Practice Questions

Q65.A Young’s double slit experiment uses a monochromatic source. The shape of the interference fringes formed on a screen is (1) hyperbola (2) circle (3) straight line (4) parabola JEE Main 2005 JEE Main Previous Year Paper

Q66.Two point white dots are 1 mm apart on a black paper. They are viewed by eye of pupil diameter 3 mm . Approximately, what is the maximum distance at which these dots can be resolved by the eye? [ Take wavelength of light = 500 nm ] (1) 5 m (2) 1 m (3) 6 m (4) 3 m

Q67.When an unpolarized light of intensity I0 is incident on a polarizing sheet, the intensity of the light which does not get transmitted is (1) 1 2 I0 (2) 41 I0 (3) zero (4) I0

Q68.If I0 is the intensity of the principal maximum in the single slit diffraction pattern, then what will be its intensity when the slit width is doubled? (1) 2I0 (2) 4I0 (3) I0 (4) I0/2

Q69.A photocell is illuminated by a small bright source placed 1 m away. When the same source of light is placed 1 m away, the number of electrons emitted by photo cathode would 2 (1) decrease by a factor of 4 (2) increase by a factor of 4 (3) decrease by a factor of 2 (4) increase by a factor of 2

Q70.If the kinetic energy of a free electron doubles. Its deBroglie wavelength changes by the factor (1) 1 (2) 2 2 (3) 1 (4) √2 √2

Q71.The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy ? (1) III (2) IV (3) I (4) II

Q72.The intensity of gamma radiation from a given source is I. On passing through 36 mm of lead, it is reduced to I . The thickness of lead which will reduce the intensity to I will be 8 2 (1) 6 mm (2) 9 mm (3) 18 mm (4) 12 mm

Q73.Starting with a sample of pure 66Cu, 7/8 of it decays into Zn in 15 minutes. The corresponding half-life is (1) 10 minutes (2) 15 minutes (3) 5 minutes (4) 7 12 minutes

Q74.If radius of 2713Al nucleus is estimated to be 3.6 Fermi then the radius 12552 Te nucleus be nearly JEE Main 2005 JEE Main Previous Year Paper (1) 6 fermi (2) 8 fermi (3) 4 fermi (4) 5 fermi

Q75.A nuclear transformation is denoted by X(n, α)73Li. Which of the following is the nucleus of element X ? (1) 12C6 (2) 105 B (3) 95 B (4) 114 Be

Q76.The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than 2480 nm is incident on it. The band gap in (eV) for the semiconductor is (1) 1.1eV (2) 2.5eV (3) 0.5eV (4) 0.7eV

Q77.In a common base amplifier, the phase difference between the input signal voltage and output voltage is (1) π (2) π 4 (3) 0 (4) π2

Q78.In a full wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be (1) 50 Hz (2) 25 Hz (3) 100 Hz (4) 70.7 Hz

Q86.The photon of hard gamma radiation knocks a proton out of 2412Mg nucleus to form (1) the isotope of parent nucleus (2) the isobar of parent nucleus (3) the nuclide 2311Na (4) the isobar of 2311Na

Q1. If →A × →B = →B × →A, then the angle between A and B is (1) π (2) π/3 (3) π/2 (4) π/4

Q2. Which one of the following represents the correct dimensions of the coefficient of viscosity? (1) ML−1 T−2 (2) MLT−1 (3) ML−1 T−1 (4) ML−2 T−2

Q3. A ball is released from the top of a tower of height h metres. It takes T seconds to reach the ground. What is the position of the ball in T/3 seconds? (1) h/9 metres from the ground (2) 7 h/9 metres from the ground (3) 8 h/9 metres from the ground (4) 17 h/18 metres from the ground.

Q4. An automobile travelling with speed of 60 km/h, can brake to stop within a distance of 20 cm. If the car is going twice as fast, i.e 120 km/h, the stopping distance will be (1) 20 m (2) 40 m (3) 60 m (4) 80 m

Q5. A ball is thrown from a point with a speed v0 at an angle of projection θ. From the same point and at the same instant person starts running with a constant speed v0/2 to catch the ball. Will the person be able to catch the ball? If yes, what should be the angle of projection? (1) yes, 60∘ (2) yes, 30∘ (3) no (4) yes, 45∘

Q6. A projectile can have the same range R for two angles of projection. If T1 and T2 be the time of flights in the two cases, then the product of the two time of flights is directly proportional to (1) 1/R2 (2) 1/R (3) R (4) R2

Q7. If t1 and t2 are the times of flight of two particles having the same initial velocity u and range R on the horizontal, then t21 + t22 is equal to (1) u2 (2) 4u2 g g2 (3) u2 (4) 1 2g

Q8. A machine gun fires a bullet of mass 40 g with a velocity 1200 ms−1 . The man holding it can exert a maximum force of 144 N on the gun. How many bullets can he fire per second at the most? (1) one (2) four (3) two (4) three JEE Main 2004 JEE Main Previous Year Paper

Q9. Two masses m1 = 5 kg and m2 = 4.8 kg tied to a string are hanging over a light frictionless pulley. What is the acceleration of the masses when lift free to move (g = 9.8 m/s2) (1) 0.2 m/s2 (2) 9.8 m/s2 (3) 5 m/s2 (4) 4.8 m/s2

Q10.A block rests on a rough inclined plane making an angle of 30∘ with the horizontal. The coefficient of static friction between the block and the plane is 0.8 . If the frictional force on the block is 10 N , the mass of the block (in kg ) is (take g = 10 m/s2 ) (1) 2.0 (2) 4.0 (3) 1.6 (4) 2.5