ISC Physics 2025 Improvement Paper with Answers
All 39 questions of the ISC Physics 2025 Improvement Paper, in printed order. Open a question to read it in full and see its answer.
- Q1(A)(i) Three cells having emfs $3\text{ V}$, $1\text{ V}$ and $4\text{ V}$ are connected as shown in Figure 1 below. Their internal… 1 mark · MCQ
- Q1(A)(ii) Magnetic field inside a long current carrying solenoid is $B_0$. If each of the current ($I$) and the number of turns ($N$) in… 1 mark · MCQ
- Q1(A)(iii) Study the data given below. Material Relative Permeability P 0.9999906 Q 1.000021 R 600 S 280,000 The material most suitable to… 1 mark · MCQ
- Q1(A)(iv) de Broglie wavelength of moving particles does not depend on their: 1 mark · MCQ
- Q1(A)(v) If temperature of a block of a semiconducting material is increased, its resistance: 1 mark · MCQ
- Q1(A)(vi) Phase difference between two overlapping waves to produce a bright band is $2\pi, 4\pi, 6\pi, 8\pi, \dots, 2n\pi$. 1 mark · Assertion-reason
- Q1(A)(vii) When a beam of white light is passed through a prism, it gets split into its constituent colours. 1 mark · Assertion-reason
- Q1(B)(i) What is the effect of increasing the temperature of a piece of metal on relaxation time of free electrons? 1 mark · Short answer
- Q1(B)(ii) Write an expression for Lorentz force in vector form. 1 mark · Short answer
- Q1(B)(iii) Identify the optical device shown in Figure 2 below. 1 mark · Short answer
- Q1(B)(iv) Figure 3 below shows an optical pin kept in front of a lens mirror combination. It is found that the final image formed by the… 1 mark · Drawing
- Q1(B)(v) How are energy (‘E’) and momentum (‘p’) of a photon related to each other? 1 mark · Short answer
- Q1(B)(vi) If radius of first Bohr orbit of an electron in hydrogen atom is $0.05\text{ nm}$, calculate the radius of its third orbit. 1 mark · Numerical
- Q1(B)(vii) State any one difference in the energy band diagram of a semiconductor and that of an insulator. 1 mark · Short answer
- Q2(i) Two resistors, $R_1 = 1\ \Omega$ and $R_2 = 2\ \Omega$ are connected in parallel. If the power developed in the resistor $R_1$ is… 2 marks · Numerical
- Q2(ii) In Figure 4 shown below, internal resistance of the battery is negligible. Calculate the Ammeter reading, assuming its resistance… 2 marks · Numerical
- Q3 Two identical capacitors, each of capacitance C are connected to a battery as shown in Figure 5 below. Calculate the equivalent… 2 marks · Short answer
- Q4(i) Three identical point charges, each equal to Q, are situated at the three vertices of an equilateral triangle MNO, having each… 2 marks · Short answer
- Q4(ii) Two Gaussian surfaces, $S_1$ and $S_2$ are shown in Figure 6 below. What is the ratio of electric flux emerging out of these two… 2 marks · Short answer
- Q5 How much force per unit length acts on a long current carrying conductor X due to a current flowing through another similar… 2 marks · Short answer
- Q6 A parallel beam of monochromatic light of wavelength $450\text{ nm}$ is incident normally on a rectangular slit of width… 2 marks · Numerical
- Q7 Name the electromagnetic wave emitted by the remote control operating the TV set. State any one property common to all… 2 marks · Short answer
- Q8 Intensity of monochromatic UV light incident on photocathode of a photoelectric cell is increased. What is its effect on… 2 marks · Short answer
- Q9 Derive an expression for electric field intensity (E) at a point which lies on the axis of an electric dipole (having length $2l$… 3 marks · Derivation
- Q10(i) The potentiometer has a driver cell D of emf $6\text{ V}$ and an internal resistance of $2\ \Omega$, as shown in Figure 7 below… 3 marks · Numerical
- Q10(ii) Two cells of emf $13\text{ V}$ and $12\text{ V}$ and negligible internal resistance are connected in the circuit shown in Figure… 3 marks · Numerical
- Q11 In a moving coil galvanometer, why is the magnetic field made radial? You are provided with one low resistance $R_L$ and one high… 3 marks · Drawing
- Q12(i) Using Ampere’s circuital law, obtain an expression for magnetic field ‘B’ at a point ‘P’ which is at a perpendicular distance… 3 marks · Derivation
- Q12(ii) Figure 9 below shows a metallic rod PQ resting on two parallel thick and smooth metallic rails CS and DR. There is a uniform… 3 marks · Short answer
- Q13 Two convex lenses having focal length of $1.5\text{ cm}$ and $5\text{ cm}$ are placed coaxially to form a compound microscope… 3 marks · Numerical
- Q14 With the help of a labelled diagram and Huygen’s wave theory, prove: When a parallel beam of light is incident obliquely on a… 3 marks · Derivation
- Q15 Shyam was performing a double slit experiment to determine wavelength of monochromatic light emitted by a laser. The examiner… 3 marks · Short answer
- Q16 Two identical thin convex lenses, each having an optical power of $2\text{ D}$ are kept in contact with each other. Calculate… 3 marks · Numerical
- Q17 The graph of stopping potential ($V_0$) versus frequency ($f$) of incident UV radiation incident on a metallic surface is shown… 3 marks · Numerical
- Q18(i) A choke coil has a self-inductance of $0.5\text{ H}$ and a resistance of $50\ \Omega$. It is connected to a $220\text{ V}$… 5 marks · Numerical
- Q18(ii) When current flowing through a solenoid increases from $0$ to $10\text{ A}$ in $0.2\text{ s}$, an emf of $20\text{ V}$ is induced… 5 marks · Short answer
- Q19(i) State Bohr’s postulate of quantisation of angular momentum. Show how it can be obtained from wave nature of orbiting electrons… 5 marks · Short answer
- Q19(ii) Write a balanced equation of a nuclear fission reaction taking place in a nuclear reactor. By performing necessary calculations… 5 marks · Short answer
- Q20 Discovery of semiconducting devices has revolutionised the field of electronics. Earlier, a computer known as first generation… 5 marks · Case based