Basic Physics Questions and Answers

Magnetic field inside a conducting wire is constant with distance from its axis Its value is B 6T i e field is constant at distance r from the axis Then the current density would vary as J Bk Value of the product knB in S I units is Horn

Three resistance P Q R each of 3 0 and an unknown resistance S form the four arms of a wheatstone bridge circuit When a resistance of 60 is connected in parallel to S the bridge get balanced What is value of S 060 0 40 0 30

At the top of a mountain a thermometer reads 7 C and a barometer reads 70 cm of mercury At the bottom of the mountain they read 27 C and 76 cm of mercury respectively The ratio of density of air at the top to that at the bottom of the mountain is 1 3 22 28 32 34 2 4 14 18 75 76

6 A bead of mass m stays at point P a b wire bent in the shape of a parabola y Cx and rotating with angular speed o see figure The value of oo is neglect friction 4 Y 1 2 gC 28 3 0 a b P 2 2gC Vab

The resultant resistance value of three resistors each of r Q are connected in series is x When given three resistances are connected in parallel the resultant value is Ox 0 0 O O 3x

2 13 Two identical strings X and Z made of same material have tension T and T in them If their fundamental frequencies are 450 Hz and 300 Hz respectively then the ratio T is 1 1 25 3 1 5 2 0 44 4 2 25 T Z

Q 15 In a reactor 2 kg of 2U235 fuel is fully used up in 30 days The energy released per fission is 200 MeV given that the Avogadro number N 6 023 x 1026 per kilo mole and 1 eV 1 6 10 9 J The power output of the reactor is close to 1 54 MW 3 125 MW 2 60 MW 4 35 MW

Online Mock Test Series for NEET 2020 28 The current through 10 2 resistor in the given part of an electrical circuit will be 2 V 802 1 18 Vwww 102 43 82 A 692 4 V 2 492 566 8V A 77 ore

Q 17 Train A and train B are running on parallel tracks in opposite directions with speeds 36 km hour and 72 km hour respectively A person is walking in train A in the direction opposite to its motion with a speed of 1 8 km hour Speed in ms of this person as observed from train B will be close to take the distance between the tracks as negligible 1 2 29 5 ms 1 1 30 5 m s

Consider an ideal gas whose particles are subjected to ar uniform external electric field E It is known that the energy of ar electric dipole subject to this field is of the form U pE where p is the dipole moment of each molecule which has the same modulus for all The gas is at an absolute temperature T and has N molecules per unit volume a Determine the average Energy of each Dipole and also find the Polarisation of an Ideal Gas

Two projectiles are thrown from the top of a tower h metre high One projectile is thrown with velocity v 10 m s at angle 0 30 with horizontal at t 0 sec Second projectile is thrown with velocity V 20 m s at 0 30 with horizontal at t 1 sec Minimum separation between the two projectiles is found to be 1 5 x metre Then find out xo Take h 10m g 10 m s 10 30 h metre V 1 1 V 1 0

A plece of wood is floating in water kept in bottle The bottle is connected to an air pump Neglec the compressibility of water When more air i pushed into the bottle from the pump the piece wood will float with 1 Larger part in water 2 Lesser part in wate 3 It will sink 4 Same part in water The maximum force acting on body executin

Two long parallel wires AB and CD carry equal current in opposite direction They lies in the xy planes parallel to the x axis and passes through the point 0 a 0 and 0 a 0 respectively The resultant magnetic field is Zero on the x axis maximum on the x axis Doubled along the z axis at the origin but not other points on the z axis Directed along z axis at all the points on the z axis

When a 20 V m electric field is produced inside a conductor and 4 x 10 A m2 current density is established in it Resistivity of the conductor is O 5 10 40 m O 4 10 30m O 2x 10 0m

3 10 C 4 2016 27 Two metallic spheres of radi n and 2 are separated by a distance d as shown in the figure The capacity of the system is 1 3 4 4 2 44 d 4 4 4 2 195 d d 2 4 4 4RE 5 4 2 d 4

14 A uniform wire of length and mass m is suspended from the ceiling and a block of mass m is suspended at the other end of wire If A is the area of cross section of the wire then 1 Tensile stress at any cross section of the wire 2 mg A is 2 Tensile stress at any cross section of the wire is zero 3 Tensile stress in wire at the point attached to 2 mg A the ceiling is 4 Tensile stress at any cross section of the wire is 2 mg 18 t 19 F

31 In a magnetic field B i yj 3k a charged particle q m is moving with with velocity v 21 3j zk experiences a force F 1 2 k Value of y and z are 1 y 4 z 2 3 y 3 z 6 2 y 2 z 4 4 y 6 z 6

Is 3 m s 19 For a particle executing S H M with amplitude A the position varies with time according to the following graph The corresponding position equation with time is given by B REFEREENEME ME MENEER 1 x A sinot 2 x A B sinot 3 x B A cosot 4 x B A sinot WEW

39 A conveyor belt is inclined at an angle with the horizontal Length of a straight portion of the belt is 1 resistive forces in the belt mechanism are negligible and radii of the end cylinders are negligible as compared to the length 1 Sand falls on the belt with a negligible speed at a constant rate at the top and leaves at the bottom Friction between the belt and the sand is high enough to stop sliding of sand particles almost in no time Inertia of the belt mechanism is negligible as compared to that of the total sand on it Find the steady speed acquired by the belt Acceleration due to gravity is g

10 A butterfly is flying with a velocity 4 2 m s in North East direction Wind is slowly blowing at 1 m s from North to South The resultant displacement of the butterfly in 3 seconds is ons 1 20 m 2 3 m 3 15 m 4 12 2 m

A particle experiences a force F kr f where i is the unit vector along position vector 7 The dimensional formula of K is 1 MLT 3 M L T 2 ML T 2 4 ML T 2 Velocity time graph of a particle in straight line

Questions 100 80 70 60 8 50 40 30 20 10 0 K A 11 212 194 176 158 140 122 104 Y 100 90 g 30 40 5 20 10 0 B 1 212 176 158 140 122 104 5 8 100 K 70 60 30 30 10 9 C 212 194 176 158 140 122 104 100 88 80 70 8 20 10 0 D TIL 212 194 176 158 140 122 104 S 50 32 F 100 8 70 8 E 20 10 O K 212 194 176 158 140 122 104 M 58 50 32 i niya tang walang galang All munda Ang kuwebang ito 1 Which thermometer has the coldest temperature 2 Which thermometer has the warmest temperature 3 Which thermometer shows freezing point 4 Which thermometer has a temperature of 27 C 5 What is the temperature of thermometer E II Directions Tell whether the following statements are true or false If it is true write the word YES and if not write NO Write your answers on the blank 1 Eunice has a fever Her temperature is 30 C 2 The water is boiling Its temperature is 100 C 3 People feel comfortable when the air temperature is 45 C 4 The temperature of a typical summer day is 18 C 5 Water turns to ice when the temperature is 0 C

Choose the correct answer 1 If a 3i 4k and 6 6i 5j 2k then 1 17 3 32 2 27 4 37 14

A particle is projected from a long inclined plane with speed 10 m s in a manner so that time taken by it to fall back to inclined plane should be maximum In this time interval maximum distance of particle from inclined plan least radius of curvature on its trajectory total distance travelled along inclined plane and maximum rate of change of speed are H R d and a respectively Angle of inclination of inclined plane is 0 60 from horizontal g 10 m s Select correct option s A H 10m B R 2 5m C d 40 3 D a 5 m s

33 In the following n p n transistor amplifier circuit B 100 The VCE and VBE of the transistor is 245 KQ 20 A 1 3V 0 1V 3 1V 3V B 5V 1 KQ 2 0 1V 3V 4 1V 0 1V 5 38

Charge Q passing through a cross section of a conductor at any instant is given by Q t 2t C where t is in second Current through the conductor at t 2 sis O 4 A 02A 06 A

A capacitor C is connected to the two equal resistances as shown in figure The ratio of the time constant during in figure What is the ratio of the time constant during charging and discharging of the capacitance is Find the value of k T

3 2 1 6 25 3 25 4 4 5 cn 00 3 An unpolarised beam of light falls on a system of four polaroids which are arranged consecutively in a line such that each polaroid is turned through the angle 45 with respect to the preceding one The percentage of incident intensity stopped by the system is 2 93 75 4 73 25

17 Equation of a plane progressive wave is given by y 1 2cos t 2x If this wave is incident on a denser medium and reflected from it such that amplitude of this reflected wave becomes 1 3 the incident wave then equation of the reflected wave is 1 y 0 4sin t 2x 2 y 0 4sin t 2x 3 y 0 4 os t 2x 4 y 0 4 os t 2x A travelling wave pulse in of

45 Three infinite wires are joined at O as shown in figure If wire 1 carries a current i as shown in figure then net magnetic field at point C will be 1 T JEE Forations 2 SP 3 Ho 2 r 4fr res 8 r

3 A circular plate of radius is cut from one edge 2 of thin circular plate of radius R The moment of inertia of remaining portion about an axis through O and perpendicular to plane of plate is 1 11MR 24 13MR R 2 7MR 12 15MR

4 1 0 2 2 0 3 3 0 6 4 0 4 NI 2 16 The accuracy in the measurement of length 50 cm of a simple pendulum is 1 mm If time period of 2s is determined by measuring the time of 50 oscillations using a watch of resolution 0 2s The percentage error in the determined value of g is

3 24 N 4 32 N The block shown in the figure is in equilibrium Acceleration of the block just after cutting the string will be 1 3g 5 53 2 4g 3 4 o 3 3900 5 4 A particle is displaced from 1 2 m to 0 0 m

A wire of resistance x ohm is drawn out so that its length is increased to three times its original length and its new resistance becomes 36 Q then x will be 080 0 60 040

Test 15 Code A 6 In the arrangement shown in the figure MA MB 2 kg All strings and pulleys are ideal and friction coefficient between blocks A and B is 0 6 Maximum value of horizontal force F that can be applied so that block A does not slip over the block B will be consider horizontal surface smooth 1 8 N A B 2 12 N F

What is the percentage decrease in the weight of a body at the equatorial region of the earth due to its diurnal motion Given radius of the earth 6400 km 2 9 8 0 34

7 A ray of light is incident on a glass slab of thickness t and refractive index in such a way that the reflected ray and the refracted ray are at right angles to each other Calculate the angle of incidence and the lateral displacement of the emergent ray tan 1 11 1 4 1

A charged parallel plate capacitor of distance d has Uenergy A slab of dielectric constant K and thickness d is then introduced between the plates of the capacitor The new energy of the system is given by 1 KU 2 K U 3 Uo U 4 K K

4 A concave mirror is moving with velocity 41 21 cm s1 whereas a point object is moving with 81 11 cm s 1 as shown in figure The object is at a distance of 15 cm in front of mirror whose focal length is 10 cm The axial velocity of image is v then 4x n find the value of n O 15 cm

42 A telescope has an objective of focal length 150 cm and magnifying power 30 The distance between two lenses in normal adjustment will be 1 95 cm 2 145 cm 3 125 cm 4 155 cm

angle 60 with Contal with speed 10 m s The time after times which the speed of the particle remains of its initial speed is 1 5 3 s 3 S 2 WI N S Lo 1 3

By passing all 13 Commonly used collectors in froth floatation method are 1 pine oil III fatty acids a I II and III c I III and IV II coconut oil IV xanthates b II III IV d I II and IV

Identify the most relevant law for each of the following physical situations Select correct choice from the drop down list A solenoid with dc current A charged particle moving in a magnetic fie A plane wave incident on a water surface Choose Gauss law Hertz law Newton s law Snell s law Ampere s law Lorentz force law Choose

A particle of mass 5 m at rest suddenly breaks on its own into three fragments Two fragments of mass m each move along mutually perpendicular direction with speed v each The energy released during the process is 2 1 3 mv 3 a 2 53 4 mv

In the given circuit figure Select the correct option s A the current through the battery is 5A B P and Q are at the same potential C P is 2V higher than Q D Q is 2V higher than P 252 wwww 252 292 www 20V 1 6 02 0 492

3 4 O 2 A solid cylinder of radius R is kept at rest on a smooth horizontal surface A horizontal force is applied to move the cylinder under pure rolling Then height of force from horizontal surface is 1 R 3R 2 A uniform rod 3 2 R 2 4 2R

2 Replace the three forces by a single equivalent force R i e resultant and find its magnitude and direction angle 0 between R and the x axis Present R as a Cartesian vector as well 20 kN 15 F 15 kN X F 25 kN

In the figure shown mass of the plank is m and that of the solid cylinder is 8m Springs are light The plank is slightly displaced from equilibrium and then released Find the period of small oscillations in seconds of the plank There is no slipping at any contact point The ratio of the mass of the plank and stiffness of the spring i e 2 m K 70 mooooooo oooooo

In the figure shown initially switch is open for a long time Switch S is closed at t 0 Potential difference 15V X across resistor R at t 2RCIn2 is found to be R is VZ R Vo 2R 2 Value of x is S www 2C 2R2112 Pet ke l e 1 1 4 3

A charged particle enters into a space and continuous to move undeflected Then in that space A uniform horizontal electric field and a vertical magnetic field may be present A vertical electric field alone may be present uniform electric and magnetic fields both directed vertically downwards may be present A uniform horizontal magnetic field alone may be present