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ee a UCSKM PUBLICSCHOOL UNIT TEST I_ (2026-27) au SUBJECT: PHYSICS (SET A) | CLASS: XII “ M.M:50 Time: 90 mins. Date:08/05/2026 Name General Instructions: 1. There are 23 questions in all. All questions are compulsory. This question paper has five sections: Section A, Section B, Section C, Section D and Section E i Section A contains 10 questions, 8 MCQ and 2 Assertion Reasoning based of 1 mark each, Section B contains 4 questions of two marks each, Section C contains 6 questions of three marks each, Section D contains ONE case study-based questions of four marks and Section E contains 2 long questions of five marks each. 4. You may use the following values of physical constants where ever necessary ic=3 x 10°m/s me = 9.1 x10! kg iii, mp = 1.7 x10 iv.e=1.6x 107°C vi. h= 6.63 x10°4Js 0 = 8.854 x10"? viii. Avogadro's number = 6.023 X 10% per gram mole, ww SECTION-A (1X10=10) 1. The amount of work done in moving a charge from one point to another along an equipotential line or surface charge is a. Zero b. Infinity c. One d. Two Z) A copper sphere of mass 2 gm contains about 2 x 102 atoms. The charge on the nucleus of each atom is 29e. The fraction of electrons removed from the sphere of 2j1c? a Dx NOY b. 1.19x10" ©, LAB d.2.16x10"!! 3. A spherical conductors of radius 2 cm are uniformly charged with 3 nC. What is the electric field at a distance of 3 cm from the centre of the sphere? a. 3x10° V m7! b.3 Vm! ¢. 3x10' V m1 d. 3x10" V m! 4. A square sheet of side a is lying parallel to XY-plane at z=a. The electric field in the region is E: The electric flux through the sheet is 2, Ge b. 1/Ba%c ¢. 1Bate d.0 5. A capacitor is charged by a battery. The battery is removed and another identical uncharged capacitor is connected in parallel. The total electrostatic energy of resulting system a. increases by a factor of 4. b. decreases by a factor of 2. c. remains the same.: d. increases by a factor of 2. 6. A hollow metal sphere of radius 5 cm is charged so that the potential on its surface is 10 V. The potential at the centre of the sphere is a.0V b. 10 V c. Same as at point 5 cm away from the surface d. Same as at point 25 em away from the surface 7. An clectric dipole consisting of charges + and —q separated by a distance Z is in stable equilibrium ina uniform electric field Z. The electrostatic potential energy of the dipole is 2 GULIE) b. zero ¢.-qLE d, -2qLE 8. A capacitor stores 0.24 coulombs charge at 10 volt. Its capacitance is a. 0.024 F Dee i OSes d. 0.8 F Assertion-Reason: : : : (a) Both Assertion (A) and Reason (R)are true and Reason (R ) is the correct explanation of Assertion(A) (b) Both Assertion (A) and Reason (R)are true and Reason (R ) is not the correct explanation ofAssertion(A) eason (R) js false x surface. +) Assertion (A) js true, but Re iS & ‘Assertion (A) js false, but Reason(RIISTUe pole otis pute 9, Assertion: All the charge jn aconductot gels distributed onW he Pay minimum. : Reason: Ina dynamic system, charges UY to keep their potenta e > Bie Ghat Ri tr 10. Assertion: Electric field is always normal to equipotential surfaces ane along order of potential. : a neat Reason: Negative gradient of electric potential js electric fiele- SECTION-B @Xx4=8) 15cm) (0, 0 nt of the sys ics. 2.510 7€ locate tric dat points A: dipole mome nciple in electrostati Aas tem? tively. What are the tota 11, State and prove Superposition pri 12. A system has two charges da and B: (0, 0, + 15 em), respec’ I charge and elec! yare of side 10 cm, as shown in fig. OR A poi oe A aus oc +10 pC isa distance 5 cm directly above the center ofasq i he magnitude of the electric flux through the square? (Hint: Think of the square as one face ofa cube with edge 10 cm.) aan 5 cu’ 13. Consider two i Te) ge: c 0 identical poi 0) and (a, ¢ @ist g int charges located at poi i : DOME Ones points (0. (ii) Is there P th - a ik a ig them at which re ee oe zero % ae th ine joming them at which the electric eertel i 3 ify fe r lal is Zero: Justi your ar iswers 14. The figure shows a network five ca) ce} iS! of fiv pacitors t RE ee TV citors connected to a 10V battery. Calculate th i y- e the charge acquired raw the equipotential s se) ing to a in zZ-aire ices Corresponding uniform electric field in the z-d Di tential surfa id t | the ‘irection A conducting slab of thickness 1 is i econo. ipacitor, separated by a distance at S uced without touching between the plat (3X6=18) ‘ d). Derive an expression for the cap: i a oa plate ce of the capacitor nooo! vex pass harmlessly around the outside of the cage, | (i) Which of the following material can be used to make a Faraday cage? (a) Plastic (b) Glass : (c) Copper + (d) Wood Gi) Example ofa real-world Paraday cage is Wi) ear (b) plastic box (c) lightning rod (d) metal rod (i) What is the electrical force inside a Faraday cage when itis struck by lightning? (a) The same as the lightning (b) Half that of the lightning (c) Zero « (d) A quarter of the lightning (iy) An isolated point charge +q ts placed inside the Faraday cage. Its surface must have charge equal to (a) Zero (b) +q (c)=q. (d) +2q OR (y) A point charge of 2C is placed at centre of Faraday cage in the shape of cube with surface of 9 cm edge. The number of electric field lines passing through the cube normally will be (a) 1.9X10° Nm? /C entering the surface (b) 1.9X10° Nin? /C leaving the surface (c) 2.0X10° Nm? /C leaving the surface (d) 2.0X10° Nm? /C entering the surface SECTION-E, (5X2=10) Be: pee an expression for the electric potential due to a dipole of charges -q and +q of dipole length 2a at any point. - (#) Calculate the electric potential at a point due to a charge of 4x 10°” C located 9 cm away. Also obtain the work done in bringing a charge of 2x 10° C from infinity to that point. OR (i) Anon conducting slab of thickness ¢ is introduced without touching between the plates of a parallel plate capacitor, separated by a distance d ( < d). Derive an expression for the capacitance of the capacitor. : (ii) Calculate the equivalent capacitance between the points A and B of the circuit given below. Ifa battery of emf 10 V is connected between the points A and B, calculate the total charge in the cireuit. a ie 4t 1k 10 pF if 20 uF 50 uF Cy 0 legame Surf | 10uF pee [08 | i u G CG hows mathematically that for any point outside the shell, the field due to a uniformly tire charge on the shell, is concentrated at the centre. the shell to be m 4 
