Basic Physics Questions and Answers

The time period of oscillation of a particle whose position varies with time t as x sinot sin2 wot sin4wt is NCERT Pg 344 1 3 53 53 er 8 Pusa Rood 2 4 3 T 4w

3 TR3 xxxx Enhancer 3 A charged spherical conductor having 3 initial charge Q and radius R has a surface density of 0 7 cm When the charge is increased by 0 44 C and the charge density by 0 14 Cm3 If the same charge Q is uniformly distributed over the volume of a sphere of radius R having volume charge density p 3 then a Q 2 2 C p 4 2 Cm b Q 2 2 C p 0 42 Cm 3 c Q 3 3 C p 4 2 Cm

OR How much work is required in turning an electric dipole of dipole mome P from its position of unstable equilibrium in a uniform electrostatic field E

square frame of each side L is dipped in a soap solution and taken out the force acting on e film formed is T surface tension of soap solution A 4 TL B 8 TL C 2 TL D 6 TL

S In a full wave rectifier with central tapping E is the peak voltage between centre tap and one end of the secondary winding The maximum voltage across the reverse biased diode is 1 E 12 0 5 Em 3 2E

5 The simple addition of two vectors having the same initial point is 12 units 6 units is the vector sum between the given two vectors It is given that the resultant of the vectors is at normal to the smaller vector The difference in magnitude of two vectors is

The macroscopic forms of energy are those related to the molecular structure of a system and the degree of the molecular activity and they are independent of outside reference frames Select one True O False

SolveLancer Test How fast is the surface area of a spherical balloon increasing when the radius is 10 cm and the volume is increasing at 15 cm sec SolveLancer Test a 3 cm sec b 2 cm sec c 2 cm sec d 3 cm sec O O b a

Two identical charges q each are placed at a distance 2d A test charge free to move on perpendicular bisector of the line joining the two charges The test charge will feel maximum force when it is at distance from mid point of line joining of charges 1 d 3 2 2 2d 4 d 6 2

30 Two coaxial solenoids of different radii carry current I in the same direction Let F be the magnetic force on the inner solenoid due to the outer one and F be the magnetic force on the outer solenoid due to the inner one then 1 F is radily outwards and F 0 2 F F 0 3 F is radily inwards and F is radily outwards

f the radius of the circular path and frequency of revolution of a particle of mass m are Houbled then the change in its kinetic energy will be E and E are the initial and final kinetic energies of the particle respectively A SE B 15E C 12E D 16 E

0 Suppose a student measures g the acceleration of gravity by measuring the time t for a stone to fall from a height h above the ground After making several timings she concludes that 2h t 1 6 0 1 s and she measures the height h as h 46 2 0 3 ft uses the formula g Then A Percentage error in h is 0 6 B Percentage error in t is 0 063 C Percentage error in g is 13 1 D Final value of g properly rounds is given by 36 5 ft s

respectively with uniform velocities u and v The shortest distance between them is AC L gle right angled at C Two particles start from A and C along AC and CB a a Lv u Lv c u Lu b y u Lu d u In the above problem the time after which the bodies are closest to each other is vL u v b uL v u c u B v u d u

For a liquid moving in a cylindrical tube of radius R and length 1 the pressure difference at the ends of the tube is related by poiseuille s 8nl 871 Q AP law given by For a tube having radius r 2 00 cm 0 01 cm 1 10 0 cm 0 1cm the error in measurement of pressure 2 difference is Take n N s m Q 1 m sec

ype Questions Two particles A and B moving in x y plane are at origin at t 0 The initial velocity vectors o and B are U 81 m s and Up 8jm s Their accelerations are a 21 m s and a 2jm Column I Column II A The time in seconds at which relative velocity of A wrt B is zero B The distance in metetrs between A and B when their relative velocity is zero C The time in seconds at which they have same position D The relative velocity in m s when they are at same position P 16 2 Q 8 2 R 8 S 4

Type Questions Two particles A and B moving in x y plane are at origin at t 0 The initial velocity vectors of and B are U 8i m s and UB 8jm s Their accelerations are a 21 m s and as 2jm Column I Column II A The time in seconds at which relative velocity of A wrt B is zero B The distance in metetrs between A and B when their relative velocity is zero The time in seconds at which they have same position The relative velocity in m s when they are at same position P 16 2 Q 8 2 R 8 S 4

corresponding values at the highest point 27 A helicopter of mass 1000 kg rises with a vertical acceleration of 15 m s2 The crew and the passengers weigh 300 kg Give the magnitude and direction of the a force on the floor by the crew and passengers b action of the rotor of the helicopter on the surrounding air c force on the helicopter due to the surrounding air ith a need of 15 m s gushes out of a tube of

15 A charge particle 1 in S l unit is projected at f 0 with velocity 5 2 m s at an angle of 45 with x direction as shown in a region where uniform magnetic field B 2 2 K Velocity of charge particle at f AY 5 2m s T exist s will be

A Zener diode having breakdown voltage 5 6 V is 147 A magn connected in reverse bias with battery of emf 10 V and a resistance of 100 in series The current flowing through Zener diode is 1 22 mA 2 44 mA 3 56 mA 4 47 mA diode in its proper in mag acting c 1 75 15 8 The p turns select VG

The potential energy U of a particle is given by U 20 x 4 2 J Total mechanical energy of the particle is 36 J Select the correct alternative 1 The particle oscillates about point x 4 m 2 The amplitude of the particle is 4m 3 The kinetic energy of the particle at x 2 m is 12 J 4 All of these

A uniform disc of radius R lies in the x y plane with its center at origin Its moment of inertia about z axis is equal to its moment of inertia about line y x c The value of c can be D none A R 2 B R 2 C R 4

A LED light emitting diode in its proper operation is 1 A heavily doped p n junction in reverse biased 2 A heavily doped p n junction in forward biased 3 A lightly doped p n junction with reverse biased 4 Lightly doped p n junction in no bias nt for the given circuit

4 A uniform solid wheel of mass M and radius r is halted at a step of height has shown in the figure The minimum force F applied horizontally at the centre of the wheel necessary to raise the wheel over this step is h 2r h r h A Mg Ans D B Mg h 2r h r h F C Mg h h r h r h D Mg h 2r h r h

02 Precision in measurement depends on 1 Zero error 2 Parallax 3 Calibration of instrument 4 Least count of instrument usof spherical ball is 1040 4

ELASTIC MODULUS Two wires are made of the same material and hay the same volume The first wire has cross sectio area A and the second wire has cross sectional 3A If the length of the first wire is increased b on applying a force F how much force is needed stretch the second wire by the same amount a 9F b 6F d F c 4F

If Ris the Rydberg s constant of hydrogen The wave number of the second line in the Lyman series will be Regionari ako ng sund OPTIONS MARK FOR REVIEW CLEAR SELECTION O 32 A BR B 9

15 0 55 32 18 24 The electrical circuit used to get smooth output from a rectifier circuit is called gagal una few faga OPTIONS MARK FOR REVIEW CLEAR SELECTION A B C Oscillator dedi Filter heer Logic gates als 12

In a real hydraulic press frictional forces between the piston and the inner surface of tubes cannot be neglected In a particular real hydraulic press shown in the figure piston in the wider arm can stay in equilibrium above the piston in the narrower arm at any height that ranges from h min 1 0 cm to hmax 2 0 cm Density of material of the pistons is n 3 times of that of the fluid used If thickness of the piston in the narrower arm is t 5 0 cm find the thickness of the piston in the wider arm

FINISH D 15 D B A radioactive element A decays into a stable nucleus B Initially a fresh sample purely A is available In the sample of variation in number of nuclei Bwith time is shown by US OPTIONS AB EA al ukrada de al al fou MARK FOR REVIEW CLEAR SELECTION K

Complete the following statement so that it is true To safely work on a temperature measurement apparatus you need to confirm that all electrical supplies are 1 and tagged according to current 2 Caution must be exercised when removing temperature probes because of high or low 3

1 5 5 RACE 01 For the given vector triangle find the following angle 60 90 1 A 1 Angle between A and B 2 Angle between B and C 3 Angle between A and C State whether the following statements are true or false TB B A 30 1 Magnitude of P can be 5 unit 2 N 1 3 Magnitude of any vector is a scalar 4 Unit vectors of parallel vectors are equal The magnitude of a vector cannot be 1 positive 2 unity 3 negative 4 zero A Add vectors A B by triangle law in the following cases B 4 18 158

An electron moves along the line AB which lies in the same plane as a circular loop of conducting wires as shown in the diagram What will be the direction of current induced if any in the loop aga e re e UHET DAA S428ABAB qui a faida kw Q OPTIONS MARK FOR REVIEW CLEAR SELECTION No current will be induced stociquitte

electric dipole is placed at origin with dipole moment directed along positive x axis The direction of electric filed at the point P as shown in the figure will be P 2 2 2 X L 2 3 28 Fou am ar p 1 Along z axis 2 Along negative x axis 3 Along y axis 4 At angle tan 1 1 2 from x axis Three capacitors each having capacitance of

In the given figure if galvanometer shows null deflection then emf of each cell will be 5 V 10 A 2 m 2 9 V 0 9 V A EV 10 m 9 2 B

Q A square and its diagonals are made of a uniform covered wire TH resistance of each side is 1 and that of each diagonal is 1 414 S Determine the resistance between two opposite corners of the square 19 DO A B www 182 1 414 Q2 1 414 22 www 192 D 192 64

5 The four Resistances P Q R and S of a wheat stone bridge are 4 10 20 and 20092 respectively To balance the brige 200 1 Q to be connected in parallel to 20002 3 200 to be connected in series to 2009 3 3 402 to be connected in series to 2002 2

As shown in figure the tension in the horizontal cord is 30 Th weight W and tension in the string OA in Newton are a 30 3 30 b 30 3 60 c 60 3 30 d None of these 30 0 W DPMT 1992 30 N

In a photoelectric effect experiment a point source of light of power 3 2 mW emits photons each of which has 5 eV energy The source is located at a distance of 0 8 m from the centre of a stationary metal disk having a work function of 3 eV The metal disk has a radius of 8 x 10 m Assuming that one photoelectron is emitted for every 106 photons striking the surface of the disk how many photoelectrons are emitted every second A 1 67 x 105 B 105 C 100 D No photoelectrons are emitted from the surface

A 50kW source emits electromagnetic radiation uniformly in all directions The peak strength of the electric field due to this source at a distance of 10 km from the source is A 5 78 x 10 10 N C B 0 123 N C C 0 173 N C D 0 244 N C

In the given diagram choose correct options 10A 6A A The value of I is 4A C Voltage drop across AB is 140 V 552 1052 B 502 1002 YI 552 1022 200V 552 B The current from the cell is 4A D The current from the cell is 10A

If 80 cal heat is extracted from 4 gm ice at 10 C then its final temperature will be 20 C 40 C O 30 C 0 50 C

Starting from rest a car P travels with a uniform acceleration of 2 m s Starting from rest from the same point 4s later a car Q travels with an acceleration of 8 m s in the same direction as P Find the time required by Q to overtake P What is the distance travelled by each car s 64 m A car A is travelling along a straight laval road with a uniform speed of 60 km h It is followed by

The potential energy U of a particle is given by U 20 x 4 23J Total mechanical energy of the particle is 36 J Select the correct alternative O The particle oscillates about point x 4 m O The amplitude of the particle is 4m O The kinetic energy of the particle at x 2 m is 12 J All of these

Two cars P and Q start side by side from rest at the same instant and in the same direction P accelerates uniformly at 4 m s for 10 sec and then moves with uniform velocity Q moves with a uniform acceleration of 3 m s Find the distance between them 30 seconds after start Q is ahead of P by 350 m

In a p n junction diode width of depletion region 1 Increase with decrease in temperature 2 Increases with Increase in temperature 3 Decreases with Increase in doping concentration 4 Both 2 and 3

Example 24 A car hire firm has two cars which it hires out day by day The number of demands for a ca each day is distributed as a poisson s distribution with mean 1 5 Calculate the number of days in a yea which i car is not used ii The number of days in a year on which some demand is refused

Let the angle between two nonzero vectors A and B be 12 resultant be C a C must be equal to A BI b C must be less than A B must be greater than A B c d 10 10 may be equal to A Bl

UNKNOWN RESISTANCE IN METER BRIDGE The resistances in the two arms of the meter bridge are 5 Q and R 22 respectively When the resistance R is shunted with an equal resistance the new balance point is at 1 6 1 The resistance R is a 1092 c 20 S 5 52 www R 2 100 b 152 d 25 92 B

17 Two plane mirrors M and M intersecting at poin O forming an angle of 60 The distance between the two direct images of a point object P formed than by them is 10 cm The distance OP is M ZMAL 1 3 10 20 cm cm 30 30 P TTT M 2 10 cm 4 5 cm

SPECIFIC HEAT CAPACITY The quantities of heat required to raise temperature of two solid copper spheres of rad and r r 1 5r through 1 K are in the ratio 27 a b c 8342 d 54516 3