ISC Physics 2025 Specimen Paper with Answers
All 39 questions of the ISC Physics 2025 Specimen Paper, in printed order. Open a question to read it in full and see its answer.
- Q1(A)(i) Figure 1 below shows a circuit containing an ammeter A, a galvanometer G and a plug key K. When the key is closed: 1 mark · MCQ
- Q1(A)(ii) A circular coil having N turns of radius R carrying a current I is used to produce a magnetic field B at its centre O. If this… 1 mark · MCQ
- Q1(A)(iii) Magnetic susceptibility of a diamagnetic substance: 1 mark · MCQ
- Q1(A)(iv) The de Broglie wavelength of an electron in the first Bohr’s orbit of hydrogen atom is equal to: 1 mark · MCQ
- Q1(A)(v) An ideal PN junction diode offers: 1 mark · MCQ
- Q1(A)(vi) An astronomical telescope has an objective lens having large focal length. 1 mark · Assertion-reason
- Q1(A)(vii) If critical angle of glass-air pair ($\mu_g = 3/2$) is $\theta_1$ and that of water-air pair ($\mu_w = 4/3$) is $\theta_2$, then… 1 mark · Assertion-reason
- Q1(B)(i) Current I flowing through a metallic wire is gradually increased. Show graphically how heating power (P) developed in it varies… 1 mark · Drawing
- Q1(B)(ii) Explain why core of a transformer is always laminated. 1 mark · Short answer
- Q1(B)(iii) Why does a car driver use a convex mirror as a rear-view mirror? 1 mark · Short answer
- Q1(B)(iv) Represent diagrammatically how the incident planar wavefronts of wavelength $\lambda$ pass through an aperture of size $d$, when… 1 mark · Drawing
- Q1(B)(v) What is meant by “Dual nature of matter”? 1 mark · Short answer
- Q1(B)(vi) What happens when an electron collides with a positron? 1 mark · Short answer
- Q1(B)(vii) What energy conversion takes place in a solar cell? 1 mark · Short answer
- Q2(i) A dielectric slab of dielectric constant $K$ and thickness $t$ is introduced between the two plates of a capacitor of… 2 marks · Short answer
- Q2(ii) In Figure 2 below, the current-voltage graphs for a conductor are given at two different temperatures $T_1$ and $T_2$. At which… 2 marks · Short answer
- Q3 Arrangement of an oxygen ion and two hydrogen ions in a water molecule is shown in Figure 3 below. Calculate electric dipole… 2 marks · Numerical
- Q4(i) Figure 4 below shows a part of an electric circuit. Apply Kirchhoff’s junction rule to the junction A to find current flowing… 2 marks · Short answer
- Q4(ii) In a potentiometer, a cell is balanced against $110\text{ cm}$ when the circuit is open. A cell is balanced at $100\text{ cm}$… 2 marks · Numerical
- Q5 Figure 5 below are two long, parallel wires carrying current in the same direction such that $I_1 < I_2$. In which direction will… 2 marks · Short answer
- Q6 The focal length of a double convex lens is equal to the radius of curvature of either surface. What is the refractive index of… 2 marks · Short answer
- Q7 Name the electromagnetic radiation that has been used in obtaining the image below. What is the wavelength range of… 2 marks · Short answer
- Q8 How does stopping potential in photoelectric emission vary if the intensity of the incident radiation increases? the frequency of… 2 marks · Short answer
- Q9 “A uniformly charged conducting spherical shell for the points outside the shell behaves as if the entire charge of the shell is… 3 marks · Short answer
- Q10(i) Study the two circuits shown in Figure 6 below. The cells in the two circuits are identical to each other. The resistance of the… 3 marks · Numerical
- Q10(ii) The drift velocity of electrons in a conductor connected to a battery is given by $v_d = -eE\tau/m$. Here, $e$ is the charge of… 3 marks · Short answer
- Q11 A galvanometer of resistance $100\ \Omega$ gives a full-scale deflection for a potential difference of $200\text{ mV}$. What must… 3 marks · Numerical
- Q12(i) A student records the following data for the magnitudes ($B$) of the magnetic field at axial points at different distances $x$… 3 marks · Short answer
- Q12(ii) An electron moving along positive X axis with a velocity of $8 \times 10^7\text{ ms}^{-1}$ enters a region having uniform… 3 marks · Numerical
- Q13 With the help of a neatly drawn labelled diagram, prove the law of reflection on the basis of Huygen’s wave theory. 3 marks · Derivation
- Q14 A lens of focal length $f$ is divided into two equal parts and then these parts are put in a combination as shown in Figure 8… 3 marks · Short answer
- Q15 In Young’s double slit experiment, how is interference pattern affected when the following changes are made: Slits are brought… 3 marks · Short answer
- Q16 A virologist studies details of a virus with the help of an instrument. Name the instrument used by him. Draw a labelled ray… 3 marks · Short answer
- Q17 The graphs below show the variation of the stopping potential $V_S$ with the frequency ($\nu$) of the incident radiations for two… 3 marks · Derivation
- Q18(i) The magnetic field through a single loop of wire, $12\text{ cm}$ in radius and $8\cdot 5\ \Omega$ resistance, changes with time… 5 marks · Numerical
- Q18(ii) Three students, X, Y and Z performed an experiment for studying the variation of a.c. with frequency in a series LCR circuit and… 5 marks · Short answer
- Q19(i) Find the binding energy per nucleon of $^{235}\text{U}$ based on the information given below. Mass (u) mass of neutral… 5 marks · Numerical
- Q19(ii) Define unified atomic mass unit. Calculate its energy equivalent. In an atom X, electrons absorb the energy from an external… 5 marks · Numerical
- Q20 Sanya performed an experiment of obtaining characteristic curves of a junction diode. When she forward biased it, she found that… 5 marks · Case based