Physics Questions

1 1 20 min A body cools from 60 C to 40 C in 10 minutes If the room temperature is 10 C and assuming Newton s cooling law holds good find the time taken to cools from 40 C to 20 C Question Type Single Correct Type 2 30 min 3 40 min English 4 50 min Review

12 The south pole of a bar magnet is rapidly moved towards one face let us say A of a coil Which of the following statements correctly depicts the phenomenon taking place No induced emf is developed The face A of the coil behaves like a south pole The face A of the coil behaves like north pole d The face A of the coil acquires zero potential

27 Following figure shows the variation of velocity with time for an object Determine the displacement of the object during the 16 seconds Also find the acceleration of the object during the time interval 10 to 14 seconds v m s 10 t s 2 4 6 8 10 12 14

Body of mass M is kept on a rough horizontal surface having coefficient of friction u Person is trying to pull the body by applying an external force horizontally but the body is not moving The force by the surface on A is F then A F Mg 2 C Mg F Mg 1 B F Mg D Mg F Mg 1 2 efficient of friction between the block and

figure shown car A is travelling due north and car B is traveling due east They collide and stick to each other Here 1 2 3 4 ossible direction of motion of cars Which is most likely 1 2 4 W E

6 The charge flowing in a conductor varies with time as Q at bt2 Then the curre decreases linearly with time reaches a maximum and then decreases falls to zero after a time period t 3a 2b changes at a rate 2b

11 Two electric bulbs A and B are designed for the same voltage Their power ratings are PA 500W and PB 400W respectively with PA PB If they are joined in series across a 300 Volt supply A will draw more power than B B will draw more power than A the ratio of powers drawn by them will depend on V A and B will draw the same nowor

The frequency of tuning fork in resonance tube experiment is 500 Hz The first resonance occured at vibrating length of air column of 17 cm The inner diameter of tube is 3 cm hence velocity of sound in air is CO3 O 35800 m s O 34000 cm s O 34000 m s O 358 m s

A ladder of mass m and length I stands against a frictionless wall with its feet on a frictionless floor If it is let go at an initial angle 80 60 then the angle 0 at which the ladder loses contact with the wall is given as sin 1 N find N 1

In colder regions like the poles two identical open containers one fille with hot water and the other filled with cold water if left exposed t atmosphere it is observed that usually the hot water freezes earlie than the cold water I The hot water has more heat to lose II The hot water initially loses heat at a faster rate III More evaporation causes more heat loss in hot water Which of the above reasons can be responsible for this effect a Reason II b Reason III c Reasons II and III d All the above reasons

39 Switch is in position A for a long time It is suddenly switched to the side B Mass of rod is m and lengt 1 Maximum speed of rod will be 1 F E L R A B 000000 L I m I m 2 7 R E m OB

zero XO A block accelerates down a slope as shown in the figure The upper portion of the slope is smooth and lower portion is rough On the lower portion d A Rough Smooth 0 i the speed of the block may decrease or remain same ii the acceleration of block reduces iii the forces are balanced Sonsti Which of the following is are correct a Only i c ii and iii b i and ii d i ii and iii

Find current i at time t 0 and time t in the following circuits R a c L 000000 R 3R 6R E 3R www R 000000 000000 L wwww 3R R r d www 2R R www www 2R www L www R oundations Education Svices Limited

A particle is rotated in a vertical circle by connecting it to a string of length and keeping the other end of the string fixed The minimum speed of the particle when the string is horizontal for which the particle will complete the circle is A ge C 3gl B 2gl D 5gl

In the circuit shown in figure charge varies with time as q q 1 e IRC The correct option about the rate of heat produced in resistance R with time is A B G C E R E R e E e E D t RC 2t RC t RC R www

2 A metal rod of length 10 cm and a rectangular cross section of 1 cm x cm is connected to a battery across opposite faces The resistance will be a maximum when the battery is connected across 1cm x1 2 cm faces b maximum when the battery is connected across 10cm x1 cm faces c maximum when the battery is connected across 10 cm x1 2 cm faces d same irrespective of three faces

Q The ends of a rod of length L and mass m attached to identical spring rod free to rotate about centre O The rod s depressed slightly at A and released Time period of osci lation is 119 110mm 2115 min 315 min 4 V min 27 The ends of a rod of length I and mass mare attached to two identical springs as shown in the figure The rod is free to rotate about its centre O The rod is depressed slightly at end A and released The time period of the oscillation is 1

8 In the given diagram the reading of the ammeter is when the internal resistance of the battery is zero 402 1 40 29 A Hint PD across 502 is 10 V www 2 10 9 A www 502 3 5 3 A T10 V 4 2 A

The path difference between two waves arriving at a point simultaneously is 38 5 times wavelength of light The CO2 Opoint will be dark Opoint will be bright O point will be sometimes dark sometimes bright nature of point can not be predicted

An electric spark jumps along a straight line of length L 10 m emitting a pulse of sound that travels radially outward from the spark The spark is said to be a line source of sound The power of this acoustic emission is P 1 6 x 104 W a What is the intensity I of the sound when it reaches a distance r 12 m from the spark b At what time rate PA is sound energy intercepted by an acoustic detector of area Ad 2 0cm aimed at the spark and located a distance r 12 m from the spark

A given object takes n times more time to slide down a 45 rough inclined plane than the time taken to slide down the similar but a smooth inclined plane The coefficient of kinetic friction between the object and the rough inclined plane is A B 1 C 1 1 n 1 1 2 n 5 2 0 D 1 n 1 1 n

One conducting U tube can slide inside another as shown in figure maintaining electrical contacts between the tubes The magnetic field B is perpendicular to the plane of the figure If each tube moves towards the other at a constant speed v then the emf induced in the circuit in terms of B I and v where I is the width of each tube will be a Bl v b Bly c zero D d 2 BL

1 Capacitance of a parallel plate capacitor can be increased by a increasing the distance between the plates b decreasing the distance between the plates c decreasing the area of plates d increasing the thickness of the plates

10 Two point charges 50 C and 25 C are 20 cm apart as shown The work done to displace 25 C charge from B point to C will be A 50 C 20 cm 1 11 25 J 3 9 29 J 190 Medical 15 cm 25 C B 2 16 45 J 4 3 25 J

The quantity of electricity required to reduce 12 3 g of nitro benzene to aniline assuming 50 current effeciency is in 1 115800 C 3 231600 C Abne 2 57900 C 4 28950 C

A particle of mass 6kg moving with a velocity of 10 m s collides with another particle of 3kg at rest initially If the coefficient of restitution is e 1 2 calculate loss in kinetic energy 1 75 J 3 125 J 2 100 J 4 200 J

During the electrolysis of water 4 mol of electrons were transferred from anode to cathode The tota volume of gases produced at STP will be approximately 1 67 2 L 3 44 8 L 2 22 4 L 1 O

A ball of mass 10 kg moving with a velocity 10 3 m s along the x axis hits another ball of mass 20 kg which is at rest After the collision first ball comes to rest while the second ball disintegrates into two equal pieces On piece starts moving along y axis with a speed of 10 m s The second piece starts moving at an angle of 30 with respect to the x axis The velocity of the ball moving at 30 with x axis is x m s The configuration of pieces afte collision is shown in the figure below The value of x to the nearest integer is y axis Piece 1 v 10 m s 30 Answer x axis

3 Charge Q is divided into two parts which are then kept some distance apart The force between them will be maximum if the two parts are a Q 2 each b Q 4 and 3Q 4 c Q 3 and 2Q 3 d e and Q e where e electronic charge

where m is the mass of 1 A quantity X is given by electron e is the charge of electron is the permittivity of free space c is the velocity of light and h is the Planck s constant The dimensional formula for X is the same as that of a length c velocity 8ech 3 b frequency d wave number

5 Two identical calorimeters one containing water and the other an unknown liquid are left in a room and allowed to cool Masses of the water the liquid and the calorimeter are equal Specific heat of water is 4 20 J g C and that of the material of the calorimeters is 0 36 J g C If the calorimeter containing water takes 60 s and that containing the unknown liquid takes 40 s in cooling from 50 C to 45 C what is the specific heat in J g C of the unknown liquid a 2 20 c 2 92 Speed distribution of moleculo b 2 68 d 3 40

please Solve and show Why and how poynting vector is v rying with time What realation is obtained How to get t he graph SOURCE NCERT EXEMPLAR 8 19 Poynting vectors S is defined as a vector whose magnitude is equal to the wave intensity and whose direction is along the direction of wave propogation Mathematically it is given by S ExB Show the nature of S vs t graph Ho

A uniform rod of mass M pulled by force F on smooth surface The value of tension T in the rod varies with the distance X from the force end is according to the graph 1 3 TA TA X P X 2 4 TA TA F X

rcuit shown is 6V 400 www 1 2 25 V 2 3 25 V Hint Equivalent resistance of voltmeter is resistors ie 40 Q and 24 2 600 ww V 400 3 4 25 V 60 x 40 60 40 4 6 25 V 24 2 Now PD is in the ratio of series

The conductor in the figure has an excess charge of 3 72 mC If a 2 5 mC point charge is placed in the cavity what is the net charge on the outer surface of the conductor a 6 220 uC b 1 220 mC c All answers are incorrect Od 6 220 mC e 1 220 UC Cavity

A circular road of radius 1000 m has banking angle 45 The maximum safe speed of a car having mass 2000 kg will be if the coefficient of friction between tyre and road is 0 5 Question Type Single Correct Type 1 100 3 m s 2 124 m s 3 99 m s 4 86 m s

diagram and pls explain solution in easy and understanda le way A 2 kg block moving with 10 m s strikes a spring of spring constant N m attached to 2 kg block at rest kept on a smooth floor The time for which rear moving block remain in contact with spring will be 10 m s 2 kg m 2 kg 2 S 31 1s S

5 Calculate simple interest and compound interest assuming that principal amount is 10 000 interest rate is 9 for three years What is the amount different between compound and simple interest 3M

A force gives an object of m an acceleration of 12 m s and an object of mass m an acceleration of 10 m s The ratio of accelerations the force would give to an object of mass m m and m m 1 4 1 3 10 1 2 2 1 4 11 1

An astronomical telescope has magnification having magnitude 5 for distance objects The separation between objective and eye piece is 36 cm and final image is formed a infinity The focal lengths of objective and eye piece are 22 cm 14 cm 30 cm 6 cm 24 cm 12 cm 32 cm 4 cm

A convex surface of radius of curvature 40 cm separates tw 4 medium of refractive indices and 1 50 An object is kept 3 in the first medium at distance of 20 cm from the convex surface What is image position 24 cm from pole 30 cm from pole 18 cm from pole 36 cm from pole

4 A heater of constant power is used to boil water in a pot During heating temperature of water increases from 60 C to 65 C in 1 0 min When the heater is switched off temperature of water falls from 65 C to 60 C in 9 0 min If rate of heat dissipation to the surrounding remains almost constant what proportion of heat received by water during heating would be dissipated to the surroundings a 9 c 12 5 b 10 d 15

Find the ratio of least separation between two points to be distinguished for same objective by a microscope for light of wavelength 5000 and electrons accelerated through 100 V used as illuminating substance 1250 4075 2500 1875

Consider a circuit shown in the figure The switch S is closed at t 0 Find the currents as a function of time through a the inductor and b the battery 192 352 5251 1H 40

Four capacitors each of capacitance C are connected as shown in the figure The ratio of capacitance between P and R to the capacitance between P and Q is C P 01 1 3 4 2 3 C C R

3 In ac circuit when ac ammeter is connected it reads i current If a student uses de ammeter in place of ac ammeter the reading in the de ammeter will be 1 1 2 2 i 3 0 637 i 4 zero

3 A metal cylinder is placed upright on horizontal top of an ice slab of temperature 0 C Initial temperature of the cylinder is 50 C The vertical curved surface and top of the cylinder are adiabatic while its base is perfectly conducting Ice below the base of the cylinder melts and the cylinder sinks into the hole thus formed What fraction of height of the cylinder will ultimately sink Specific heat of material of cylinder is 400 J kg C and density is 9 0 g cm Specific latent heat of melting of ice is 4 0 105 J kg and density is 0 9 g cm Neglect dip in melting point of ice due to increase in pressure a 30 b 50 b 40 c 60 A heater of constant power is used to boil water in o not During ting

3 A particle with total energy E is moving in a potential energy region U x Motion of the particle is restricted to the region when a U x E b U x 0 d U x E c U x E Karnataka NED

The height of a cylindert s decreasing at a constant rate of 4 cm per second The volume remains a constant 17 cubic cm At the instant when the radius of the cylinder is 1 cm what is the rate of change of the radius 0 796 cm s 0 875 cm s 0 670 cm s 0 456 cm s

A liquid of density p flows along a horizontal pipe of uniform cross section A with a velocity v through a right angled bend as shown in Fig What force has to be exerted at the bend to hold the pipe in equilibrium V 45 V