Basic Physics Questions and Answers

A lift starts from rest with constant upward acceleration It moves first 4 metre in 5 second A man in lift holds a packe of mass 2 kg by a string The tension in string during the motion is g 9 8 m s 16 5 N 20 2 N 15 7 N hr min 26 4 N

Copper contains 8 4 1028 free electrons m A copper wire of cross sectional area 7 4 10 7 m carries a current of 1 A The electron drift speed is approximately A 3 x 108 m s B 10 m s C 1 m s D 10 4 m s E 10 23 m s ep

13 12 Calculate the resistivity of an n type semiconductor from the following data density of conduction electrons 8x 10 cm density of holes 5 x 10 2 cm mobility of conduction electron 23 x 10 cm V s and mobility of holes 100 cm V 1 1 V s S

3 8P 4 16P 16 A steel scale calibrated at 25 C has been employed to measure the length of copper pipe at 25 C However the readin has been taken at 45 C If therma coefficient of linear expansion of steel an copper are 3 x 10 5 per C 1 and 2 10 per C respectively then percentage erro in reading taken is 1 0 01 3 0 01 2 0 02 0 05

39 Figure shows two small blocks placed on smooth horizontal surface They start moving from the same line with forces 2F and F respectively acting on the blocks Their momenta and kinetic energies at the instants of crossing the finishing line as shown in figure are PA PB and KA KB Then choose the correct option A m m 2F B 2m F a KA KB PA PB Finish line b KA KB PA PB

On a disc of radius R a concentric circle of radius R 2 is drawn The disc is free to rotate about a fritionless fixed axis through its centre and perpendicular to plane of the disc All three force in plane of the disc shown in figure are exerted tangent to their respectively circular periphery The magnitude of the net torque about centre of disc acting on the disc is F 37 2F R 2 R F

A coin kept at a distance r cm from the axis of rotation of a turn table just begins to slip wher the turntable rotates at an angular speed of o rad s If this distance is tripled then at wha angular speed of the turntable will the coin begin to slip A 300 rad s B 300 rad s C rad D 001 3 rad s

A train takes round turn on a banked bend of radius 300 m at speed of 20 m s The mass of train is 106 kg The spacin between rails is 1 5 m Through what height outer rail be raised w r t inner for safe turning of train 10 cm 20 cm 30 cm 5 cm

gas is n the taken The to B A thermodynamic cycle on an ideal gas is shown in the V T graph Which of the following P T graphs represents the same cycle V4 1 3 E P4 P4 T T B 2 CT 4 P4 T T

Solids expand on heating because X Kinetic energy of the atoms increases B C Potential energy of the atoms increases Total energy of the atoms increases The potential energy curve is asymmetric about the equilibrium distance between neighbouring atoms

child is swinging on a swing in sitting position If he stands up on the swing then periodic me of the swing will A remains the same 3 increase if the child is tall and decrease if the child is short C increase decrease

If the dielectric strength of air is 4kV mm what is the greatest capacity which can be obtained in a volume of 12cm x 10cm 8 cm using air as a dielectric and using a working potential of 200 V 1 0 62 F 3 3 4 F 2 1 2 F 4 5 6 F

The wavelength of the waves arriving at P from two coherent sources S and S in 4m while intensity of each wave is I The resultant intensity at P is 21 Find minimum value of S P X 2 x 5 2 3 x 1 1 H S S X P 2 2x 4 x 2

From a water reservoir water is coming out through a vertical conical tube with upper end of radius R and lower end of radius r The length of the tube is I as shown in the figure The velocity of the water entering through the upper end of the tube is ignoring the height of water column in the reservoir 1 2 3 4 3 2 gl R r 1 2 gl R T 1 2 gl R 1 1 gl R 1 R

2 Two identical light metal containers filled with equal amounts of water are placed in a room maintained at a constant temperature 25 C A small metal ball suspended by a thin nonconducting string is submerged into one of the containers Mass of the ball is equal to that of water Both the containers are heated to temperature 40 C and then allowed to cool The container with the ball takes k times longer to cool down to the room temperature than the container without ball Specific heat of water is Sw Specific heat of the material of the ball so is closest to a s ks b s k 1 s s k 1 s d s 1 1 k sw

Consider a spherical shell with inner radius a and outer radius b with uni form charge density as shown in the figure If the total charge is Q calcu late the electrostatic energy UE of this system 6 b

Two capillary tubes of same bore diameter and lengths 1 and 12 are fitted horizontal side by side to the bottom of a vessel containing water The length of a single tube that can replace the two tubes such that the rate of steady flow through this tube equals the combined rate of flow through the two tubes is 1 11 12 2 2 2 2 3 41 h b 21 4

Place the following objects in the HR diagram The sun the pole star Betelgeuse Sirius B Vega Rigel Show discuss and motivate the star placements in a screen recorded video Show your solution and present it with the luminositet 106 104 102 100 10 2 10 4 25 05 BO hertzsprung Russell Diagram Temperatur 1000 K 8 6 10 AO FO GO 5 KO 4 3 MO M8

THE BAR MAGNET The primary origin of magnetism lies in a atomic current and intrinsic spin of electrons b polar and non polar nature of molecules c pauli exclusion principle d electronegative nature of materials Magnetic moment for a solenoid and corresponding bar magnet is a equal for both b more for solenoid c more for bar magnet d none of these Which of the following is not correct about the magnetic field lines a The magnetic field lines of a magnet form continuous closed loops b The tangent to the field line at a given point represents the direction of the net magnetic field B at that point the magnetic field B d The magnetic field lines may intersect to each other in certain conditions Which of the following is correct about magnetic monopole Which of the following relationships between Be and B is correct a B 2 BA c B 4 BA 6 A short bar magnet has a magnetic moment of 0 48 JT The magnitude and direction of magnetic field produced by the magnet at a distance of 10 cm from the centre of the magnet on its axis is a 0 48 x 10T along N S direction b 0 28 x 10T along S N direction c 0 28 x 10 T along N S direction d 0 96 x 10T along S N direction c The larger the number of field lines crossing per unit area the stronger is the magnitude of 8 The magnetic induction at a point 1 A away from a proton measured along its axis of spin is magnetic moment of the proton is 1 4 x 10 26 A m a 0 28 mT c 0 028 mT b 28 m d 2 8 T a Magnetic monopole exist b Magnetic monopole does not exist c Magnetic monopole have constant value of monopole momentum d The monopole momentum increase due to increase at its distance from the field b B 2 B d B 4 Bg 7 A short bar magnet has a magnetic moment of 0 39 I T The magnitude and direction of the magnetic field produced by the magnet at a distance of 20 cm from the centre of the magnet on the equatorial line of the magnet is a 0 049 G N S direction b 4 95 G S N direction c 0 0195 G S N direction d 19 5 G N S direction 9 The pole strength of 12 cm long bar magnet is 20 A m The magnetic induction at a point 10 cm away from the centre of the magnet on its axial line is 4x a 1 17 x 10 T c 1 17 x 10 T 107 Hm m b 2 20 x 10 T d 2 20 x 10 T 5 If Be represents equatorial magnetic field and B 10 Two short bar magnets of magnetic moments m represents axial magnetic field due to a bar magnet each are arranged at the opposite corners of a square

A small block of mass M moves with velocity 5 m s towards an another block of same mass M placed at a distance of 2 m on a rough horizontal surface Coefficient of friction between the blocks and ground is 0 25 Collision between the two blocks is elastic the separation between the blocks when both of them come to rest is g 10 m s collision is electrical and mass of both block is same

X According to equipartition of energy the specific heat capacity of a gas having high molecular weight at high temperature will be very high B may have a small value will have a unique value at all temperatures

Tiny smoke particles in air seen through a microscope as flashes of light when illuminated correctly The irregular movement in it is due to A B D Gravitational attraction between the particles Energy given by light source Continuous bombardment by air molecule Current produced by the lamp used for illumination

A solenoid of cross sectional area 2 x 10 m and 900 turns has 0 6 A m magnetic moment Then the current flowing through it is a 2 24 A b 2 34 mA d 3 33 mA c 3 33 A

Which pair of quantities has dimensions different from the other three pairs O O O O O Impulse and linear momentum Planck s constant and angular momentum Moment of inertia and moment of force O Young s modulus and pressure

A cylindrical plastic bottle of negligible mass is filled with 310 ml of water and left floating in a pond with still water If pressed downward slightly and released it starts performing simple harmonic motion at angular frequency on If the radius of the bottle is 2 5 cm then in close to density of water 10 kg m JEE Main 2019 Jan 1 5 00 rad s 3 3 75 rad s 2 1 25 rad s 4 2 50 rad s

1 38 1 32 and 1 36 the mean value of index with percentage error 1 1 35 1 48 2 1 35 0 3 1 36 6 4 1 36 0 The resistance of a metal is given by R V I where V is potential difference and I is the current In a circuit the potential difference across resitance is V 10 0 5 V and current in resistance I 2 0 2 A The value of resitance in Q with percentage error is 1 5 10 121519007 2 5 15 115 25

The hourly energy requirement of an astronaut can be satisfied by the amount of energy released when 34 g of sucrose is burnt in his body How many grams of oxygen would be needed to be carried in space capsule to meet his requirement for one day 0163 mm B 91 62 cm O C 8 162 gm D 9 162 gm

A circular loop of area 0 5 m and resistance 5 is kept in a region in which a uniform magnetic field exists in direction perpendicular to the plane of the loop The strength of the field increases uniformly from 2 T to 12 T in 0 2 s The heat produced in the loop is O 1J O2J 0 5 J 25

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

In between TA and TB a gas has X B TA TB Tc TD T All molecules have translational as well as rotational motion Some molecules have translational motion and all molecules have rotational motion All molecules have translational motion and same have rotational motion

The air density at Mount Everest is less than that at the sea level It is found by mountaineers that for one trip lasting a few hours the extra oxygen needed by them corresponds to 30 000 cc at sea level pressure 1 atmosphere temperature 27 C Assuming that the temperature around mount Everest is 130 C and that the oxygen cylinder has capacity of 5 2 litre the pressure at which oxygen be filled At site in the cylinder is 3 86 atm 5 00 atm

a Estimate the magnitude of the charges on a comb and a 1 g piece of metal assume the charges to be equal and opposite and located at a point if the comb can just pick up the metal from a distance of 1 cm b How many electrons does this correspond to Ans a 1 04 X10 8 G h 65 x 1019

45 While capturing solar energy for commercial purposes we use 1 Parabolic mirrors 2 Plane mirrors 3 Convex mirrors 4 Concave mirrors

4 A metallic ring is attached with the wall of a room When the north pole of a magnet is brought near to it the induced current in the ring will be S N a a First clockwise then anticlockwise b In clockwise direction c In anticlockwise direction d First anticlockwise then clockwise

Sanatt V 00003070795 In the arrangement shown length of wire AB is 1 m The resistance R is 10 S2 A galvanometer is connected between C and E which shows no deflection for AE 60 cm What is the value of X A E G www BRCX Conducting

The emissivity of human forehead skin is approximately 0 973 Suppose you are in a large room whose wall temperature is 5 3 C during the winter The temperature of air in the room is 25 C and the convection heat transfer coefficient between air and your forehead skin is assumed to be 16 7 W m2 C Assuming no heat transfer from the inner body to the forehead skin determine the surface temperature of the forehead skin in C You may need iteration

1 on a horizontal smooth A trolley T of mass 5kg surface is pulled by a load of 2kg through a uniform rope ABC of length 2m and mass 1kg As the load falls from BC 0 to BC 2m its acceleration in m s changes from 1 20 30 to 6 5 T 20 30 A D B 2 2kg C 20 8 30 8 to

Explain Rayleigh Jeans law with the help of Quantum theories and also show that the number of modes in the frequency range v to v dv in a cubical box of volume V L is 8mV N dv v dv Calculate the number of modes in a chamber of volume 1 m in the frequency range 06 10 4 Hr to 0 61 10 4 He Hr

A bar magnet of magnetic moment M is hung by a thin uniform magnetic field B Work done by the external agent to rotate the bar magnet from stable equilibrium position to 120 with the direction of magnetic field is consider change in angular speed is zero 3MB 2 MB 2 MB

D The range of voltmeter of resistance 300 2 is 5 V The resistance to be connected to convert it into an ammeter of range 5 A is a 12 in series c 0 12 in series b 12 in parallel d 0 1 92 in parallel

2 210 0 g mol 3 90 0 g mol 1 4 15 0 g mol 1 105 0 g mol The vapour pressure of water at 20 C is 17 5 mm Hg If 18 g of glucose C6H12O6 is added to 178 2 g of water at 20 C the vapour pressure of the resulting solution will be 1 15 750 mm Hg 3 17 325 mm Hg 2 16 500 mm Hg AIEEE 2008 3 105 4 17 675 mm Hg

5 The dimensions of a rectangular block measured with an instrument having least count 0 01 cm is 4 0 mm x 10 0 mm x 10 0 mm The maximum percentage error in the measurement of volume of the block is 1 0 45 2 0 045 3 4 5 OF 22 If P 1 3 23 TH CC

10 cm is A column of mercury of length h contained in the middle of a narrow horizontal tube of length 1 m closed at ends The air in both halves of the tube is under a mercury The tube now The distance moved by a 4 5 cm c 2 5 cm 5 cm of vertical of will be b 3 0 cm AIIMS d 1 2 cm 2000 PHYSICY merowly mad

A Young s double slit arrangement with slit width 0 2cm produces interference fringes for red light 6255 A Find the angular fringe separation if the entire arrangement is immersed in water refractive index of the water is 4 3 a b c d Answer N M M N MIT I3 DA

A 5 watt source emits monochromatic light of wavelength 5000 When placed 0 5 m away it liberates photoelectrons from a photosensitive metallic surface When the source is moved to a distance of 1 0 m the number of photoelectrons liberated will be reduced by a factor of 2007 a 8 b 16 c 2 d 4

Explain Stefan Boltzmann law and show that total emissive power of a black body are proportional t the fourth power of absolute temperature A blackbody is placed in an enclosure whose walls are kept 400 K Calculate the rate at which the heat is gained or lost by the body when its temperature is 100 K

0 a The factor of expression 1 are co 1 and co 0 1 If 1 0 i Find the possible values of co and write the real and imaginary roots of c w nj w 0 Where n is positive integer 1 ii Prove that w2n wr 1 w n

a 20 rad s c 8 34 rad s b 10 rad s d 4 5 rad s 2 The gyromagnetic ratio of an electron in sodium atom is a depending upon the atomic number of the atom b depending upon the shell number of the atom c independent of that orbit it is in d having positive value

The figure below shows the path of white light s rays which leave in phase from two small sources S and S and travel to a point X on a screen The path difference is S X S X 10 10 m What wavelength of light give complete destructive interference at X A 40 x 10 7 m B 3 10 7 m C 6 10 7 m D 20 x 10 7 m S

22 Uniform ring of radius R is moving on a horizontal surface with speed v and then climbs up a ramp of inclination 30 to a height h There is no slipping in the entire motion Then h is a v 2g c 3v 2g b v g d v g