Basic Physics Questions and Answers

8 In the circuit shown in figure R R R3 392 and e m f of each cell is E 4V and negligible internal resistance All ammeters are ideal Choose the correct option A Reading of ammeter A in ampere is 4 3 B Reading of ammeter A in ampere is 8 3 C Reading of ammeter A3 in ampere is 2 D Rotential difference between nint b E R E R a HA R3

Solvelancer Test During an observatory experiment the scientist found that the speed with which earth revolves around the sun is 3 10 7 rad sec in a circular orbit of radius 2 107 km The value of force exerted by the sun on the earth in newton N Solvelancer Test a b c d D a O b 36 x 1020 18 x 1020 72 x 10 20 36 x 10 2

The current density of a solid cylindrical wire of radius R as a function of radial distancer is given by J r Jo 1 R The total current in the radial region r 0 to r will be 4 a c 5J R 32 3J R 64 b d 5J R 96 JORR 128

8 What minimum horizontal speed should be given to bob of a simple pendulum of length 1 so that it descri Ca complete circle Solution Suppose the bob is given a horizontal speec at the bottom and it describes a complete vertical cir Let its speed at the highest point be v Taking gravitational potential energy to be zero at the bott the conservation of energy gives 113 1 2 mvo 2 mu 2mgl

Two wooden blocks are moving on a smooth horizontal surface such that the mass m remains stationary with respect to block of mass M as shown in the figure The magnitude of force F is 77 F 1 M m g tane 3 ma cose Smooth M m 0 08 777 2 mg tane 4 M m a cosece

27 sh A light ray is incident upon a prism in minimum deviation position and suffers a deviation of 34 If the shaded half of the prism is knocked off the ray will 1 suffer a deviation of 34 2 suffer a deviation of 68 3 suffer a deviation of 17 4 not come out of the prism EET

The work done on a particle of mass m by a force 1 23 2 k being a constant of appropriate dimension when the particle is taken from the point a 0 to 0 a along a circular path of radius about the origin in the xy plane is 2km a kn A x 2 9 92

of the following is a null vector A Velocity vector of a body moving in a circle with a uniform speed B Velocity vector of a body moving in a line with a uniform speed C Position vector of the origin of the rectangular co ordinate system D displacement vector of a stationary object FITIFF Hyderabad Classes Limited 5 9 14 B Saifabad Opp Secretariat Hyderabad 500 063 Phone 040 66777000 03 Fax 048

ent on the interface of glass and air as shown in the figure If green light is just totally internally reflected then the emerging ray in air contains sinde d UA 1 Yellow orange red 2 Violet indigo blue 3 All colours 4 All Air Glass White Green A B 39 40

22 Three ants A B and C are crawling on a large horizontal tabletop always occupying vertices of an equilateral triangle size of which may vary with time If at an instant speeds of A and B are uA and UB which of the following conclusions can you make for speed uc of C b v 0 5 v U d v v UB a vc 0 5 v UB c UC UA UB

A dipole of dipole moment P 21 31 4k is placed at point A 2 3 1 The electric potential due to dipole at point B 4 1 0 is equal to All the parameters specified here are in SI units 1 2 109 volts 2 2 109 volts 3 3 109 volts 4 3 109 volts

3 A body changes its position according to the relation x 2 6t What is the shape of position time graph of the body What will be the intercept on the x axis assuming x to be in metre and t in second Ans Straight line 2 metre

A car A moves due north at a speed of 40 km hr while another car B moves due east at a speed of 30 km hr Find the velocity of car B relative to car A both in magnitude and direction 1 40 km hr at an angle tan 3 5 55 5 east of south 2 50 km hr at an angle tan east of south 4 3 40 km hr at an angle tan 2 east of south 4 50 km hr at an angle tan east of south 1

On a rough inclined plane a long plank A is placed A uniform disc B having mass same as plank is rolling without slipping on the plank The minimum value of coefficient of friction between the plank and the inclined plane such that the plank can remain stationary is A 2 tan 0 3 B 3 tan 0 2 C 4tan 3 D none B 50

50 A body is at equilibrium and is being acted upon by three forces F F F F 31 4 2k F i j k Calculate the inclination of the third force with the negative x axis 1 0 cos 3 cos 1 1 3 4 2 0 cos 4 0 cos 4 42 4

The component of a force of 100 N acting at an angle of 30 with the X axis is A 70 72 N 70 72 N B 50 N 50 N C 50 N 50 3 N D 50 3 N 50 N If the X component of a vector in X Y plane is 3 times its Y component angle made by it with X direction is A 30 B 45 C 60 D 90

Three masses are connected as shown in figure on a horizontal frictionless surface and pulled by a force of 60 N The tensions T and T are in the ratio A B 3 kg 1 1 12 kg 1 5 Correct Answer 1 4 2 15 kg 60 N 30

In the sum A B C vector has a magnitude of 13 7 m and is angled 46 6 counterclockwise from the x direction and vector has a magnitude of 15 4 m and is angled 22 0 counterclockwise from the x direction What are a the magnitude and b the angle relative to x of B State your angle as a positive number a Number Mi Units m

ABCD is a square frame of conductor of electrical resistivity p The frame lies in a vertical plane PQ is an imaginary boundary separating space into two parts Left of PQ a uniform gravitational field g exists figure whereas no gravitational field is present right of PQ The k mgh electrical potential difference between A and B will be 4 m is mass of electron Find k e is charge on an electron and

Mark the incorrect statement among the following A given conducting sphere cannot be charged to a potential greater than a certain value A given conducting sphere can be charged to a potential less than certain maximum value A given conducting sphere can be charged to any extent O The metallic sphere may be negatively charged

Select the incorrect option for the Ellingham diagram AG versus T O AG is calculated for reduction of 1 mole of metal oxide O AG is calculated for the oxidation of metal with 1 mole of 02 O Straight line parallel to temperature axis variation shows negligible change in entropy O Metal oxide with most ve value of AfG is stable to heat

i A large number of atoms or molecules of a substance aggregate together to form species having size in the colloidal range these species are called a multimolecular colloids b macromolecular colloids c solid sol d omulsion

2 17 The activity of a certain radionuclide decreases to 15 percent of its original value in 10 days What is its half life In 0 15 1 9 2 3 50 days 4 3 8 days 1 3 00 days 3 3 65 days

A ball weighing 10 g hits a hard surface vertically with a speed of 5 m s and rebounds with the same speed The ball remains in contact with the surface for 0 01 sec The average force exerted by the surface on the ball is 1 100 N 3 1 N 2 10 N 4 0 1 N

15 Monochromatic green light of wavelength 5 x 107 m illuminates a pair of slits 1 mm apart The separation of bright lines in the interference pattern formed on a screen 2 m away is 1 0 25 mm 3 1 0 mm 2 0 1 mm 4 0 01 mm

Q 5 The masses of 10 kg and 20 kg respectively are connected by massless spring as shown in the figure A force of 200 N acts on the 20 kg mass At the instant shown the 10 kg mass has acceleration of 12 m s What is the acceleration of 20 kg mass g 10 m s 20 kg 10 kg ooooooo 2 1 12 m s 2 3 10 m s 200 N 2 4 m s 4 zero

If light is incident on the interface of tw ransparent media then 1 Frequency of light in optically dense medium is greater 2 Velocity of light in optically denser medium is greater 3 Intensity of light is greater in optically rare medium 4 Phase of light wave doesn t change due to refraction

1 2 2 The formula S ut at where S is the 3 distance travelled u is the initial velocity a is the acceleration and t is the time is 1 only dimensionally correct 2 dimensionally incorrect 3 dimensionally and numerically correct 11

Two positive charges of 12 C and 8 C are placed 10 cm apart in air The work done to bring them 4 cm closer is O 3 5 J 5 8 J O 6 4 J 9 3 J

45 In the given figure the switch S is closed time t 0 Q Qg and Qc are charges on th capacitor A capacitor B and capacitor C in th steady state respectively Choose the corre statement 100 1002 AIH 1 F 60V 1 QA QB Qc 2 Q Qc QB 3 Qc Q QB 4 Qc QB QA 1002 ww 3 F 2 F 1002

A particle Stal time curve is shown in figure Determine the positi of particle after 6 seconds assuming partic moves in a straight line path along x axis v in m s 10m s 1 54 m M 3s 6s t in sec 2 50 m

10 A thin square steel plate with each side equal to 10 cm is heated by a blacksmith The rate of radiated energy by the heated plate is 1134 watts The temperature of the hot steel plate is Stefan s constant o 5 67 x 10 watt m K emissivity of the plate 1 1 570 K 3 2500 K 2 1189 K 4 750 K

A point mass in m 20 kg is suspended by a mass less spring of constant 2000 N m The point mass is released when elongation in the spring is 15 cm The equation of displacement of particle as a function of time is Take g 10 m s A B y 10 sin 10 t y 10 cos 10 t y 10 sin 10t 6 00000 3 m My Answer Correct Answer

6 Three particles two with masses m and one with mass M might be arranged in any of the four configurations shown below Rank the configurations according to the magnitude of the gravitational force on M least to greatest

In electromagnetic waves travelling in vacuum 1 The electric field E is always perpendicular to the magnetic field B 2 The cross product Ex B always gives the direction in which the waves travel The fields E and B vary sinusoidally 3 4 T There is a phase difference of 2 E and B between

Solution Answer 2 mg Since acm 0 mg T 0 J mg Torque about C O M TR mgR mR mgR la a 2 10 2g R 2g A aR acm aR 0 xR 2g R This is the acceleration of the rope he rope is not slipping since A cylinder is wrapped around its lateral surface by a rope as shown in the figure The rope is moved upwards such that cylinder does not fal from its initial position Initially it was at rest What is the acceleration of the rope mg 2g 3g 2

5 For a man walking towards east with a velocity of 5 km hr rain appears to fall vertically down When the man begins to walk towards west with a velocity of 3 km hr the rain appears to fall at an angle of 60 to the vertical The magnitude of velocity of the rain when the man stops walking is 139 Km hr Then N is equal to N

3 25 cm 4 25 4 cm 25 2 cm 14 4 Four lenses having the focal length of 15 cm 20 cm 150 cm and 250 cm respectively are provided to make an astronomical telescope The focal length of the eyepiece to produce the largest mangification should be 1 250 cm 2 150 cm 3 20 cm 4 15 cm 3 25 cm 50 cm 4 25 4 cm 25 2 cm Rfade cm 250 cm a efter att 1 250 cm 2 150 cm e as 3 20 cm 4 15 cm 15 cm 20 cm 15 cita ei and fra fag fan de

Q 7 The specific heat of a substance is given by C a bT where a 1 12 kJ kg K and b 0 016 kJ kg K2 The amount of heat required to raise the temperature of 1 2 kg of the material from 280 K to 312 Kis 1 205 kJ 3 225 kJ 2 215 kJ 4 235 kJ FO

In the shown circuit if P P2 and P3 are power dissipated in the resistor 100 20 and 40 respectively then 1092 21V 292 www 202 P 10 W P 2W P3 1 W P 4 W 1092 60 452 2V 80 1622 T5V

Question No 1 A infinite line charge produces a field of 9 x 104 N C at a perpendicular distance of 2 cm The linear charge density is O 107 Cm1 2 10 Cm 10 Cm1 4 x 10 7 Cm1

For the L shaped conductor in a uniform magnetic field B shown in figure the emf across its ends when it rotates with angular velocity w about an axis through one its ends O and normal to its plane will be X L X X

4 hydrogen atom in ground state and this is absorbed by the electron This electron enters a magnetic field of induction B perpendicular to its direction The radius of the circular path on which the electron will move is 1 2 3 1 2Rhcm eBV 5 1 Rhcm eBV 2 is incident on a 1 2Rhcm eB V 3

A parallel plate capacitor of plate area 0 2 m and spacing 10 2 m is charged to 10 volt and then disconnected from the battery and pull apart to double the plate spacing 1 Final charge on the capacitor becomes two times of initial 2 Final charge becomes half of initial value 3 Final voltage on the capacitor will remain 10 Volts 4 Final voltage on the capacitor is 2 10

In Young s double slit experiment 10 4 d distance between slits D distance of screen from the slits At a point P on the screen the resulting intensity is equal to the intensity due to individual slit Io Then the distance of point P from the central maximum is 6000 2 mm 3 0 5 mm 2 1 mm 4 4 mm

Q 28 A particle of mass 5 x 105 kg is placed at the lowest point of a smooth parabola having the equation 20 x y x y in m esbie Here y is the vertical height If it is displaced slightly and it is constrained to move balong the parabola the angular frequency in rad s of small oscillations is Q

Two vectors A and B lie in plane and another vector C lies outside this plane then the resultant of these vectors a can be zero c lies in the plane containing A B d lies in the plane containing A B b can never be zero

A river is flowing from west to east at a speed of 5 m min A man on the south bank of the river capable of swimming at 10 m min in still water wants to swim across the river in shortest time He should swim a due north c 30 west of north b 30 east of north d 60 east of north

2 23 Length of steel rod so that it is 5 cm longer than the copper rod at all temperatures should be cm a for copper 1 7 x 10 1 1 x 105 C slom 1 0 105 C and a for steel doss to earn ai

Poil is 30 A coil of effective area 4 m is placed at right angles to the magnetic induction B The e m f of 0 32 V is induced in the coil When the field is reduced to 20 of its initial value in 0 5 sec Find B in wb m