Basic Physics Questions and Answers

If Z is a complex number then mod Z means A None of these B Its angle between real axis and line joining the complex number with origin C Length of vector from origin to that point in a complex plane D It is a always a negative number

A parallel plate capacitor is charged to a potential difference of 50 V It is discharged through a resistance After 1 second the potential difference between plates becomes 40 V Then Question Type Single Correct Type 1 2 3 4 Fraction of stored energy after 1 second is 16 5 Potential difference between the plates after 2 seconds will be 32 V Potential difference between the plates after 2 seconds will be 20 V Fraction of stored energy after 1 second is 4 5

Consider a uniform spherical planet of mass M and radius R Two parallel tunnels are dug perpendicular distance symmetrically from centre A particle is to be thrown from the starting 3R 5 one tunnel such that it enters in another tunnel without making collision with tunnel wall and continue its motion as shown in figure Tunnels are friction less and particle just fits inside the tunnel Conside the planet to be at rest Choose the correct options R 3R 3R 5 5 A Speed with which the particle is to be thrown at starting of one tunnel is B Minimum speed of particle during entire motion is GM 9R 4R C Maximum height achieved by the particle during subsequent motion is 5 GM R

Assertion Intensity of image formed by a spherical mirror of small aperture is more Reason Intensity Aperture 1 Both A and R are true and R is correct explanation of the assertion 2 Both A and R are true but R is not the correct explanation of the assertion 3 A is true but R is false 4 A is false but R is true

Two identical balls A and Beach of mass 0 1 kg are attached to two identical massless springs The spring mass system is constrained to move inside a rigid smooth pipe bent in the form of a circle as shown in the figure The pipe is fixed in a horizontal plane The centres of the balls can move in a circle of radius 0 06 m Each spring has a natural length of 0 06 m and force constant 0 1 N m Initially both the balls are displaced by an angle 6 radian with respect to the diameter PQ of the circle and released from rest The frequency of oscillation of the ball Bis Peeee 16 6 Dees

Question No 110 Single Correct A A A ring of radius 1 5 cm is floating horizontally on the surface of water If this ring has to be raised up then how much vertical force has to be applied to break the film formed between ring and the surface of water Surface tension of water 73 x 10 3 Newton metre B 1 37 x 10 2 N 2 3 10 2 N 5 1 10 N 4 10 2 N Marks 4 00 1 00

Which of the following statement is not correct for following straight line graph y Line 1 Line 2 X A Line 2 has negative y intercept B Line 1 has positive y intercept C Line 2 has positive slope D Line 1 has negative slope

A condenser having capacity 2 0 F is charged to 200 volt and then the plates of the capacitor are connected to a resistance wire Thus heat produced in joule will be Question Type Single Correct Type 1 2 3 2x 10 2 J 4 x 10 J 4 10 0 J

The expression for the equivalent capacitance of the system shown is A is the cross sectional area of one of the plates of side a 1 0A 3d 2 Y Question Type Single Correct Type 3 0A d a FA 6d d 3a a 3d

A solid sphere of radius Rhaving uniform volume charge density p is shown in figure A spherical cavity R of radius is hollowed out from sphere If Vis 2 potential difference between centre of cavity and centre of sphere then

Two identical parallel plate capacitors are connected in series and then joined with a battery of 100 V A sheet of dielectric constant 4 0 is inserted between the plates of second capacitor The potential difference across the capacitors will be respectively Question Type Single Correct Type 1 2 3 50 V 50 V 80 V 20 V 20 V 80 V

There is a 1 mm thick layer of water between a plate of area 100 cm and another very big plate The coefficient of viscosity of water is 0 01 poise Then the force required to move the smaller plate with a velocity of 10 cm sec with respect to the larger plate is B C 10 dyne 100 dyne 1000 dyne 10 000 dyne

if F f x y is a differntial function of two variables x y then dF OF x dx Co OF A partial differentiatial of F C none dy is known as y B total differential of F D mixed differential of F

A solid object of 25 kg and radius 10 cm is suspended by a steel wire of length 5 meter from the roof of a room The height of the roof is 5 21 m When it is made to oscillate it passes by just touching floor If Y 2 x 10 1 N m and the radius of wire is 0 05 cm then what will be the velocity of the object at lowest point B D 10 m sec 2 m sec 2 03 m sec 3 7 m sec Marks 4 00 1 00

1 Average life of radioactive substance X for a and B emissions is 1600 years and 400 years respectively X Y 1 1 4 3 31 2 The ratio of no of two Z B nuclide Y and Z at time t is 2 4 1 4 42 1

5 Match each of the following terms with the correct length of time K U Revolution of the Earth A 27 3 days B 26 000 years Rotation of the Earth

Question No 111 Single Correct A A A big drop of radius R is broken into 125 similar drops If T is the surface tension then what is the change in energy A 4 R T joule 20 xR T joule 16 R T joule 5 R T joule

A ball of mass m be projected horizontally with a speed v 3gR 2 from the top of a smooth hemispherical surface of radius R placed on the ground then the height at which the ball leaves contact with the surface will be 1 3 8R 12 10R 12 m R O 2 4 9R 12 11R 12

A metal sphere having radius ro is charged to potential Vo Sphere is enveloped by thin conducting shell of radius 4ro Shell and sphere are then connected by a conducting wire Then 4ra Electric field near the outer surface of shell is Vo 16ro Field inside the shell is zero Potential of the shell is 4

Question No 31 A particle of mass 1 kg is performing SHM and its displacement any time is given by y 2sin m What will be kinetic energy of particle at t 2 sec O O 288 144 71 288 144

In the circuit shown the battery of V volts has no internal resistance All three condensers are equal in capacity The condenser that carries more charge is C A C B C C C3 A B Oc D Cg D all three carry the same charge

One end of a long thick iron chain of linear mass density is fixed to a sphere of mass m 15 17 m and specific density 1 3 while the other end is free The value of metres The sphere along with the chain is immersed in a deep lake The specific density of iron is 7 Find the height h in metres above the bed of the lake at which the sphere will float in equilibrium Assume that the part of the chain lying on the bottom of the lake exerts negligible force on the upper part of the chain

On a curve xy 9 potential is constant At x 3 magnitude of electric field is 10 N C If strength of field along the curve is constant then find the magnitude of component of field in N C along x axis at x 3 x and y coordinates are in m Y

Hi team I m Harsh Vadher So I got o ption 2 because due to the B of total radius R will be zero at centre and th ere is shell like having R 2 carved an d due to it I got B as option 2 Correct Yes but the sign will be opposite if w e take current from the shell that is cross current E CAPS 18 A Physics 13 A long metallic rod of radius R has a cylindrical hole across the length as shown If the current through the rod is and is uniform through out the complete area then the magnitude of magnetic field at P is 1 Holo 4TR P 2 Holo 3 R

The following data refer to an air conditioning system of a cinema hall for winter conditions Outdoor conditions 10 C DBT 60 RH Required comfort conditions 22 C DBT 60 RH 2000 0 25 m min person The required condition is achieved by heating humidifying and then again by heating The air coming out of the humidifier is having 75 relative humidity Find a the heating capacity of the first heater in kW and the surface temperature of the coil if its by pass factor is 0 3 b the capacity of the humidifier in kg h and c the heating capacity of the second heater and its by pass factor if the Ans 220 kW 40 C 200 kg h 47 3 kW 044 surface temperature of the coil is 25 C Seating capacity Amount of outdoor air supplied

8 points A box 1 ft 1 ft 1 ft of cantaloupes contains 3 7 lbm of dry matter and 91 moisture on a wet basis What is the total mass of the cantaloupes in the box What is the bulk density of the cantaloupes What is the total weight of the cantaloupes What is the moisture content of the melons on a dry basis

Iron rich groundwater contains 0 59mg L of iron carbonate in solution If the coagulating agent used is Ferric Chloride FeCl3 solubility of 900g L how much iron carbonate in mg L will be removed if 1 4mg L FeCl3 is added

For the oscillation of the body in damped oscillation O The amplitude of oscillation of the body decreases with time O The amplitude of oscillation of the body increases with time The amplitude of oscillation of the body remains constant with time None of these

150 g of ice at 0 C is mixed with 100 g of water at temperature 80 C The latent heat of ice is 80 cal g and the specific heat of water is 1 cal g C Assuming no heat loss to the environment the amount of ice which does not melt is 1 100 g 2 0 g 3 150 g 4 50 g

A solid material is supplied with heat at a constant rate The temperature of material is changing with heat input as shown in the figure What does slope DE represent Temperature A B CD O Heat Input 1 latent heat of liquid 2 latent heat of vapour 3 heat capacity of vapour 4 inverse of heat capacity of vapour 2

Two Blocks A B are resting against a wall and the floor as shown in fig Find horizontal force P applied to the lower block that will hold the system in equilibrium Take 0 25 at floor 0 3 at wall and 0 2 between the blocks A 95N B 60 Soold owT P 1000N

Example 32 A bag contains 4 white and 6 black balls A ball is drawn at random and replaced and then again a ball is drawn If this is repeated 4 times what is the probability that 3 black and 1 white ball will be drawn in these 4 trials is repeated 4 times what is the probability that

A solid sphere is rolling on a frictionless surface shown in figure with a transnational velocity v m s If sphere climbs up to height h then value of v should be a 10 7 gh b 2gh c 2gh 10 d 7 gh 0 plockwise without slipping over 1

12 A particle moves a distance x in time t according to equation x t 5 The acceleration of particle is proportional to a velocity 3 2 c distance 2 b distance d velocity 2 3 CBSE Pre 2010

10 g of Ne gas at 500k Pa and 300K is expanded adiabatically to pressur of 250k Pa If the expansion is carried out irreversibly correct among th following is are In x 2 3 log x R 8 3 J K mole Ne 20 g mole In 2 0 69 A AS sur 0 B AG ve D ASS 2 86J K C AS 0 56J K sys

43 Imagine a soap bubble having thickness equal to R 2 where 43 F enga in gorge at even aftfor format e R 2 Rege and f Tagget start R is the outer radious of the bubble If atmospheric pressure is p and surface tension is T Then find out pressure inside the soap bubble 1 Po 2 Po 3 Po 4 Po 4T R 6T R 3T R 9T 2R 4T 1 Po T 2 Po 3 Po 4 Po 6T R 3T R 9T 2R

Q42 A particle of mass m 3kg moves along a straight line 4y 3x 2 with constant velocity 5m s The angular momentum about the origin is O A 12kgm s 1 O B 4 2kgm s 1 O c 6kgm s 1 O D 8kgm s 1

95 A resistance and capacitor network is shown in the figure The charges on the capacitors C and C are Q and Q respectively The values of Q and Q are 50 5V 502 www 5 F 502 www h 502 www 5V a 25 C 0 C c 25 C 25 C C 502 HFwww 5 F 502 C 5V 4 5 02 wwwww 502 wwwwww 502 5V b 0 C 25 C d 0 C 0 C

Q 38 A square steel rod 20 mm x 20 mm in section is to carry an axia load compressive of 100 kN Calculate the shortening in a length of 50 mm E 2 14 108 kN m 0 0854 mm 0 0684 mm 0 0784 mm 0 0584 mm

Coefficient of viscosity eta of turpentine oil flowing through the tube depends upon a Pressure gradient P I where I is the length of the tube b velocity of the oil v c r2 x2 where r is the radius and x is the distance from the axis of the tube Note its r square xsquare

63 When the sun is either rising or setting and appears to be just in the horizon it is in fact below the horizon The explanation for this seeming paradox is that light from the sun bends slightly when entering the earth s atmosphere as shown in figure Assume that the atmosphere has uniform density and hence uniform index of refraction n and extends to a height h above the earth s surface at which point is abruptly stop The angle above the Sun s true position is given by 1 sin 2 sin 3 sin 1 nR R h R R h nR R h nR sin h R R R h CR R h JS Apparent position of the sun From the su Atmosphere

Q32 The following graph shows the velocity of a car against time moving in a straight road EW 10 20 Velocity ms 30 20 10 0 30 40 Time s Which of the following is true 50 60 O The velocity of the car was never above 20 m s O The car stopped moving for 10 seconds after t 40 seconds At t 30 sec the car started moving in the reverse direction O At t 30 sec the car applied brakes for 10 seconds Single c

BRAIN DEVELOPER A Fill in the blanks 1 A computer can understand only two states 2 3 The internal memory is of two types 4 A Flash drive is popularly known as 5 ACD ROM can store up to is rapidly replacing DVD and of data and is ON and Blue ray disc in diameter 700 M

f A B C D I M 0 1 3 4 5 7 9 11 12 13 14 15 is a max term representation of a Boolean function f A B C D where A is the MSB and D is the LSB The equivalent minimized representation of this function is 1 A C D B D 2 ACD BD BC 3 CD ABCD ABCD

Question 3 A specimen of steel 20 mm diameter with a gauge length of 200 mm is tested to destruction It has an extension of 0 25 mm under a load of 80 kN and the load at elastic limit is 100 60 kN The maximum load is 130 mm and diameter at neck is 15 mm Find i The stress at elastic limit ii Young s modulus iii Percentage elongation iv Percentage reduction in area and v Ultimate tensile stress kN The total extension at fracture is

A uniform rod of length L and mass M is held vertical with its bottom end pivoted to the floor The rod falls under gravity freely turning about the pivot If acceleration due to gravity is g what is the instantaneous angular speed of the rod when it makes an angle 60 with the upward vertical Question Type Single Correct Type 1 2 3 1 2 3g 4L 1 2 3 3g 2L 1 2

40 One end of a slack wire Young s modulus Y length L and cross section area A is clamped to rigid wall and the other end to a block mass m which rests on a smooth horizontal plane The block is set in motion with a speed v What is the maximum distance the block will travel after the wire becomes taut a v c V mL AY mL 2AY b v d L 2mL AY mv AY

JASTHAN In a ballistic pendulum an object of mass m is fired with an initial speed v at the bob of a pendulum The bob has a mass M and is suspended by a rod of negligible mass After the collision the object and the bob stick together and swing through an arc eventually gaining a height h Find the height h in terms of m M v and g ballistic cm 5 clar char ca GRICCI THI i 24h i ra ng e 1ch 3 H I fa4d v ell Uch ali ti v 31 1d h n 4 Xin a 1 m M v g Vo

34 The state of an ideal gas was changed isobarically The graph depicts three such isobaric lines Which of the following is true about the pressures of the gas a P P P 3 P3 P2 P b P P P

42 If maximum power that can be develo any one 4 2 resistors is 16 W then the maximum power consumed by the given circuit is 492 wwww www 402 1 48 watt 3 24 watt www 492 ww 2 32 watt 4 16 watt