ISC Physics 2018 Question Paper with Answers
All 40 questions of the ISC Physics 2018 Question Paper, in printed order. Open a question to read it in full and see its answer.
- Q1(A)(i) The order of coloured rings in a carbon resistor is red, yellow, blue and silver. The resistance of the carbon resistor is: 1 mark · MCQ
- Q1(A)(ii) A circular coil carrying a current $I$ has radius $R$ and number of turns $N$. If all the three, i.e. the current $I$, radius $R$… 1 mark · MCQ
- Q1(A)(iii) An object is kept on the principal axis of a concave mirror of focal length $10\text{ cm}$, at a distance of $15\text{ cm}$ from… 1 mark · MCQ
- Q1(A)(iv) Einstein’s photoelectric equation is: 1 mark · MCQ
- Q1(A)(v) In Bohr's model of hydrogen atom, radius of the first orbit of an electron is $r_0$. Then, radius of the third orbit is: 1 mark · MCQ
- Q1(B)(i) In a potentiometer experiment, balancing length is found to be $120\text{ cm}$ for a cell $E_1$ of emf $2\text{V}$. What will be… 1 mark · Numerical
- Q1(B)(ii) How will you convert a moving coil galvanometer into a voltmeter? 1 mark · Short answer
- Q1(B)(iii) A moving charged particle $q$ travelling along the positive x-axis enters a uniform magnetic field $B$. When will the force… 1 mark · Short answer
- Q1(B)(iv) Why is the core of a transformer laminated? 1 mark · Short answer
- Q1(B)(v) Ordinary (i.e. unpolarised) light is incident on the surface of a transparent material at the polarising angle. If it is partly… 1 mark · Short answer
- Q1(B)(vi) Define coherent sources of light. 1 mark · Short answer
- Q1(B)(vii) Name a material which is used in making control rods in a nuclear reactor. 1 mark · One word
- Q2 Define current density. Write an expression which connects current density with drift speed. 2 marks · Short answer
- Q3(a) A long horizontal wire P carries a current of 50A. It is rigidly fixed. Another wire Q is placed directly above and parallel to… 2 marks · Numerical
- Q3(b) Calculate force per unit length acting on the wire B due to the current flowing in the wire A. (See Figure 2 below) 2 marks · Numerical
- Q4 Explain Curie’s law for a paramagnetic substance. A rectangular coil having $60$ turns and area of $0\cdot4\text{ m}^2$ is held… 2 marks · Short answer
- Q5 What is motional emf? State any two factors on which it depends. 2 marks · Short answer
- Q6 What is the ratio of the speed of gamma rays to that of radio waves in vacuum? Name an electromagnetic wave which is used in the… 2 marks · Short answer
- Q7 A biconvex lens made of glass (refractive index $1\cdot5$) has two spherical surfaces having radii $20\text{ cm}$ and… 2 marks · Numerical
- Q8 State any two differences between primary rainbow and secondary rainbow. 2 marks · Short answer
- Q9 State de Broglie hypothesis. With reference to photoelectric effect, define threshold wavelength. 2 marks · Short answer
- Q10 Calculate the minimum wavelength of the spectral line present in Balmer series of hydrogen. 2 marks · Numerical
- Q11(a) What is meant by pair annihilation? Write a balanced equation for the same. 2 marks · Short answer
- Q11(b) What is meant by the terms half-life of a radioactive substance and binding energy of a nucleus? 2 marks · Short answer
- Q12 In a communication system, what is meant by modulation? State any two types of modulation. 2 marks · Short answer
- Q13 Obtain an expression for intensity of electric field at a point in end on position, i.e. axial position of an electric dipole. 3 marks · Derivation
- Q14 Deduce an expression for equivalent capacitance C when three capacitors $C_1$, $C_2$ and $C_3$ are connected in parallel. 3 marks · Derivation
- Q15(a) $\varepsilon_1$ and $\varepsilon_2$ are two batteries having emf of $34\text{V}$ and $10\text{V}$ respectively and internal… 3 marks · Numerical
- Q15(b) An electric bulb is marked $200\text{V}, 100\text{W}$. Calculate electrical resistance of its filament. If five such bulbs are… 3 marks · Numerical
- Q16(a) For any prism, prove that: $'n'\text{ or }\mu = \frac{\sin\left(\frac{A + \delta_m}{2}\right)}{\sin\left(\frac{A}{2}\right)}$… 3 marks · Derivation
- Q16(b) When two thin lenses are kept in contact, prove that their combined or effective focal length F is given by… 3 marks · Derivation
- Q17 In Young’s double slit experiment, show graphically how intensity of light varies with distance. In Fraunhofer diffraction, how… 3 marks · Short answer
- Q18 Write one balanced equation each to show: Nuclear fission Nuclear fusion Emission of $\beta^-$ (i.e. a negative beta particle) 3 marks · Short answer
- Q19 With reference to semiconductor devices, define a p-type semiconductor and a Zener diode. What is the use of a Zener diode? 3 marks · Short answer
- Q20(a) An alternating emf of $220\text{V}$ is applied to a circuit containing a resistor R having resistance of $160\,\Omega$ and a… 5 marks · Numerical
- Q20(b) An A.C. generator generating an emf of $\varepsilon = 300 \sin(100\pi t)\text{ V}$ is connected to a series combination of… 5 marks · Numerical
- Q21(a) Draw a labelled ray diagram of an image formed by a refracting telescope with final image formed at infinity. Derive an… 5 marks · Drawing
- Q21(b) Using Huygen’s wave theory, derive Snell’s law of refraction. With the help of an experiment, state how will you identify whether… 5 marks · Short answer
- Q22(a) The forward characteristic curve of a junction diode is shown in Figure 4 below: Calculate the resistance of the diode at: (1)… 5 marks · Short answer
- Q22(b) The arrangement given below represents a logic gate: Copy the following truth table in your answer booklet and complete it… 5 marks · Short answer