Physics Questions

An under water swimmer cannot see very clearly even in absolutely clear water because of 1 absorption of light in water 2 scattering of light in water 3 reduction of speed of light in water 4 change in the focal length of eye lens

10 The radius of a planet is twice the radius of earth Both have almost equal average mass densities V and V are escape velocities of the planet and the earth respectively then P a V 1 5 VE c VE 3 Vp b V 2 VE d VE 1 5 Vp Karnataka NEFT 2013

O A thin uniform wire AB of length 1m an unknown resistance X and a resistance of 12 2 are connected by thick conducting strips as shown in figure A battery and a galvanometer with a sliding jockey connected to it are also available Connections are to be made to measure the unknown resistance X using the principle of Wheatstone bridge After appropriate connections are made it is found that no deflection takes place in the galvanometer when the sliding jockey touches the wire at a distance of 60 cm from A Obtain the value of resistance X A X www un C B

The magnitude of acceleration of a point on the wheel s rim at f 1 s whose radius is 2 m anc is spinning with angular velocity to that varies with time as 10 f rad s is 1 40 26 m s 2 40 m s 3 Zero dw at

17 A uniform rod of mass m and length 1 is kept vertical with the lower end clamped It is slightly pushed to let it fall down under gravity Find its angular speed when the rod is passing through its lowest position Neglect any friction at the clamp What will be the linear speed of the free end at this instant Solution E Figure 10 W12

A double convex lens with both faces of the same radius of curvature is manufactured from a glass of refractive index 1 54 If the radius of curvature is 27 cm the focal length of the lens is A 50 cm B 25 cm C 18 cm D 9 cm

7 When a glass capillary tube of radius 0 015 cm is dipped in water the water rises to a height of 15 cm within it Assuming contact angle between water and glass to be 0 the surface tension of water is p 1000 kg m g 9 81 ms 1 0 11 Nm 2 0 7 Nm 1

I have written the standard equation of a straight line for this sum upto y mx 2 c But what to do next 105 In an experiment the resistance of a material is plotted as a function of temperature in some range As shown in the figure it is a straight line In R T One may conclude that T2 T c R T Roe T T ele a R T Roe 1 72 JEE Main 2019 T T2 b R T Roe T T2 d R T Roe

A pure semiconductor crystal has 4 x 1027 atoms m It is doped by 4 ppm concentration of pentavalent atom The number of holes per m will be n 10 6 m 1011 m 3 10 m 3 101 m 3 108 m 3

If the radius of the earth suddenly contracts to one third of its present value then the duration of the day will be approx Mass of earth remains constant 1 24 hours 2 8 hours

A prism is made up of flint glass whose 30 dispersive power is 0 053 Find the angle of dispersion if the mean refractive index of flint glass is 1 68 and the refracting angle of prism is 3 1 20 08 3 0 208 2 10 08 4 0 108 ft A 3

5 The differential equation that describes the behavior of a spring mass apparatus is called the a governing equation b equation of motion c complementary function d steady state solution 6 Simple harmonic motion is also called a free undamped motion b pure resonant motion c forced motion d a and c 7 The period of the equation of motion given by x t 6 sin 4nt is a TT S b 2 s 1 c 47 d 0 5 s S 71 LJ

23 A spherical drop of water has 1 mm radius If the surface tension of water is 75 x 10 N m then difference of pressure between inside and outside of the drop is 1 35 N m 3 140 N m 2 70 N m 4 150 N m

4 Almost independent of h 9 A spring balance reads 200 gF when carrying a lump of lead in air If the lead is now immersed with half of its volume in brine solution what will be the new reading of the spring balance specific gravity of lead and brine are 11 4 and 1 1 respectively 1 190 4 gF 2 180 4 g

a A steady current flows in a metallic conductor of non uniform cross section Which of these quantities is constant along the conductor current current density electric field drift speed

Mechanical Properties of Fluids 199 22 Eight equal drops of water are falling through air with a steady velocity of 10 cm If the drops combine to form a single drop big in size then the terminal velocity of this big drop is

Q No 30 View In English In order that a thin film of oil floating on the surface of water should show colours due to interference the thickness of the oil film should be of the order of 100 10 000 1mm 1 cm 1 2 3 4 Correct Answer 2 Status unattempted Add to Bookmark List 4

2 A constant force acting on a body of mass 3 0 kg changes its speed from 2 0 m s to 3 5 m s in 25 s The direction of motion of the body remains unchanged What is the magnitude and direction of the force

A force F is applied along a rod of transverse cross sectional area A The tangential stress to a section PQ inclined at an angle 0 to transverse section will be maximum for angle 0 in degree is 1 O 3 45 FO FL 0 C P OF 2 30 4 90

5 In a single slit diffraction pattern if the light source is used of less wavelength than previous one then width of the central fringe will be 1 less 2 increased 3 Unchanged 4 None

A diminished image of an object is to be 34 obtained on a screen 1 0 m away from it This can be achieved by approximately placing 1 a convex mirror of suitable focal length 2 a concave mirror of suitable focal length 3 a convex lens of focal length less than 0 5 m 4 a concave lens of suitable focal length

9 10 What is the focal length of a convex lens of focal length 30 cm in contact with a concave lens of focal length 20 cm Is the system a converging or a diverging lens Ignore thickness of the lenses 11 A compound microscope consists of an objective lens of focal length 2 0 cm and an eyepiece of focal length 6 25 cm separated by a distance of 15 cm How far from the objective should an object be

A monkey is sitting on a tree limb The limb exerts two perpendicular forces one of 48 N and another of 20 Find the magnittude of the total force exerted by the limb on the monkey

A long current carrying straight wire having current I 10 ampere is placed at the centre of an another current carrying loop having current I 10 ampere Straight wire is perpendicular to the plane of the loop as shown in the figure The torque in N m acting on the loop about its center is 10x Find the value of x Radius R 1m 60 R R

A hollow sphere is moving with linear velocity and angular velocity as shown in figure The time after which pure rolling starts is Question Type Single Correct Type 1 2 3 A 2v 3 g 4v 7 g 4v 5 g 0 3v R 5v

33 A wave in a string has an amplitude of 2 cm wave travels in the positive direction of x axi a speed of 128 m s and it is noted that 5 con waves fit in 4 m length of the string The equ AIPMT Prelims describing the wave is 1 y 0 02 m sin 15 7x 2010t 2 y 0 02 m sin 15 7x 2010t 002 m sin 785x 10050

A fine in its fine rubber rubber band which in unstretched condition forms a circle of radius r is dropped on a soap film formed over a wire frame When the film inside the band is broken it stretches into a circle of radius nr If the band is cut and used as a single strand to suspend a mass m equilibrium elongation is equal to unstretched length Surface tension of soap film is Question Type Single Correct Type 1 2 S S mg n 1 27nr mg n 1 2nr

L A block of mass M is tied to a spring of force constant k and placed on a smooth horizontal surface The natural length of the spring is L P is a point on the spring at a distance from its fixed end The block is set in oscillations with amplitude A Find the maximum speed of point P on the spring 4 atau yang g k M

A point charge of 40 stat coulomb is placed 2 cm in front of an earthed metallic plane plate of large size Then the force of attraction on the point charge is 1600 dynes 160 dynes 400 dynes Incorrect Correct

A perfectly reflecting solid hemisphere of radius R is placed in the path of a parallel beam of light aperture If the beam carries an intensity I the force exerted by the beam on the hemisphere is O 2TR 1 C TR 1 C 4 R 1 C TR 1

The ratio of angular speed and linear speed of electron in n orbit of hydrogen atom in accordance with Bohr s model wil be O Directly proportional to n Directly proportional to n O Inversely proportional to n O Independent of n

A particle at rest explodes into two fragments of masses m and m m m which move apart with non zero velocities If X and 2 are their de Broglie wavelengths respectively then O A 1 0 11 1 O 1 1 O Data Insufficient

No 37 View In English A small square loop of wire of side I is placed inside a large square loop of wire of side 1 The loop are coplanar and their centres coincide The mutual inductance of the system proportional to 1 3 Correct Answer 2 tatus unattempted VL 12 L 1 12 V

The frequency of ka X ray from an element A of atomic number 20 is The frequency of ka X ray from an element B is 4f Then find the atomic number of element B Answer 00 01 02 03 04 05 06 07 08 09

The driver of a three wheeler moving with a speed of 36 km h sees a child standing in the middle of the road and brings his vehicle to rest in 4s just in time to save the child What is the average retarding force on the vehicle The mass of the three wheeler is 400 kg and the mass of the driver is 65 kg

A heat conducting piston can move freely inside a closed thermally isolated cylinder which contains an ideal gas In equilibrium the piston divides the cylinder in two equal parts the temperature of the gas being To The piston is slowly displaced The adiabatic exponent of the gas is y 2 The temperature of the gas when the volume of one part is n n 2 times than 3 that of the other part is given by T The value of a B is

ON S LAWS A pebble of mass 0 05 kg is thrown vertically upwards Give the magnitude and direction of net force on the pebble a during its upward motion b during its downward motion c at the highest point where it is momentarily at rest Do your answers change if the pebble were thrown at an angle of say 45 with the horizontal direction Ignore air resistance

A series LCR circuit has R 1022 L 0 1 H and C 10 F The circuit is driven by a 100 V rms source with a frequency that can be varied The maximum value of the time averaged power dissipated over a cycle as a function of frequency is A 100 W B 500 W C 700 W D 1000 W

two electric bulbs of the same power but with different marked voltages are connected in series across a power line Their brightness will be O 1 directly proportional to their marked voltages 2 inversely proportional to their marked voltages 3 directly proportional to the squares of their marked voltages 34 4 inversely proportional to the squares of their marked voltages

42 A uniform magnetic confined to a cyclindrical region of radius R The magnetic field is increasing at a constant dB tesla second An electron e m dt placed at the point P on the periphery of the field experiences an acceleration Leut rate of Fart 2011 N LieR leR dB 2m dt 1 2 3 leR dB 2m dt eR dB m dt X X X X X X X X X X XXX X X P X R X towards left x X towards left X towards right X X X 2 P 812 R 16

No 26 View In English A man fires a bullet standing between two cliffs First echo is heard after 3 seconds and second echo is heard after 5 seconds If the velocity of sound is 330 m s then the distance between the cliffs is 1 2 3 Correct Answer 2 1650 m 1320 m 990 m 660 m

A galvanometer has a resistance 5k2 and shows a maximum deflection when a current 20mA flow through it How will you convert this galvanometer into i an ammeter reading up to 10 A current ii a voltmeter reading up to 250 V

A air bubble rises from bottom of a lake to surface If its radius increases by 200 and atmospheric pressure is equal to water coloumn of height H then depth of lake is 1 21 H 3 9 H 2 8 H 4 26 H

the charge density in the beam if the total current is 2 10 A The mobility of electrons in a conductor is defined by the equation vdrift E Find an expression for in terms of conductivity of an Ohmic conductor 1 In a non ohmic conductor electron density varies with electric field as n x E Find how the current

No 35 1 2 3 View In English A 20 kg block is initially at rest A 75 N force is required to set the block in motion After the motion force of 60 N is applied to keep the block moving with constant speed The coefficient of static friction i is correct Answer 4 atus unattempted Complete Question Content 0 6 0 52 0 44 0 375 Close

20 The average translational energy of molecules in a sample oxygen gas at 300 K are 3 15 x 10 21 J The corresponding value at 600 K are nearly A 6 3 x 10 21 J C 12 45 x 10 21 J B 1 5075 x 10 21 J D 3 15 x 10 21 J

A rod of length 4m is leaned against a wall as shown It is released from the position when 8 60 Tr end A of rod remains in contact with the wall and its end B remains in contact with floor as the r slides down The distance covered by the centre of rod by the time it hits the floor is A 4m

21 In Boolean algebra A B Y implies that A sum of A and B is Y B Y exists when A exists or B exists or both A and B exists C Y exists only when A and B are both exist

A diatomic gas undergoes adiabatic compression and its volume reduces to half of initial volume then its final pressure would be if gas initial pressure P 1 2 4P 2 P 2 3 2P 4 3 07 P ic custem undergoes cyclic process

A lift is accelerated upward Will the apparent weight of a person inside the lift increase decrease or remain the same relative to its real weight If the lift is going with uniform speed then