Physics Questions

5 Infinite number of masses each of mass 3 kg are placed along the y axis at y 1 m 3 m 9 m 27 m The magnitude of resultant gravitational potential in terms of gravitational constant G at the origin y 0 is 1 4 5 G unit 3 3 G unit 2 G unit 4 9 G unit

dentical parallel plate capacitors of capacitance Ceach have plates of area A separated by a distance d The space between the plates of the two capacitors is filled with three dielectrics of equal thickness and dielectric constants K K and K The first capacitor is filled as shown in fig 1 and the second one is filled as shown in fig II Assume the plates of the capacitor are at the top and bottom in the two figures If these two modified capacitors are charged by the same potential V the ratio of the energy stored in the two would be E refers to capacitor 1 and E to capacitor II A B 1 11 E K K K K K K K K K K K K E E K K K K K KK K K E 9K K K YOU MARKED X

The force exerted by the floor of an elevator on the foot of a person standing there is more than the weight of person if the elevator is A going up and slowing down C going down and slowing down B going up and speeding up D going down and speeding up

The dimensions of the quantities in one or more of the following pairs are the same Identify the pair s a Torque and work b Angular momentum and work c Energy and Young s modulus d Light year and wavelength

Let A i j and B 1 1 The magnitude of a coplanar vector C such that AC B C AB is given by Online April 16 2018 a c 20 9 b d 10 9 9 12

40 A block of metal is heated to a temperature much higher than the room temperature and allowed to cool in a room free from air currents Which of the following curves correctly represents the cooling 7 Temperature of block 3 time 2 time time Rash Educational Services Pvt Ltd Regd Office Aakash Tower 8 Pusa Road New Delhi 110005 Ph 011 47623456

The pressure P of an ideal gas varies with its absolute temperature T as shown in figure The molar heat capacity of gas during this process is R is gas constant P A 1 7 R C 2 5 R T B 3 25 R D 4 2 R

ALLEN 35 Shown in the figure is a bi convex lens made 35 of different transparent strips of two different refractive indexes If the parallel rays of light is incident on the lens then select INCORRECT statement n n 1 rays will intersect before focussing 2 rays will be focussed at two different points 3 the lens may have four focal points different from each other 4 None of the these f t 2

Statement A For a virtual object convex lens forms real erect and diminished image Statement B For a virtual object concave lens always forms virtual image Assume lens material is denser than surrounding medium in both cases 1 Both statement A and B are true 2 Statement A is true Statement B is false 3 Statement A is false Statement B is true 4 Both statement A and B are false

Example 6 To what potential we must charge an insulated sphere of radius 14 cm so that the surface charge density is equal to 1 Cm2 Solution Here r 14 cm 14 10 m o 1 Cm 106 Cm 2 1 4tr o 4nso 22 9 10 x4 14 10 V 1 9 4nsor T 1 4160 4 ro 2 10 V X

size of earth starts from rest from h R above the earth s surface It reaches earth in time 2h 9 a t c t h 9 2h 3g b t d t 4h 2601 3g d to raise a satellite to

TON S LAWS A body of mass 2 kg moving on a horizontal surface with an initial velocity of 4 m s comes to rest after 2 sec If one wants to keep this body moving on the same surface with a velocity of 4 m s the force required is A 8 N B zero C 2 4 N D 1 2 N

A man weights 80 kg He stands on a weighing scale in the lift which is moving upwards with a uniform acceleration of 5 m s What would be the reading on the scale g 10 m s A zero B 400 N C 800 N D 1200 N

Spherical shell A is made up of insulating material and carries electric charge uniformly distributed over its surface while Spherical shell B is made up of conducting material and carries no charge C and C are centres of Shell A and Shell B respectively Choose the correct statement 1 2 3 4 Shell A Question Type Single Correct Type Shell B electric field at centre C of shell B due to charge of shell A is zero electric field at centre C of shell B due to induced charges on surface of shell B is zero direction of electric field at point A on shell B due to induced charges on surface of shell B is radial direction of electric field at point P on shell B due to induced charges on surface of shell B is radial

The truth table for the circuit s shown in figure is A B A 0 0 1 1 A 0 0 1 1 BY 01 1 0 0 0 1 0 BY 0 1 1 1 01 1 0 ABY

5 Find out the velocity of Block D m s E 8 m s 2 m s A BI C D m s A VD 22 m s upward direction B VD 22 m s downward direction A VD 23 m s upward direction

Choose the correct option for a semiconductor It has negative temperature coefficient of conductance For pure semiconductor at room temperature ne nh It works as insulator at 0 C All of these

Let the index of refraction for air be 1 00 and the index of refraction for the type of glass in this problem be 1 56 A light beam in air has an angle of incidence of 62 at the surface of a glass plate a Calculate the angle of reflection in degrees b Calculate the angle of refraction in degrees

You have two vectors A and B They add up If the size of each vector is maintained the maximum possible size of the resulting vector is achieved if Select one to Vectors point in the same direction b Vectors point in opposite directions c Vectors point in different directions but not opposite

hermal Properties of Matter Board Competitive Exams Coefficient of volume expansion of mercury is 0 18 x 10 PC If the density of mercury at 0 C is 13 6 g cc then its density at 200 C is 1 13 11 g cc m 16 11 pics 2 52 11 g cc 4 26 11 gior

e M In figure a lamp P is in series wi inductor L When the switch S is closed the brightness of the lamp rises relatively slowly to its full brightness than it would do without the inductor This is due to m mmmm So HH B 1 the low resistance of P 2 the induced emf in L 3 the low resistance of L high voltage of the battery B

Three blocks of masses 2 kg 3 kg and 5 kg are connected to each other with light strings and are then placed on a smooth frictionless surface 9 The value of Fis 2 kg A 2 N B 3 N 2 1 ms T 3 kg The system is pulled with a force F from the side of the lighter mass so that it moves with an acceleration of 1 ms 2 T and T denote the tensions in the other strings T2 5 kg C 5 N D 10 N

15 What is the equivalent resistance of the arrangement of resistors shown here 10 Q www www 5 0 2 6 0 2 3 0 2 wwww 2 0 92 wwww 4 0 2 4 0 wwww 5 0 Q 8 0

A charge q is kept just outside a cube o extension of digonal GA The magnitude c electric flux of face ABCD is q 1 8E0 E B F D H q 2 6 C G

Two blocks each of mass M are resting on a frictionless inclined plane as shown in figure Then A the block A moves down the plane C both the blocks remain at rest 60 30 B the block B moves down the plane D both the blocks move down the plane

A particle of mass 1 kg has been thrown with init speed 20 m s making an angle 60 with th horizontal ground The angular momentum of t particle about point of projection when the projec is at the highest point is g 10 m s 1 150 kg m s 2 300 kg m s 3 Zero 4 100 kg m s

3 25 A solid sphere of radius R is gently placed on a rough horizontal ground with an initial angular speed wo and no linear speed the angular velocity and linear velocity v at the end of slipping is 1 wo w R 3 2 5 2 5 Wo 5 Roo 2 4 N 3 NIN N 3 N N 0 3 o Rwo Rwo

50 Four particles each of mass M move along a circle of radius R under the action of their mutual gravitational attraction The speed of each particle is a L c GM R GM 2 2 1 VR b 2 2 GM R GM 2 2 1 d VR are 1 CI

A glass sheet 1 40 m thick is suspended in air In reflected light there are gaps in the visible spectrum at 529 nm and 605 00 nm Calculate the minimum value of the index of refraction n of the glass sheet that produces this effect

6 A parallel plate air capacitor consists of two plates each of area 0 01m separated by a distance of 0 1 mm Vit is charged to a potential of 50 volt Calculate a capacitance b charge and c energy stored Ans a 885 4pF b 0 0443 C c 1 11 x 10 J 7 Three capacitors of capacitances 2 F 3uF and 6 F are first connected in series and then in parallel 1 111

3 273 C 4 273 K A hole is drilled in a copper sheet The diameter of hole is 4 24 cm at 27 0 C Diameter of the hole when it is heated to 35 C is 1 Less than 4 24 cm 2 Equal to 4 24 cm 3 More than 4 24 cm 4 Data insufficient 12

X X X X X X X X X X X RX X X X X X X X X X X X X X X X X X Vo If this rod length 1 is released wit velocity V then 0 1 It will continue to move with constant 2 It will accelerate 3 It will stop after sufficiently long tim 4 None of these dana in ostabli

B A light frictionless pulley is suspended with the help of a light spring One end P of a light inextensible thread that passes over the pulley is free and the other end is tied to another light spring that is affixed to the ground at its lower end as shown in the figure Stiffness of both the springs is k 500 N m The free end P is h 10 0 cm above the ground What minimum pull at the end P will bring it to the ground KUPKFORNO

A mass of 1 kg attached to the bottom of spring has a certain frequency of vibration The following mass kg has to be added to it in order to reduce the frequency by half Answer DESELECT

If a copper plate is allowed to oscillate between 3 N pole S pole of a magnet like a simple pendulum then 1 it will oscillates for o time 2 it s motion is accelerated 3 it will not oscillate 4 it s oscillation is damped

A p type semiconductor Is electrically positive Is electrically negative Is electrically neutral Is electrically positive for excessive doping

A convex lens is made of two different materials having radius of curvature of surface A and surface B as 25 cm and 24 cm respectively The effective focal length of lens is A B H 1 5 O 75 cm 4 75 cm 50 cm O 30 cm Reload H 1 8

You have two coaxial cylindrical conducting shells one with radius a and the second radius b a b The inner shell radius a is at potential V 0 the outer shell radius b is held at potential Vo Find the potential V r everywhere assuming the cylinders are infinitely long b V 0 O

An airplane must achieve a speed of 200 0 km h before it gets to the end of the runway If the runway is 1800 m long what minimum acceleration must the plane have 0 95 m s O 0 78 m s2 1 0 m s 0 86 m s

17 A value of co for which the current amplitude is 17 1 2 power dissipated by the circuit becomes 1 double 3 one third times its maximum value At this value the 2 one fourth 4 half initially charged is connected 18 T 1 3 Uch faels cha YZ

9 An electron beam has the diameter 1 mm the electrons have the kinetic energy T 10keV What is the charge density in the beam if the total current is 2 10 A 10 The mobility of electrons u in a conductor is defined by the equation vdrift E Find an expression

A solid cylinder of radius 4 cm and length 50 cm emissivity 0 85 and temperature 127 C is radiating energy at rate P in surrounding at temperature 27 C If cylinder is stretched and new radius is 2 cm then energy transfer rate is P2 Then find P1 P2 A B C D 54 101 54 100 52 101 52 100 Correct Answer

4 none of these 2 An applied voltage signal consists of a superposition of a d c voltage and an a c voltage of high frequency The circuit consists of an inductor and a capacitor in series then 1 d c signal will appear across L and C 2 d c signal will appear across C and a c signal across L 3 d c signal will appear across L and a c signal across C across L and C a c signal will appears 3 racht 4 3 faya fa 1 2 3 4 LACT C uchra L LA

When a capacitor initially charged is cor to a inductor the change on the capacit the current in the circuit exhibit the phenom 1 electrical oscillations 2 induction 3 power factor 4 All of these

24 A uniform solid cylinder of radius R is spun and then placed on an incline having coefficient of friction tane 0 is the angle of incline The cylinder continues to spin wihout falling for time 1 2 3 4 Ro 3gsin0 Ro 2gsin0 Ro gsine 2Rw gsing 0 Wo

Two particles P and Q start their motion from same point along same straight line Pmoves with constant velocity 50 m s and starts moving with constant acceleration 10 m s Separation between them after 1 s will be m

If sun radiates electromagnetic energy of 18 3 9 x 1026 watt and radius of sun is 6 96 x 108 m then intensity of sunlight at the solar surface will be 1 5 6 x 106 W m 3 4 2 x 106 W m 2 6 4 x 107 W m 4 4 2 x 10 W m

A man wants to reach point B on the opposite bank of a river flowing at a speed u as shown in the figure What minimum speed relative to water should the man have so that he can reach directly to the point B B A B C 2 30 with upstream u 45 u u 45 with downstream 45 with upstream Correct Answer

1 A truck with a mass of 40 000 kg rolls down a hill without friction from an initial height of 200 m It rolls over a 300 m long flat section with a coefficient of friction 01 and then rolls up a hill of 30 degrees with a coefficient of friction of 0 2 How far up the hill will the truck roll before coming to a stop 200 0 m P 0 0 1 300 m d 30 0 2

A particle is placed inside a hemispherical bowl which rotates about its vertical axis with constant angular velocity w It is just prevented from sliding down when OP is inclined at 45 with the axis O is the centre of the sphere and P is the position of the particle The radius of the bowl is 10 2 m and coefficient of friction between the particle and the bowl is 0 5 Find the magnitude of angular velocity w assuming g 10 m s A 1 3 R P Correct Answer