Practice Questions

Q21.An LCR circuit as shown in the figure is connected to a voltage source Vac whose frequency can be varied. The frequency, at which the voltage across the resistor is maximum, is : (1) 902 Hz (2) 143 Hz (3) 23 Hz (4) 345 Hz

Q22.A printed page is pressed by a glass of water. The refractive index of the glass and water is 1.5 and 1.33 , respectively. If the thickness of the bottom of glass is 1 cm and depth of water is 5 cm, how much the page will appear to be shifted if viewed from the top ? (1) 1.033 cm (2) 3.581 cm (3) 1.3533 cm (4) 1.90 cm

Q22.The magnetic field in a travelling electromagnetic wave has a peak value of 20 nT. The peak value of electric field strength is : (1) 9 V m−1 (2) 12 V m−1 (3) 3 V m−1 (4) 6 V m−1

Q22.In the circuit shown here, the voltage across E and C are respectively 300 V and 400 V . The voltage E of the ac source is : (1) 400 Volt (2) 500 Volt (3) 100 Volt (4) 700 Volt

Q22.Select the correct statement from the following : (1) Electromagnetic waves cannot travel in vacuum. (2) Electromagnetic waves are longitudinal waves. (3) Electromagnetic waves are produced by charges (4) Electromagnetic waves carry both energy and moving with uniform velocity. momentum as they propagate through space.

Q22.In a series L −C −R circuit, C = 10−11 Farad, L = 10−5 Henry and R = 100Ohm, when a constant D.C. voltage E is applied to the circuit, the capacitor acquires a charge 10−9 C. The D.C. source is replaced by a sinusoidal voltage source in which the peak voltage E0 is equal to the constant D.C. voltage E. At resonance the peak value of the charge acquired by the capacitor will be : JEE Main 2013 (22 Apr Online) JEE Main Previous Year Paper (1) 10−15C (2) 10−6C (3) 10−10C (4) 10−8C

Q23.A plane electromagnetic wave in a non-magnetic dielectric medium is given by →E = →E0 (4 × 10−7x −50t) with distance being in meter and time in seconds. The dielectric constant of the medium is : (1) 2.4 (2) 5.8 (3) 8.2 (4) 4.8

Q23.A thin glass plate of thickness is 2500 λ ( λ is wavelength of light used) and refractive index μ = 1.5 is inserted 3 between one of the slits and the screen in Young's double slit experiment. At a point on the screen equidistant from the slits, the ratio of the intensities before and after the introduction of the glass plate is : (1) 2 : 1 (2) 1 : 4 (3) 4 : 1 (4) 4 : 3

Q23.The graph between angle of deviation (δ) and angle of incidence (i) for a triangular prism is represented by : (1) (2) (3) (4)

Q23.Photons of an electromagnetic radiation has an energy 11keV each. To which region of electromagnetic spectrum does it belong ? (1) X-ray region (2) Ultra violet region (3) Infrared region (4) Visible region

Q23.This question has Statement-1 and Statement-2. Of the four choices given after the Statements, choose the one that best describes the two Statements. Statement 1: Very large size telescopes are reflecting telescopes instead of refracting telescopes. Statement 2: It is easier to provide mechanical support to large size mirrors than large size lenses. JEE Main 2013 (23 Apr Online) JEE Main Previous Year Paper (1) Statement-1 is true and Statement-2 is false. (2) Statement-1 is false and Statement-2 is true. (3) Statement-1 and statement-2 are true and (4) Statements-1 and statement-2 are true and Statement-2 is correct explanation for statement- Statement-2 is not the correct explanation for 1. statement-1.

Q24.The source that illuminates the double − slit in 'double - slit interference experiment' emits two distinct monochromatic waves of wavelength 500 nm and 600 nm , each of them producing its own pattern on the screen. At the central point of the pattern when path difference is zero, maxima of both the patterns coincide and the resulting interference pattern is most distinct at the region of zero path difference. But as one moves out of this central region, the two fringe systems are gradually out of step such that maximum due to on wavelength coincides with the minimum due to the other and the combined fringe system becomes completely indistinct. This may happen when path difference in nm is: (1) 2000 (2) 3000 (3) 1000 (4) 1500

Q24.The focal length of the objective and the eyepiece of a telescope are 50 cm and 5 cm respectively. If the telescope is focussed for distinct vision on a scale distant 2 m from its objective, then its magnifying power will be : (1) −4 (2) −8 (3) +8 (4) −2

Q24.Diameter of a plano - convex lens is 6 cm and thickness at the centre is 3 mm. If the speed of light in the material of lens is 2 × 108 m s−1 , the focal length of the lens is: (1) 30 cm (2) 10 cm (3) 15 cm (4) 20 cm

Q24.Light is incident from a medium into air at two possible angles of incidence (A) 20∘ and (B) 40∘ . In the medium light travels 3.0 cm in 0.2 ns. The ray will : JEE Main 2013 (09 Apr Online) JEE Main Previous Year Paper (1) suffer total internal reflection in both cases (A) (2) suffer total internal reflection in case (B) only and (B) (3) have partial reflection and partial transmission in (4) have 100% transmission in case (A) case (B)

Q24.A light ray falls on a square glass slab as shown in the diagram. The index of refraction of the glass, if total internal reflection is to occur at the vertical face, is equal to : (1) (√2+1) (2) 2 √52 (3) 3 (4) 2 √32

Q25.A ray of light of intensity I is incident on a parallel glass slab at point A as shown in diagram. It undergoes partial reflection and refraction. At each reflection, 25% of incident energy is reflected. The rays AB and A′B′ undergo interference. The ratio of Imax and Imin is : (1) 49 : 1 (2) 7 : 1 (3) 4 : 1 (4) 8 : 1

Q25.This question has Statement-1 and Statements2. Of the four choices given after the Statements, choose the one that best describes the two Statements. Statement-1 : Out of radio waves and microwaves, the radio waves undergo more diffraction. Statement-2 : Radio waves have greater frequency compared to microwaves. (1) Statement-1 is true, Statement-2 is true and (2) Statement-1 is false, Statement-2 is true. Statement-2 is the correct explanation of Statement-1 (3) Statement-1 is true, Statement-2 is false. (4) Statement-1 is true, Statement-2 is true but Statement-2 is not the correct explanation of Statement-1

Q25.A beam of unpolarised light of intensity I0 is passed through a polaroid A and then through another polaroid B which is oriented so that its principle plane makes an angle of 45o relative to that of A . The intensity of the emergent light is: (1) I0 (2) I0 4 8 (3) I0 (4) I02

Q25. n identical waves each of intensity I0 interfere with each other. The ratio of maximum intensities if the interference is (i) coherent and (ii) incoherent is : (1) n2 (2) n1 (3) 1 (4) n n2

Q25.The image of an illuminated square is obtained on a screen with the help of a converging lens. The distance of the square from the lens is 40 cm. The area of the image is 9 times that of the square. The focal length of the lens is : (1) 36 cm (2) 27 cm (3) 60 cm (4) 30 cm

Q26.In an experiment on photoelectric effect, a student plots stopping potential V0 against reciprocal of the wavelength λ of the incident light for two different metals A and B. These are shown in the figure. JEE Main 2013 (25 Apr Online) JEE Main Previous Year Paper Looking at the graphs, you can most appropriately say that: (1) Work function of metal B is greater than that of (2) For light of certain wavelength falling on both metal A metal, maximum kinetic energy of electrons emitted from A will be greater than those emitted from B. (3) Work function of metal A is greater than that of (4) Students data is not correct metal B

Q26.Two coherent point sources S1 and S2 are separated by a small distance d as shown in the figure. The fringes obtained on the screen will be JEE Main 2013 (07 Apr) JEE Main Previous Year Paper (1) semi-circles (2) concentric circles (3) points (4) straight lines

Q26.A person lives in a high-rise building on the bank of a river 50 m wide. Across the river is a well lit tower of height 40 m. When the person, who is at a height of 10 m, looks through a polarizer at an appropriate angle at light of the tower reflecting from the river surface, he notes that intensity of light coming from distance X from his building is the least and this corresponds to the light coming from light bulbs at height ' Y ' on the tower. The values of X and Y are respectively close to (refractive index of water ≃43 ) (1) 25 m, 10 m (2) 13 m, 27 m (3) 22 m, 13 m (4) 17 m, 20 m

Q26.Electrons are accelerated through a potential difference V and protons are accelerated through a potential difference 4 V. The de-Broglie wavelengths are λe and λp for electrons and protons respectively. The ratio of λe is given by: (given me is mass of electron and mp is mass of proton). λp (1) = λp λe = √mpme (2) λpλe √memp (3) = λp λe = 12 √memp (4) λpλe 2√mpme