Basic Physics Questions and Answers

and all respe allg 1 alg 5 3 alg all The diameter of aperture of a plano convex lens is 6 cm and its maximum thickness is 3 mm If the velocity of light in the material of the lens is 2 108 m s its focal length is approximately 1 10 cm 2 15 cm 3 30 cm 4 60 cm Two plano convex lenses of equal focal lengths are arranged as shown 2 alg all 4 Hg 2

There are two wire of same material and same length while the diameter of second wire is two times the diameter of first wire then the ratio of extension produced in the wires by applying same load will be 2020 a 1 1 b 2 1 c 1 2 d 4 1

parallel currents are directed so that one is out of the page and the other is into the page Compare the magnitude of the magnetic field B at any arbitrary uidistant from the wires to the magnitude of the field B at that point from one wire alone

a If the A Magnitude C Magnitude as well as direction D Neither magnitude nor direction Given C A B Also the magnitude of A B and Care 12 5 and 13 units respectively The angle between A and B is R C 2 D T

A rod is free to rotate in horizontal plane about one of its end hinged at point O as shown in figure Point P Q are fixed points located in horizontal plane in such away that PO is perpendicular to rod QO is along length of rod A bullet hits the rod perpendicularly at some distance from point O and gets imbedded into it Then P C O A Linear momentum of rod bullet system will decrease after collision B Linear momentum of rod bullet system may increase Angular momentum of rod bullet system about point P will not change before after collision D Angular momentum of rod bullet system about O may increase after collision

Two beads of mass m are initially at rest at the top of a frictionless hoop of mass M and radius R which stands vertically on the ground The beads are given tiny kicks and they slide down the hoop one of the right and one to the left as shown in figure What is the largest value of m M for which the hoop never rises up off the ground If your answer is a fill 2a in OMR m m M

Kepler s second law regarding constancy of areal velocity of a planet is a consequence of the law of conservation of 2019 a Energy b Angular momentum c Linear momentum d None of these

Two block are connected by a string and A is pulled by a force F 50N If coefficient of friction between the blocks and the ground is 0 2 friction force between the block B and the ground is the string is just slack initially 6 30 A R 30 N B 20kg A 30kg C 40 N F D zero

7 A particle is moving along a vertical circle of radius R The velocity of particle at P will be assume critical condition at C 1 3 7 59R 3gR D R A 37 B 2 2gR 3 4 gR

18 A horizontal disc of mass 1 0 kg mounted on a fixed vertical axle through its centre can rotate without friction On the disc a semicircular groove OP is cut A small ball B of mass 1 5 kg when pushed on the disc towards the centre O the ball enters the groove with a speed 2 0 m s and moves through the groove without friction With what speed will the ball leave the disc Neglect loss of mass due to cutting the groove Va 1 0 m s c 3 0 m s b 1 5 m s d Insufficient information O B P

In the figure the equivalent capacitance between A and B is AO 10 F 10 F HI 16 5 F 1 3 75 F 7 F 3 F 11 6 F HH 6 F 2 5 25 F 1 SE 7 F B

35 A body is moving along a straight line starting from rest with constant power The diagram which correctly represent displacement time s t curve of its motion is S 1 3 S 2 4 S V t

9 A cable that can support a load W is cut into two equal parts The maximum load that can be supported by either part is W a 4 c W b W 2 d 2W

Target IIT 2 A nonconducting disc having uniform positive charge Q is rotating about its axis with uniform angular velocity oo The magnetic field at the centre of the disc is a directed outward 6 having magnitude c directed inwards Ho Qw 4TR Ho Qw 2 R R 0 Q d having magnitude 5 The coordinates of a particle moving in a plane are given by nt and t b sin pt where a b a and pare 25 Wh a b The rest sum of th In nucle nuclei of c The rest m of the rest o norge d In nucle of a ver SECTI This section cor questions is as appropriate bub OBS have to be

Two masses are executing SHM under influence of a vertical spring as shown with an amplitude of 2 cm and angular frequency of 5 rad s When the extension of spring is maximum suddenly the string breaks and 3 kg mass falls off What is the maximum velocity of the 1 kg mass in cm s during subsequent motion 1 320 3 225 m 1 kg m 3 kg 2 175 4 288

A weight of 200 kg is repeatedly dropped freely from a height of 10 m on the head of a pole of mass 50 kg to push it into the ground For every impact the pole penetrates 7 cm into the ground Find the average resistance of the ground Ans 223 440 NI

24 When a pressure of 100 atm is applied on a spherical ball then its volume reduces to 0 01 The bulk modulus of the material of the rubber in dyne cm2 a 10 10 b 100 10 2 c 1 x 10 2 d 20 10

At temperature T a compound AB2 g dissociates according to the reaction 2AB 2 g 2AB g B2 g with a degree of dissociation x which is small compared to unity Deduce the expression for x in terms of the equilibrium constant K and the total pressure P IIT 1994

m th of its volume submerged A metal cube with temperature coefficient of cubical expansion Y has while floating in a liquid with temperature coefficient of cubical expansion y If the temperature of both the liquid as well as the cube increases by 0 the fraction of volume of cube submerged while floating would be 1 Y 0 A 1 Y Y 0 n B n C 2 Y Ym 0 n D 11

At t 0 a transverse wave pulse travelling in the positive x direction with a speed of 2 m s in a wire is described by the function y given that x 0 Transverse veloc 6 X ity of a particle at x 2m and t 2 seconds is a 3 m s b 3 m s c 8 m s d 8 m s

Example 10 12 Distance between the slits in YDSE shown in figure is d 20 where is the wavelength of light used Fir the angle 0 where 1 2 45 d 0 i central maxima where path difference is zero is obtained ii thi

The motion of a particle of mass m is gl x 0 fort 0 s x t A sin 4 t for 0 t 1 4 s A 0 and x 0 for t 1 4 s Which of the following statements is true a The force at t 1 8 s on the particle is 16 T Am b The particle is acted upon by an impulse of magnitude 4 r A m at t 0 s and t 1 4 s c The particle is not acted upon by any force d The particle is not acted upon by a constant force e There is no impulse acting on the particle

c A B a 59 A is directed along north and B is directed south west If C A B then which of the follow relations are correct a C must be equal to A B b C must be greater than A B c C must be greater than A B 0 C al

questions 1 Discuss the different types of motion with examples 2 Differentiate between scalar and vector quantities 3 How is the weight of an object measured Numerical questions 1 A shark swims due East for a distance of 8 9 km turns around and goes due West for 2 8 and finally turns around again and heads 5 7 km due East a What is the total distance travelled by the shark b What is the displacement of the shark Ans a 17 4 km b 11 8 km 2 What is the average speed of a cheetah that sprints 100 m in 4 s What if it sprints 50 m in 2s Ans 25 m s 25 m s

Spring constant of the spring in the figure shown is 100 N m If system released slowly then elongation in the spring is approximately g 10 m s 49 Fc 1 26 cm 3 6 cm 2 kg 4 kg 2 13 cm 4 20 cm O K 100 4x10 2 adax a 4x 41 T 20 CU nga

7 In the circuit shown in figure charge stored in the capacito of capacitance 5 F is HHHHHH 2 F 2 F 2 F 5 F 3 F 4 F a 20 C b zero tr 100 V c 60 C d 30 C

The focal length of spherical mirror if the object distance u 50 1 0 5 cm and image distance V 20 1 0 2 cm will be 1 12 2 0 2 cm 3 10 2 0 1 cm 2 14 3 0 1 cm 4 15 1 0 3 cm

PASSAGE I Two cars A and B travel in a straight line The distance of A from the starting point is given as a function of time by xA t at t with a 2 60 m s and 1 20 m s The distance of B from the starting point is xB t yt St with y 2 80 m s and 8 0 20 m s 1 2 Which car is ahead just after they leave the starting point a Car A moves ahead b Car B moves ahead c Car A and B moves simultaneously d Data is insufficient to decide At what time s are the cars at the same point a 2 27 s b 5 73 s c 2 6 s

Q5 Two plane mirrors are placed parallel to each other at a separation of 6m as shown in figure Find the Xit number of images of the object O separation between 5th image 6 m O www 2 m

a c 1 04 d 0 98 2010 33 The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface having work function 5 01 eV when ultraviolet light of 200 nm falls on it must be 34 a 2 4 V c 2 4 V When b 1 2 V d 1 2 V motic dieti 2010

D For the structure shown in figure moment of about an axis passing through yy is 1 2ML 3 2 45 45 2L 2 ML 3 4ML

Two particles P and Q are projected simultaneously away from each other from a point A as shown in figure The velocity of P relative to Qin ms at the instant when the motion of P is horizontal is 1 10 4 3 3 10 14 Q 20 ms 1 45 A 2 20 4 3 4 20 4 3 PA 20 ms 60

friction between the striker and board is 0 2 The coordinate of the striker when it stops taking point O to be the origin is 1 1 2 2 2 1 2 0 2m s 1 2 X 1 2 0 2 2 2 2 1 1 4 2 2 2 5 10 Particle A moves with speed 10 m s in a frictionless circular fixed horizontal pipe of radius 5 m and strikes with B of double mass that of A Coefficient of restitution is 1 2 and particle A starts its journey at t 0 The time at which second collision occurs is t 0 1 3 A KIN 5N S Fixed B 2 2 4 4 s

If F sin0 2cose of Fis 1 coco A 1 then the minimum positive value 2 4 3 4 2 3 60

C Long answer questions 1 Explain how you would measure the volume of an irregular solid say a stone 2 Explain how you would measure the area of an irregular shape using a square centimetre grid 3 Describe how the density of a solid can be determined Numerical questions 1 Convert 3000 mL into L Ans 3 L 2 The volume of water in a measuring cylinder is 52 mL After dropping a stone into it the water level increases to 63 mL Find the volume of the stone Ans 11 mL or 11 cm 3 Find the area of a a book of length 20 cm and breadth 10 cm and b a table of length 1 5 m and breadth 20 cm Ans a 200 cm b 3000 cm or 0 3 m 4 An object of area 15 cm and height 2 cm has a mass of 50 g What is its density in SI system Ans 1667 kg m 5 A bullet is shot from a rifle with a speed of 720 m s How much time is required for the bullet to strike a target 3240 m away Ans 4 5 s

A cricket ball of mass 150 g is moving with a velocity of 12 m s and is hit by a bat so that the bal gets turned back with a velocity of 20 m s If the duration of contact between the ball and bat is 0 01 s find the impulse and the average force exerted on the ball by the bat lution According to given problem change in momentum of the ball Ap Pf Pi m v u 150 x 10 3 20 12 So by impulse momentum theorem Impulse I Ap 4 8 N s And by time average definition of force in case of impulse Fav I Ap 4 80 480N

Example 2 10 a A 900 pF capacitor is charged Fig 2 31 a How much electrostatic energy is stored by the capacitor b The capacitor is disconnected from the battery and connected to another 900 pF capacitor Fig 2 31 b What is the electrostatic energy stored by the system 9 9 D Qx C 100 V TTTTT a N 0 IN O C LIL 2

Velocity v of a particle depends upon the time t according to the equation v a bt C The dimension of bc will be 1 LT 1 3 L T 2 2 LT 2 4 L T 1 d t

Answer the following questions in brief 1 Why do we need food 2 What is the difference between energy provided by carbohydrates and fats How does it help to include sufficient roughage in the diet What makes a balanced diet 3 4 5 How is freezing different than the drying in preserving food

a Like there are landforms on land ocean floor also has submerged landforms because i There is land under water ii There are volcanoes under water iii Land is continuous and there is water in deeper parts Though land is continuous its level is not the same everywhere like

9 In a comman base connection a certain transistor has an emitter current of 10mA and collector current of 9 8 mA Calculate the value of the base current

B Explain the following terms 1 Translatory motion 4 Displacement 2 Oscillatory motion 5 Average speed C Distinguish between the following 1 Translatory motion and rotatory motion 2 Distance and displacement 3 Uniform and non uniform motion 4 Mass and weight D Short answer questions 1 List any two types of motion 2 What is a scalar quantity Give an example 3 What is a vector quantity Give an example 4 Define weight What is its SI unit 3 Random motion 6 Weight

The area bounded by the curves y loge x and y log x is a e 2 sq units e sq units c b 3 e sq units d e 1 sq units

Q9 Charges of 2 0 x 106 C and 1 0 x 106 C are placed at the corners A and B of a square of side 5 0 cm as shown in Fig How much work will be done in moving a charge of 1 0 x 10 C from C to D against the electric field D 91 5 cm C 5 cm 92

15 Why is the emitter the base and the collector of a BJT doped differently 16 Which method of biasing is used for operating transistor as an amplifier

A man generates a symmetrical pulse in a string by moving his hand up and down At t 0 the point in his hand moves downward The pulse travels with speed of 3 m s on the string his hands passes 6 times in each second from the mean position Then the point on the string at a distance 3m will reach its upper extreme first time at time t 1 1 25 sec Jution Frequency of wave Total time taken 2 3 3 3 3T 4 2 1 sec 3 T 1 s 3 VT 3 1 25 sec 3 13 12 sec 1m 4 none Ans 1

Example 9 5The earth takes 24 h to rotate once about its axis Ho much time does the sun take to shift by 1 when viewed fro the earth Solution Time taken for 360 shift 24 h Time taken for 1 shift 24 360 h 4 min

1 AB is an inclined plane of inclination 30 with horizontal Point O is 20 m above point A A particle is projected horizontally from O leftwards and it collides with the plane AB perpendicularly Speed of the particle at the time of projection should be g 10 m s O a 13 m s c 4 5 m s B 30 A 20 m b 8 3 m s d 2 3 m s

Paragraph for question nos 14 Katrina and Kareena were crossing a river which is flowing towards right at constant speed 5 m min travelling in two different boats having same speed in still water They have taken photographs of the river banks at t 0 t T t 2T times Bo Co are two trees on other bank of river Distance shown in diagram are in m T 1 min Photograph taken by Katrina Bo t 0C B t TC Box t 2T Co 10 3 5 303 Bo 15 3 15 3 Photograph taken by Kareena t 0 0 Co Bo 10 3 t t Con B O 5 31 t 2T Co O 14 Mark correct option b Katrina s boat has crossed the river in minimum time and Kareena s boat has crossed the river along the shortest path b Kareena s boat has crossed the river in minimum time and Katrina s boat has crossed the river along the shortest path c Kareena s Boat as well as Katrina s boat has crossed in the minimum time d None of these 15 What is the distance between B and C a 10 m b 30 3 c 30 m d None of these 16 Mark the correct option a Velocity of boat in still water will be 10 m min b Velocity of boat in still water will be 10 3 m min

17 A train is moving with a velocity of 30 km h 1 due East and a car is moving with a velocity of 40 km h due North What is the velocity of car as appears to a passenger in the train