage (V) = 220 V
Power (P) = 11 W
Using the relation:
P = V² / R
So,
R = V² / P
R = (220 × 220) / 11
R = 48400 / 11
R = 4400 Ω
Hence, the resistance of the filament is 4400 Ω.

Answer: (c) 60 ✅
📝 Explanation:
Each bulb is rated at 4 V, which means it can safely operate at a maximum voltage of 4 V.
Total supply voltage = 240 V
When bulbs are connected in series, the supply voltage is divided equally among them.
Number of bulbs required = Total voltage / Voltage rating of one bulb
Number of bulbs required= 240 / 4
Number of bulbs required= 60
Therefore, a minimum of 60 identical bulbs must be connected in series to work safely with desired brightness.

Answer: (B) 110 W ✅
📝 Explanation:
Power (P) = V × I
P = 220 × 0.5
P = 110 W

Answer: (D) ✅
📝 Explanation:
A bar magnet, when suspended freely, always aligns itself in the north–south direction.
It has the ability to attract iron filings and produces magnetic field lines around it.
Outside the bar magnet, magnetic field lines emerge from the north pole and enter the south pole.
However, inside the bar magnet, the magnetic field lines run from the south pole to the north pole.
Therefore, statement (D) is not true.

Answer: (B) direction of current flowing through the solenoid ✅
📝 Explanation:
The strength of magnetic field inside a long straight current-carrying solenoid depends on:
* Number of turns per unit length of the solenoid
* Magnitude of current flowing through it
* Nature of the core material inside the solenoid
Changing the direction of current only reverses the direction of the magnetic field, but does not change its strength.
Therefore, the magnetic field strength does not depend on the direction of current.

Answer: (A) North ✅
📝 Explanation:
Explanation (Using Right-Hand Thumb Rule):

• Current flows from east to west.
• Point of observation is above the wire.
• According to the Right-Hand Thumb Rule:
  • Point the thumb of your right hand in the direction of current (east → west).
  • The curl of fingers gives the direction of the magnetic field.

👉 At a point above the wire, the curled fingers point towards the North.

✔ Magnetic field is directed towards North

Correct Answer: (D) ✅
📝 Explanation:
A current-carrying conductor experiences a force in a magnetic field only when the direction of current is not parallel to the magnetic field.
The force is maximum when the conductor is placed at right angles to the magnetic field.
If the conductor is placed along the direction of the magnetic field, no force acts on it.
Therefore, a uniform magnetic field exerts a force only when current flows through a conductor at right angles to the field.

Answer: (B) ✅
📝 Explanation:
In domestic electric circuits, standard colour codes are used for safety.
Red wire is used for the live (phase) connection.
Black wire is used for the neutral connection.
Green wire is used for the earth connection.
Hence, the correct colour combination is red for live, black for neutral and green for earth.