Practice Questions

Q65.To get three images of a single object, one should have two plane mirrors at an angle of (1) 60∘ (2) 90∘ (3) 120∘ (4) 30∘

Q66.To demonstrate the phenomenon of interference, we require two sources which emit radiation (1) of nearly the same frequency (2) of the same frequency (3) of different wavelengths (4) of the same frequency and having a definite phase relationship

Q71.Which of the following radiations has the least wavelength? (1) γ -rays (2) β-rays (3) α-rays (4) X-rays

Q78.Consider telecommunication through optical fibres. Which of the following statements is not true? (1) Optical fibres can be of graded refractive index (2) Optical fibres are subjective to electromagnetic interference from outside (3) Optical fibres have extremely low transmission (4) Optical fibres may have homogeneous core with loss a suitable cladding.

Q85.The radionucleide 23490 Th undergoes two successive β-decays followed by one α-decay. The atomic number and the mass number respectively of the resulting radionucleide are (1) 94 and 230 (2) 90 and 230 (3) 92 and 230 (4) 92 and 234

Q92.The internal energy change when a system goes from state A to B is 40 kJ/mole. If the system goes from A to B by a reversible path and retums to state A by an irreversible path what would be the net change in internalenergy? (1) > 40 kJ (2) < 40 kJ (3) Zero (4) 40 kJ

Q2. Identify the pair whose dimensions are equal (1) torque and work (2) stress and energy (3) force and stress (4) force and work

Q5. Speeds of two identical cars are u and 4u at the specific instant. The ratio of the respective distances in which the two cars are stopped from that instant is (1) 1 : 1 (2) 1 : 4 (3) 1 : 8 (4) 1 : 16

Q13.A spring of force constant 800 N/m has an extension of 5 cm. The work done is extending it from 5 cm to 15 cm is (1) 16 J option 1 goes here (2) 8 J (3) 32 J (4) 24 J

Q15.Two identical particles move towards each other with velocity 2v and v respectively. The velocity of centre of mass is (1) v (2) v/3 (3) v/2 (4) zero JEE Main 2002 JEE Main Previous Year Paper

Q17.A solid sphere, a hallow sphere and a ring are released from top of an inclined plane (frictionless) so that they slide down the plane. Then maximum acceleration down the plane is for (no rolling) (1) solid sphere (2) hollow sphere (3) ring (4) all same

Q18.Moment of inertia of a circular wire of mass M and radius R about its diameter is (1) MR2/2 (2) MR2 (3) 2MR2 (4) MR2/4

Q19.A particle of mass m moves along line PC with velocity v as shown. What is the angular momentum of the particle about P? (1) mvL (2) mvl (3) mvr (4) zero

Q21.If suddenly the gravitational force of attraction between Earth and a satellite revolving around it becomes zero, then the satellite will (1) continue to move in its orbit with same velocity (2) move tangentially to the originally orbit in the same velocity (3) become stationary in its orbit (4) move towards the earth.

Q23.The escape velocity of a body depends upon mass as (1) m0 (2) m1 (3) m2 (4) m3 JEE Main 2002 JEE Main Previous Year Paper

Q24.A cylinder of height 20 m is completely filled with water. The velocity of efflux of water (in ms−1 ) through a small hole on the side wall of the cylinder near its bottom is (1) 10 (2) 20 (3) 25.5 (4) 5

Q25.Heat given to a body which raises its temperature by 1∘C is (1) water equivalent (2) thermal capacity (3) specific heat (4) temperature gradient

Q26.Which of the following is more closed to a black body? (1) black board paint (2) green leaves (3) black holes (4) red roses

Q28.If θi , is the inversion temperature, θn is the neutral temperature, θc is the temperature of the cold junction, then (1) θi + θc = θn (2) θi −θc = 2θn (3) θi+θc 2 = θn (4) θc −θi = 2θn

Q29.Which statement is incorrect? (1) all reversible cycles have same efficiency (2) reversible cycle has more efficiency than an irreversible one (3) Carnot cycle is a reversible one (4) Carnot cycle has the maximum efficiency in all cycles

Q30.Even Carnot engine cannot give 100% efficiency because we cannot (1) prevent radiation (2) find ideal sources (3) reach absolute zero temperature (4) eliminate friction

Q31.Cooking gas containers are kept in a lorry moving with uniform speed. The temperature of the gas molecules inside will (1) increase (2) decrease (3) remain same (4) decrease for some, while increase for others

Q35.If a spring has time period T, and is cut into n equal parts, then the time period of each part will be (1) T√n (2) T/√n (3) nT (4) T

Q38.Tube A has both ends open while tube B has one end closed, otherwise they are identical. The ratio of fundamental frequency of tube A and B is (1) 1 : 2 (2) 1 : 4 (3) 2 : 1 (4) 4 : 1

Q39.A tuning fork arrangement (pair) produces 4 beats / sec with one fork of frequency 288cps. A little wax is placed on the unknown fork and it then produces 2 beats /sec. The frequency of the unknown fork is (1) 286 cps (2) 292 cps (3) 294 cps (4) 288 cps