Practice Questions

Q10.Match the thermodynamics processes taking place in a system with the correct conditions. In the table : ΔQ is the heat supplied, ΔW is the work done and ΔU is change in internal energy of the system. Process Condition (I) Adiabatic (A) ΔW = 0 (II) Isothermal (B) ΔQ = 0 (III) Isochoric (C) ΔU ≠0, ΔW ≠0, ΔQ ≠0 (IV) Isobaric (D) ΔU = 0 (1) (I) - (A), (II) - (B), (III) - (D), (IV) - (D) (2) (I) - (B), (II) - (A), (III) - (D), (IV) - (C) (3) (I) - (A), (II) - (A), (III) - (B), (IV) - (C) (4) (I) - (B), (II) - (D), (III) - (A), (IV) - (C)

Q10.Ten charges are placed on the circumference of a circle of radius R with constant angular separation between successive charges. Alternate charges 1, 3, 5, 7, 9 have charge (+q) each, while 2, 4, 6, 8, 10 have charge (–q) each. The potential V and the electric field E at the centre of the circle are respectively : (Take V = 0 at infinity) (1) V = 10q ; E = 0 (2) V = 0, E = 10q 4πϵ0R 4πϵ0R2 (3) V = 0; E = 0 (4) V = 10q ; E = 10q 4πϵ0R 4πϵ0R2

Q10.A gas mixture consists of 3 moles of oxygen and 5 moles of argon at temperature T . Assuming the gases to be ideal and the oxygen bond to be rigid, the total internal energy (in units of RT ) of the mixutre is : (1) 15 (2) 13 (3) 20 (4) 11

Q11.A potentiometer wire PQ of 1m length is connected to a standard cell E1 . Another cell E2 of emf 1. 02 V is connected with a resistance ' r' and switch S (as shown in figure). With switch S open, the null position is obtained at a distance of 49 cm from Q. The potential gradient in the potentiometer wire is : (1) 0. 02 V/ cm (2) 0. 01 V/ cm (3) 0. 03 V/ cm (4) 0. 04 V/ cm JEE Main 2020 (02 Sep Shift 2) JEE Main Previous Year Paper

Q12.Consider the force F on a charge ' q' due to a uniformly charged spherical shell of radius R carrying charge Q distributed uniformly over it. Which one of the following statements is true for F , if ' q' is placed at distance r from the centre of the shell? (1) F = 1 Qq for r < R (2) 1 qQ > F > 0 for r < R 4π∈0 R2 4π∈0 R2 (3) F = 1 Qq for r > R (4) F = 1 Qq for all r 4π∈0 r2 4π∈0 r2 JEE Main 2020 (06 Sep Shift 2) JEE Main Previous Year Paper

Q12.Consider four conducing materials copper, tungsten, mercury and aluminum with resistivity ρC, ρT, ρM and ρA respectively. Then : (1) ρC > ρA > ρT (2) ρM > ρA > ρC (3) ρA > ρT > ρC (4) ρA > ρM > ρC JEE Main 2020 (02 Sep Shift 1) JEE Main Previous Year Paper

Q12.In the figure, potential difference between A and B is: (1) 10 V (2) 5 V (3) 15 V (4) 0 V

Q13.A galvanometer is used in laboratory for detecting the null point in electrical experiments. If, on passing a current of 6mA it produces a deflection of 2° , its figure of merit is close to : (1) 333° A/div (2) 6 × 10−3A/ div (3) 666° A/div. (4) 3 × 10−3A/ div JEE Main 2020 (05 Sep Shift 2) JEE Main Previous Year Paper

Q13. The figure gives experimentally measured B vs. H variation in a ferromagnetic material. The retentivity, coercivity and saturation, respectively, of the material are: JEE Main 2020 (07 Jan Shift 2) JEE Main Previous Year Paper (1) 1.5T, 50A/m and 1.0T (2) 1.5T, 50A/m and 1.0T (3) 150A/m, 1.0T and 1.5T (4) 1.0T, 50A/m and 1.5T → ˆi+ˆj

Q13.A galvanometer having a coil resistance 100 Ω gives a full scale deflection when a current of 1mA is passed through it. What is the value of the resistance which can convert this galvanometer into a voltmeter given full scale deflection for a potential difference of 10V? (1) 10kΩ (2) 8.9 kΩ (3) 7.9 kΩ (4) 9.9 kΩ

Q14.An AC circuit has R = 100Ω, C = 2μF and L = 80 mH, connected in series. The quality factor of the circuit is : (1) 2 (2) 0.5 (3) 20 (4) 400

Q14.A small point mass carrying some positive charge on it, is released from the edge of a table. There is a uniform electric field in this region in the horizontal direction. Which of the following options then correctly describe the trajectory of the mass ? (Curves are drawn schematically and are not to scale) (1) (2) (3) (4)

Q14.A circuit to verify Ohm's law uses ammeter and voltmeter in series or parallel connected corrected correctly to the resistor. In the circuit : (1) ammeter is always used in parallel and voltmeter (2) Both ammeter and voltmeter must be connected is series in parallel (3) ammeter is always connected in series and (4) Both ammeter and voltmeter must be connected voltmeter in parallel in series

Q15.An electrical power line, having a total resistance of 2Ω, delivers 1 kW at 220 V. The efficiency of the transmission line is approximately : (1) 72% (2) 91% (3) 85% (4) 96%

Q16.Choose the correct option relating wavelengths of different parts of electromagnetic wave spectrum: (1) λvisible < λmicro waves < λradio waves < λx-rays (2) λradio waves > λmicro waves > λvisible > λx-rays (3) λx-rays < λmicro waves < λradio waves < λvisible (4) λvisible > λx-rays > λradio waves > λmicro waves

Q16.In a Young's double slit experiment, light of 500 nm is used to produce and interference pattern. When the distance between the slits is 0. 05 mm, the angular width (in degree) of the fringes formed on the distance screen is close to : (1) 0. 17° (2) 0. 57° (3) 1. 7° (4) 0. 07°

Q17.The correct match between the entries in column I and column II are : I II Radiation Wavelength a Microwave i 100 m b Gamma rays ii 10−15m c A.M. radio iii 10−10m JEE Main 2020 (05 Sep Shift 2) JEE Main Previous Year Paper d X–rays iv 10−3m (1) (a)–(ii), (b) – (i), (c) – (iv), (d) – (iii) (2) (a)–(i), (b) – (iii), (c) – (iv), (d) – (ii) (3) (a)–(iii), (b) – (ii), (c) – (i), (d) – (iv) (4) (a)–(iv), (b) – (ii), (c) – (i), (d) – (iii)

Q17.A vessel of depth 2h is half filled with a liquid of refractive index 2√2 and the upper half with another liquid of refractive index √2 . The liquids are immiscible. The apparent depth of the inner surface of the bottom of the vessel will be JEE Main 2020 (09 Jan Shift 1) JEE Main Previous Year Paper (1) h (2) h √2 2(√2+1) (3) h (4) 3√2h 3√2 4

Q17.The magnifying power of a telescope with tube length 60cm is 5. What is the focal length of its eye piece? (1) 20cm (2) 40cm (3) 30cm (4) 10cm

Q17.An electron, a doubly ionized helium ion ( He++ ) and proton are having the same kinetic energy. The relation between their respective de-Broglie wavelength λe*λHe++ and λp is : (1) λe > λHe++ > λp (2) λe < λHe++ == λp (3) λe > λp > λHe++ (4) λe < λp < λHe++

Q18.In a Young’s double slit experiment, the separation between the slits is 0.15mm . In the experiment, a source of light of wavelength 589nm is used and the interference pattern is observed on a screen kept 1.5m away. The separation between the successive bright fringes on the screen is: (1) 6.9mm (2) 3.9mm (3) 5.9mm (4) 4.9mm

Q18.In a photoelectric effect experiment, the graph of stopping potential V versus reciprocal of wavelength obtained is shown in the figure. As the intensity of incident radiation is increased : JEE Main 2020 (04 Sep Shift 2) JEE Main Previous Year Paper (1) Straight line shifts to right (2) Slope of the straight line get more steep (3) Straight line shifts to left (4) Graph does not change

Q18.Interference fringes are observed on a screen by illuminating two thin slits 1 mm apart with a light source (λ = 632. 8 nm). The distance between the screen and the slits is 100 cm. If a bright fringe is observed on a screen at distance of 1. 27 mm from the central bright fringe, then the path difference between the waves, which are reaching this point from the slits is close to : (1) 1. 27μm (2) 2 . 87 nm (3) 2 nm (4) 2. 05 μm

Q18.In a double – slit experiment, at a certain point on the screen the path difference between the two interfering waves is 1 8 th of a wavelength. The ratio of the intensity of light at that point to that at the center of a bright fringe is: (1) 0.853 (2) 0.672 (3) 0.568 (4) 0.760 →

Q19.A particle moving with kinetic energy E has de Broglie wavelength λ . If energy ΔE is added to its energy, the wavelength become λ . Value of ΔE, is: 2 (1) E (2) 4E (3) 3E (4) 2E