SSLC SECOND TERM EXAM 2025
PHYSICS - ANSWER KEY
Summative Assessment - II Term, 2025-26
Standard: X
Time: 1½ hours
Total Score: 40
Code: E1006 PH
Section A (Questions 1-4, 1 score each)
Question 1
Which type of lens has a positive power?
Answer:
b) Convex lens
Explanation: Convex lenses converge light and have a positive power.
Question 2
Assertion: White light passing through a prism split into its component colours.
Reason: The deviation of different colours of light varies according to their wave length.
Reason: The deviation of different colours of light varies according to their wave length.
Answer:
a) Both assertion and reason are true, and reason is the correct explanation of assertion.
Explanation: Dispersion of white light occurs due to different wavelengths refracting at different angles.
Question 3
Which of the following is correct about magnetic poles in a current-carrying solenoid?
Answer:
b) ii and iv
Explanation: The poles of a solenoid depend on the direction of current flow.
Question 4
Match the parts of step-up transformer with their functions and structures.
Answer:
c) A - 3 - iii, B - 1 - ii, C - 2 - i
Explanation: Primary coil is input (thick wire), secondary coil is output (thin wire), core confines flux (soft iron).
Section B (Questions 5-11, 2 score each)
Question 5
The distance between two consecutive particles in the same phase of vibration in a transverse wave is 4 m. If a particle in the medium takes 5 s for 10 vibrations, what is the speed of this wave?
Answer:
Wave speed = 8 m/s
Explanation: Wavelength (λ) = 4 m, Time for 10 vibrations = 5 s → Time period (T) = 0.5 s → Frequency (f) = 2 Hz → Wave speed = f × λ = 2 × 4 = 8 m/s.
Question 6
A tuning fork is placed near a stretched string and made to vibrate. The string starts vibrating with the same frequency as the tuning fork. Give reason.
Answer:
Forced vibration / Resonance
Explanation: The tuning fork forces the string to vibrate at its natural frequency, causing resonance.
Question 7A
When a beam of light passes through a colloidal solution the path of the light becomes visible. Name the phenomenon and give another example.
Answer:
Phenomenon: Tyndall effectDaily life example: Sunlight through mist, headlights in fog, etc.
Question 7B
In which colours will a person view the Sun during sunrise, sunset and at noon? Explain.
Answer:
Morning & evening: Red/orangeNoon: White/yellow
Explanation: Scattering of light is higher at sunrise/sunset due to longer atmospheric path, leaving longer wavelengths (red) visible.
Question 8
A conducting wire AB is fixed vertically through the center of a cardboard.
Answer:
a) Negative terminalb) Right-hand thumb rule / Maxwell's corkscrew rule
Question 9
Explain why more heat energy is produced in the second circuit when time and voltage are the same.
Answer:
More heat in second circuit due to lower resistance (or higher current for same voltage), as per Joule's law H = I²Rt.
Question 10
What are the major steps to reduce carbon footprint in a new public transportation system?
Answer:
• Use electric/hybrid buses• Promote cycling/walking infrastructure
• Optimize routes for efficiency
• Use renewable energy for charging
Question 11A
When a magnet is moved towards a coil an emf is induced.
Answer:
a) Induced emf increases because rate of change of flux increases.b) Zero, because relative motion is zero.
Question 11B
A solenoid is placed in a changing magnetic field.
Answer:
a) Electromagnetic inductionb) Factors: Rate of change of magnetic flux, number of turns, area of coil
Section C (Questions 12-17, 3 score each)
Question 12A
An object is placed 20 cm away from a concave lens. The image is formed at a distance 10 cm from the lens. Find the focal length.
Answer:
f = -20 cm (negative for concave lens)
Explanation: Using lens formula 1/f = 1/v - 1/u, u = -20 cm, v = -10 cm → 1/f = 1/(-10) - 1/(-20) = -0.05 → f = -20 cm.
Question 12B
A concave lens has a focal length of 15 cm. An object is placed at 25 cm from the lens, image at 10 cm. Find magnification.
Answer:
Magnification m = 0.4 (diminished, virtual image)
Explanation: m = v/u = (-10)/(-25) = 0.4.
Question 13
The figure shows image formation when an object is placed at the near point of a person's eye.
Answer:
a) Hypermetropia (farsightedness)b) Corrected using convex lens
c) Near point farther than 25 cm
Question 14
Patients undergoing MRI scanning are asked to remove all jewellery made of metal.
Answer:
a) Strong magnetic field can attract metals, cause heating or movementb) Use shielding, proper design, safe distance
Question 15
Calculate total energy consumed in one day and cost for one month.
Answer:
Total power = 660 WEnergy per day = 5.28 kWh
Energy per month = 158.4 kWh
Cost = ₹792
Explanation: Total power = (5×60) + (2×80) + 200 = 660 W. Energy/day = 660 × 8 = 5280 Wh = 5.28 kWh. Energy/month = 5.28 × 30 = 158.4 kWh. Cost = 158.4 × 5 = ₹792.
Question 16
A heating appliance is rated 400 W, 240 V. If power produced is only 100 W, calculate operating voltage.
Answer:
Operating voltage = 120 V
Explanation: Using P = V²/R, R = 240²/400 = 144 Ω. For P = 100 W, V = √(P×R) = √(100×144) = 120 V.
Question 17A
Diagram of a generator is given.
Answer:
a) AC generator (commutator absent)b) Slip rings and brushes
c) AC, because relative motion still changes flux
Question 17B
Power stations produce electricity on a large scale.
Answer:
a) 11–25 kVb) Nuclear → heat → mechanical → electrical
c) Fuel burned → steam → turbine → generator → electricity
Section D (Question 18, 4 score)
Question 18A
In the figure, a conductor AB is arranged across two parallel copper wires placed on an acrylic sheet above a ring magnet.
Answer:
a) North pole at Xb) Fleming's left-hand rule
c) Reverse current direction or swap battery terminals
Question 18B
Diagram of an electric motor is given.
Answer:
a) South poleb) Diagram showing perpendicular vectors: B (field), I (current), F (force)
c) Reverse current direction in armature
d) Electrical → mechanical energy
Note: This answer key is based on standard physics principles and the given question paper. For official answers, please refer to the exam board's marking scheme.