Basic Physics Questions and Answers

An ideal gas expands from state A to B as shown in the figure P B Choose the incorrect option Work done by the gas is positive Work done by the gas continuously increases Work done by the gas is negative

The time period of oscillation of a simple pendulum is 2TT The length of the pendulum is measured as 1 10 0 01 cm and the time period as T 0 5 0 02 s The percentage error in the value of g is given by T A 5 B 8 D 7 None of these

The density of electron hole pair in a pure germanium is 3 3 1016 m at room temperature On doping with aluminium the hole density increases to 4 5 x 1022 m Now the electron density in m in doped germanium will be A 1 10 0 B 2 10 0 D 0 5 10 0 4 10 0

At room temperature most of hydrogen atoms are in ground state When hydrogen atom receives energy by a process of collision and electron jumps to 2nd excited state The energy gained by electron in jumping up in transition is O 13 6 eV 10 2 eV 12 09 eV

Question No 14 Spherical balls of radius r are falling in a viscous fluid of viscosity n with a velocity v Then what can be said about the retarding viscous force acting on the spherical ball O It is directly proportional to both radius r and velocity v It is inversely proportional to r but directly proportional to velocity v It is directly proportional to r but inversely proportional to v It is inversely proportional to both radius r and velocity v

A load of 2 kg produces an extension of mm in a wire of 3 m in length and 1 mm diameter The Young s modulus of wi will be A 3 25 x 10 0 Nm B 7 48 10 2 Nm C 7 48 x 10 Nm 2 D 7 48 x 10 10 Nm

If the displacement x and the velocity v of particle executing simple harmonic motion are related through expression 4 25x then its time period will be Assuming all quantities in SI units O 2 S O 4 S 02s

Choose the incorrect statement among the following Photodiodes are used to convert light energy into electrical energy Photodiodes are generally used in reverse bias The colour of LED made of GaAso 6 P0 4 is red I V characteristics of solar cell lies in third quadrant of co ordinate axes

In a Potato race 8 potatoes are placed 6 metre apart from each other on a straight line the first being 6m from the basket which is also placed in the same line A contestant starts from the basket and puts one potato at a time into the basket Find the total dis tance he must run to complete the race

Two electrons are moving towards each other each with a velocity of 106 m s What will be closest distance of approach between them 1 1 53 x 10 8 m 2 2 53 x 10 10 m 3 2 53 x 10 6 m 4 Zero 1 New Delhi 110005 Ph 011 47623456

3 The displacement wave graph for two sound I waves P and Q are shown in figure Then the ratio of their intensities is equal to la Assume speed of wave and density of medium is same for both waves y 4 2 0 2 4 1 4 2 4 1 3 1 1 Q S X 4 16

4 Using Gauss s divergence theorem evaluate the following integral where S is the closed surface consisting of the cylinder 2 2 x y a and the circular disks z 0 and 2 2 z b 0 z b and x y a I ff x dy dz x y dzdx x z dx dy S 10

9 Light with wavelength 2 illuminates two slits tha are separated by a distance D each slit has width a The separation of the interference fringes on a screen at distance d away is J5 20 d 1 3 20 21 AD 4

A magnetic needle of magnetic moment 0 2 A m is placed in a region with uniform magnetic field 4 T The maximum torque experienced by the needle will be 1 N m 4 6 N m 0 05 N m 0 8 N m

The velocity of a particle moving with constant 45 acceleration at an instant is 10 ms After 3s its velocity will becomes 16 ms The velocity at 2s before the given instant will be 1 6 ms 2 4 ms 3 2 ms 4 1 ms faf art fred car 10 ms 3s16 m fa 2 1 6 ms 3 2 ms 2 4 ms 4 1 ms

If P XW this equation is dimentionally correct where all the letters represent physic S T quantities then choose the incorrect statement s none is dimensionless U A Units of and are same P W V B Dimensional formulas of P and U C Dimensional formulas of P and D Units of U VW QR S and X are same are same are same

A rod has a total charge q uniformly distributed along its length L If the rod rotates with angular velocity about its end then its magnetic moment is 1 3 9wL 4 90L 3 2 4 qwL 2 qwL 6 V

Figure shows the velocity time graph for a particle travelling along a straight line The magnitude of average velocity in m s of particle during time interval t 0 to t 6 sec is 10a Then the value of a is v m s FATTAN 1 2 3 4 20 20

0 Answer the following by appropriately matching the lists based on the information given in the paragraph List I List II 1 e II III IV 146 6 A 6 A 60 6 60 6 TA 60 B B 6 B 6 6 B A I Q II P III T IV R C I 0 IIS III U IV P A B P 6 Q 6 2 R 6 3 S 0 T 12 U 6 3 B IS IIR III P IVU D I0 11 P III U IV S

questions Out of these 15 questions candidate can As length of a simple pendulum is increased four fold the time period becomes 3 times Read More 4 times Remains unchanged

An uncharged insulated spherical conductor A is brought near a positively charged insulated conductor B then 1 The charge and potential of B both remains constant 2 Both charge and potential of B changes 3 Charge on B remains constant but potential increases 4 Charge on B remains constant but potential decreases

3 For the two vectors A and B The scalar product of the two A may be positive negative or zero B is 0 if A and B are perpendicular to each other C in the direction of the sum of the A and B D is equal to the square of the magnitude of a vector if both the vectors are sa

Position of a particle is given as x t 6t 4 meter which of the following is are correct A Initial position of particle is on right side of y axis B Initially particle is moving in x direction C Distance travelled in first 6 seconds is 18 m D Acceleration is constant throughout the motion

Given A 31 4 and B 61 81 which of following statement is are INCORRECT C 15 A A B 0 Figure shows vectors B B IN 2 D A B 48 BCD F Which of the following is are CORRECT

nonuniform A current passes through a wire of cross section Which of the following quantities are independent of the cross section A the charge crossing in a given time interval B drift speed D free electron density C current density

An ideal battery sends a current of 5A in a resistor when another resistor of value 100s connected in parallel the current through the battery is increased to 6A Find the resistance of the first resistor

L 10 P D volt 10 20 P D Volt Which of the graphs given below represents current voltage characteristics when P and Q are in series v B 10 PD volt 10 20 PD Volt

A conducting sphere of radius a is enclosed by a conducting shell whose radius of inner surface is 2a and that of outer surface is 3a Charge given to conducting shell and conducting sphere are Q and Q respectively then what will be potential at centre of conducting sphere 2a 3a a Question Type Single Correct Type

How will you connect series and parallel 24 cells each of internal resistance 1 ohm so as to get maximum power output across a load of 1002 a number of rows that are connected in parallel b number of cells in series in each row A a 6 03 12 B a 2 DY

In a potentiometer experiment the balancing length of potentiometer of a cell of e m f 1 5V in the secondary is 440 cm A resistance 5 is con nected between the terminals of cell the balanc ing length is 400 cm then a internal resistance of the cell is 0 50 b terminal voltage of the cell is 15 11V c Potential gradient of the potentiometer wire is 1 5 440 V cm d potential difference across the potentiometer wire of length 10m is nearly 3 4V 1 a b are correct 2 a b and c are correct 3 a b and d are correct 4 a b c and d are correct

Question Four identical point charges are placed at vertices of square ABCD of side 10 cm with centre at 0 A point charge placed on Z ax Four identical point charges are placed at vertices of square ABCD of

Two resistance filaments of same length are connected first in series and then in parallel Find the ratio of power dissipated in both cases assuming that equal current flows in the main circuit A 4 1 C 1 2 B 1 4 D 2 1

A wire when mains supply has power dissipation P Now the wire is cut into two equal pieces which are connected in parallel to the same supply Power dissipation in this case is P 2 then P P is 2 A 1 C 3 100cm B 2 D 4 2 cm 2 cm

Two electric bulbs have tungsten filament of same length If one of them gives 60 watts and other give 100 watts then A 100 watt bulb has thicker filament B 60 watt bulb has thicker filament C both filaments are of same thickness D it is impossible to get different wattage

22 Two batteries of different emf and internal resistances connected in series with each other and with an external load resistor The current is 3 0 A When the polarity of one battery is reversed the current becomes 1 0 A The ratio of the emf of the two batteries is 1 2 5 12 2 1 3 3 2 4 1 1

If the kinetic energy of an oblique proj maximum height is half of its initial kinetic energy then the angle of throw with the vertical is 1 30 Cost 3 45 2 37 0 45 4 60 COScus D If resultant of two unit vectors and b is also a

12 Three conductors draw respectively currents of 1A 2A and 4A when connected in turn across an ideal battery If they are connected in series across the same battery then the current drawn will be 1 2 7A 2 3 7A

In the figure shown maximum value of force F for which the two blocks can accelerate horizontally without slipping over each other is g 10 m s 1 2 3 4kg 6kg P 0 3 60 N 80 N 100 N p 0 5 F

The particle displacement of a travelling longitudinal wave is represented by S S x t The midpoints of a compression zone and an adjacent rarefaction zone are represented by the letter C and R Which of the following is true A OS Ox OS OX R B as atlas at 0 C pressure pressure R 2 0S oxx Bulk modulus of air c D Particles of air are stationary mid way between C and R

Figure shows a horizontal rod AB which is free to rotate about two smooth bearing system Two identical uniform rods each of mass m are attached to rod AB symmetrically about the centre of mass O of the rod AB All the dimensions are given in the figure The system is rotating with constant angular velocity in such a way that the upper rod is coming outward from the plane of the paper in the position shown Gravity can be assumed to be absent in the experiment Then choose the correct option s A The hinge reaction at A on the rod AB is downward B The hinge reaction at B on the rod AB is upward A L b C The hinge reaction at B on the rod AB is downward D The angular momentum of the system about point O is NOT along the rod AB

TU Volum 102 Potentiometer d 10 0 volt m measures potential more 2000 accurately because a it measures potential in the open circuit b it uses sensitive galvanometer for null deflection c it uses high resistance potentiometer wire

15 An electric current of 5 A is divided in three branches forming a parallel combination The lengths of the wires in the three branches are in the ratio 2 3 4 Their diameters are in the ratio 3 4 5 If the wires are of the same material then the current in shorter wire is 1 1 4 A 3 0 4 A 2 2 4 A 4 1 6 A

Block B lying on a table weights W The coefficient of static friction between the block and the table is u Assume that the cord between B and the knot is horizontal The maximum weight of the block A for which the system will be stationary is 4 Knot A C W 1 tan 0 D A W tane B B uW tan e D HW sin e

A tennis ball hits the floor with a speed v at an angle 0 with the normal to the floor If the collision is inelastic and the coefficient of restitution is what will be the angle of reflection WBJEE 2020 B sin sine A tan tane C OE 28 8 1 D 0

30 mA 20 mA 5 The magnitudes of the resistances in the four arms of a Wheatstone bridge are 10 12 20 and 24 respectively and the galvanometer resistance is 100 2 If current is sent through the bridge from a cell of emf 1 5 V and of 1 32 internal resistance calculate the current through the 10 resistance 62 5 mA

An elevator carrying a charge of 0 5C is moving down with a velocity of 5 10 ms The elevator is 4m from the bottom and 3m horizontally from Pas shown in fit 2 202 What magnetic field in T does it produce at point P 9 3 m 4 m

0 The deflection in a moving coil galvanometer falls from 50 divisions to 10 divisions when a shunt of 10 2 is connected with it The resistance of galvanometer coil is a 20 Q b 40 Q d 48 c 50 Q

5 Solve the given numerical 5x3 15 1 A cuboid of iron has dimensions of 6 cm x 4 cm x 3 cm If the iron cuboid weighs 560 g me density of iron 2 A force of 2 5 N acts on an object at a normal distance of 40 cm from the turning point Calculate the moment of force 3 Calculate the force which exerts a pressure of 60 pa on an area of 5 m2

3 A body of density p is dropped from rest at a height h into a lake of density p where p p neglecting all dissipative forces calculate the maximum depth to which the body sinks before returning to float on the surface 2020 a c h p p hp R P b d hp P hp p p

In the figure shown the end A of the rod of length L is being pushed down parallel to the inclined surface with a velocity v Let the velocity of end B u and the angular velocity of the rod co Then A u v cosa upward C vsina L B u v downwards D 2v sina L