Practice Questions

Q33.An electric bulb is rated 220 volt −100 watt. The power consumed by it when operated on 110 volt will be (1) 50 watt (2) 75 watt (3) 40 watt (4) 25 watt

Q34.Needles N1, N2 and N3 are made of a ferromagnetic, a paramagnetic and a diamagnetic substance respectively. A magnet when brought close to them will (1) attract all three of them (2) attract N1 and N2 strongly but repel N3 (3) attract N1 strongly, N2 weakly and repel N3 (4) attract N1 strongly, but repel N2 and N3 weakly weakly

Q35.In a region, steady and uniform electric and magnetic fields are present. These two fields are parallel to each other. A charged particle is released from rest in this region. The path of the particle will be a (1) circle (2) helix (3) straight line (4) ellipse

Q36.A long solenoid has 200 turns per cm and carries a current i. The magnetic field at its centre is 6.28 × 10−2 Weber /m2 . Another long solenoid has 100 turns per cm and it carries a current i/3. The value of the magnetic field at its centre is (1) 1.05 × 10−4 Weber/m (2) 1.05 × 10−2 Weber /m2 (3) 1.05 × 10−5Weber/m2 (4) 1.05 × 10−3Weber/m2 JEE Main 2006 JEE Main Previous Year Paper

Q37.In an AC generator, a coil with N turns, all of the same area A and total resistance R, rotates with frequency ω in a magnetic field B. The maximum value of emf generated in the coil is " (1) N.A.B. ω (2) N.A.B.R. ω (3) N.A.B (4) N.A.B.R

Q38.The flux linked with a coil at any instant ' t ' is given by ϕ = 10t2 −50t + 250 The induced emf at t = 3 s is (1) 190 V (2) −190 V (3) −10 V (4) 10 V

Q39.In a series resonant LCR circuit, the voltage across R is 100 volts and R = 1kΩ with C = 2μF. The resonant frequency ω is 200rad/s. At resonance the voltage across L is (1) 4 × 10−3 V (2) 2.5 × 10−2 V (3) 40 V (4) 250 V

Q40.An inductor (L = 100mH), a resistor (R = 100Ω) and a battery (E = 100 V) are initially connected in series as shown in the figure. After a long time the battery is disconnected after short circuiting the points A and B. The current in the circuit 1 mm after the circuit is (1) 1 A (2) 1/eA (3) e A (4) 0.1 A

Q41.The rms value of the electric field of the light coming from the Sun is 720 N/C . The average total energy density of the electromagnetic wave is (1) 3.3 × 10−3 J/m3 (2) 4.58 × 10−6 J/m3 (3) 6.37 × 10−9 J/m3 (4) 81.35 × 10−12 J/m3

Q42.The refractive index of glass is 1.520 for red light and 1.525 for blue light. Let D1 and D2 be an of minimum deviation for red and blue light respectively in a prism of this glass. Then (1) D1 > D2 (2) D1 < D2 (3) D1 = D2 (4) D1 can be less than or greater than depending upon the angle of prism

Q43.The time by a photoelectron to come out after the photon strikes is approximately (1) 10−1 s (2) 10−4 s (3) 10−10 s (4) 10−16 s

Q44.The threshold frequency for a metallic surface corresponds to an energy of 6.2eV , and the stopping potential for a radiation incident on this surface 5 V . The incident radiation lies in JEE Main 2006 JEE Main Previous Year Paper (1) X-ray region (2) ultra-violet region (3) infra-red region (4) visible region

Q46.An alpha nucleus of energy 1 mv2 bombards a heavy nuclear target of charge Ze. Then the distance of closest 2 approach for the alpha nucleus will be proportional to (1) 1 (2) v2 Ze (3) 1 (4) 1 m v4

Q48.When 3Li′ nuclei are bombarded by protons, and the resultant nuclei are 4Be8 , the emitted particles will be JEE Main 2006 JEE Main Previous Year Paper (1) neutrons (2) alpha particles (3) beta particles (4) gamma photons

Q60.In the transformation of 238 92 U to 23492 U , if one emission is an α-particle, what should be the other emission(s)? (1) Two β− (2) Two β− and one β+ (3) One β− and one γ (4) One β+ and one β−

Q1. A particle is moving eastwards with a velocity of 5 m/s in 10 seconds the velocity changes to 5 m/s northwards. The average acceleration in this time is (1) 1 m/s2 towards north-east (2) 21 m/s2 towards north. √2 (3) zero (4) 1 m/s2 towards north-west √2

Q2. Out of the following pair, which one does NOT have identical dimensions is (1) angular momentum and Planck's constant (2) impulse and momentum (3) moment of inertia and moment of a force (4) work and torque

Q3. The relation between time t and distance x is t = ax2 + bx where a and b are constants. The acceleration is (1) −2abv2 (2) 2bv3 (3) −2av3 (4) 2av2

Q4. A car starting from rest accelerates at the rate f through a distance S , then continues at constant speed for time t and then decelerates at the rate f/2 to come to rest. If the total distance traversed is 15 S, then (1) S = ft (2) S = 1/6ft2 (3) S = 1/2ft2 (4) None of these

Q5. A parachutist after bailing out falls 50 m without friction. When parachute opens, it decelerates at 2 m/s2 . He reaches the ground with a speed of 3 m/s. At what height, did he bail out? (1) 91 m (2) 182 m (3) 293 m (4) 111 m

Q6. Two points A and B move from rest along a straight line with constant acceleration f and f ' respectively. If A takes m sec. more than B and describes ' n ' units more than B in acquiring the same speed then (1) (f −f ′)m2 = ff ′n (2) (f + f ′)m2 = ff ′n (3) 2 1 (f + f ′)m = ff ′n2 (4) (f ′ −f)n = 21 ff ′m2

Q7. A and B are two like parallel forces. A couple of moment H lies in the plane of A and B and is contained with them. The resultant of A and B after combining is displaced through a distance (1) 2H (2) H A−B A+B (3) H (4) H 2(A+B) A−B

Q8. A projectile can have the same range R for two angles of projection. If t1 and t2 be the times of flights in the two cases, then the product of the two time of flights is proportional to (1) R2 (2) 1/R2 (3) 1/R (4) R

Q9. A particle is projected from a point O with velocity u at an angle of 60∘ with the horizontal. When it is moving in a direction at right angles to its direction at O , its velocity then is given by (1) u (2) u 3 2 (3) 2u (4) u 3 √3

Q10.A smooth block is released at rest on a 45∘ incline and then slides a distance d. The time taken to slide is n times as much to slide on rough incline than on a smooth incline. The coefficient of friction is JEE Main 2005 JEE Main Previous Year Paper 1 − n2 (1) μk = 1 − n21 (2) μk = √1 1 − n2 (3) μs = 1 − n21 (4) μs = √1