Basic Physics Questions and Answers

Two particles of mass 5 kg and 10 kg respective are attached to the two ends of a rigid rod of leng 1 m with negligible mass The centre of mass of the system from the 5 particle is nearly at a distance of 1 80 cm 3 50 cm 2 33 cm 4 67 cm

13 For the given circuit of p n junction diode which of the following statement is correct R wwww a In forward biasing the voltage across R is V vlh b In forward biasing the voltage across R is 2V c In reverse biasing the voltage across R is V d In reverse biasing the voltage across R is 2V

A positively charged particle enters in a uniform magnetic field with uniform velocity v If angle between velocity and magnetic field is 180 the trajectory will be Straight line Circular O Helical Elliptical

A cell of constant e m f first connected to a resistance R and then connected to a resistance R If power delivered in both cases is equal then the internal resistance of the cell is 1 R R 3 R R 2 2 4 R VR R R 2

Q1 In a Young s double slit experiment the slits are separated by 0 28 mm and the screen is placed 1 4 m away The distance between the central bright fringe and the fourth bright fringe is measured to be 1 2 cm Determine the wavelength of light used in the experiment

2n 2n 1 73 A particle located at x 0 at time t 0 starts moving along the positive x direction with a veloc v that varies as v a x The displacement of the particle varies with time as a t b 2 11 c t d t fogly from the top of a tower It COV cond before

1000 small water drops each of radius r and charge q coalesce together to form one spherical drop The potential of the bigger drop is larger than that of the smaller one by a factor A B C D 1000 100 10 1 Correct Answer My Answer

Two spheres of radii 2 cm and 3 cm are charged to same potential If 01 and 02 be respectively the values of surface charge density on the conductors then the ratio 1 will be 02 A B C 69 2 3 2 32 2 Correct Answer

A semicircular wire of radius R carrying current i is placed in a magnetic field Bo on left and 2B on right of YY as shown in the figure The magnetic force experienced by wire is X X X Bo X X X X X Y xix X X X R X X X X X 2Bo XX

Question 30 A The work required to put the four charges from infinity to the position shown here is q a B 0 65q TEQa 1 0q T M M 4 00 9 q N M 1 00 a Correct Answer

Position in m of a particle varies with time in s as x 21 The instantaneous velocity at 2 sis t 1 12 m s 3 24 m s 2 10 m s 4 16 m s

8 Velocity of a particle moving in a straight line changes from 20 m s to 60 m s in 20 s The average acceleration of the particle is 1 10 m s 2 1 m s 3 2 m s 4 3 m s

The activity of a certain radioactive sample is plotted against time in a graph If the initial slope of the curve is m then slope of the curve at point B is fc Activity 0 f t B 0 m O2m Elo time

8 If the mass of the body is doubled the kinetic energy will be a Same b Halved c Doubled 9 Force applied on a wall of the room results in a Negative work done 10 Rate of doing work is known as a Energy b Power b Zero work done c Density d Four times c Both a and b d None of these d None of the

PLZ PROVIDE A DETAILED HE QUESTION B and C are two identical spheres kept in contact with each other on a horizontal frictionless floor Another identical sphere A moving with velocity u along the common tangent to B and C strikes B and C simultaneously B A 68 C pollici Find their velocities after collision if a Collision is elastic b Collision is inelastic with coefficient of restitution e PLETE

26 Two bodies A of mass 1 kg and B of mass 3 kg are dropped from heights of 16 m and 25 m respectively The ratio of the time taken by them to reach the ground is 4 1 3 12 5 4 5 12

5 A particle starts its motion from origin and returns back to origin after 10 s The average velocity of particle is 1 10 m s 2 20 m s

19 180 O 85 m An object travels a distance of 40 m during last two seconds of its fall when it dropped from top of a tower The height of the tower is g 10 m s 75 m 80 m Mark for Review 45 m 02 40 hr min

50 Figure shown a part of a bigger circuit The capacity of the capacitor is 6 mF and is decreasing at the constant rate 0 5 mF s The potential difference across the capacitor at the shown moment is changing as follows dV di 2V x d V 1 di 2 m 2H 40 The current in the 4 52 resistor is decreasing at the rate of 1 mA s What is the potential difference in mV across the inductor at this moment

8 If the distance travelled by body is 6 0 0 3 m in time 2 0 0 1 s Then the speed of body with error limits is 1 3 0 0 15 m s 2 3 0 0 20 m s 3 3 0 0 3 m s 4 3 0 0 4 m s

Question 32 A A charge Q placed at the centre of a metallic spherical shell with inner and outer radii R and R respectively The normal component of the electric field at any point on the Gaussian surface with radius between R and R will be B C Zero Q 4TR Q 4 TR 2 M M 4 00 Q N M 1 00 Correct Answer My Answer

gardener holds a pipe of uniform inside cross sectional area 3 60 cm The opening at the nozzle has cross sectional area 0 250 cm Water velocity in the segment of the pipe that lies n the ground is 48 0 m s From the nozzle water comes out and falls on to a plate moving normally towards the discharging jet of water at a speed of 2 80 m s Assume water does not plash after hitting the plate rather it drips down staying in contact with plate Find the force on the plate due to the jet Density of water is 1000 kg m and g 10 m s 3 60 cm h 0 250 cm

10 10 points A convex lens has focal length f 0 5 m If you place a letter before the lens you can see an image of this letter on a screen behind the lens and the image is 2 times the size of the letter 1 Is this image erected or inverted 2 Where should you place the letter and the screen

The hollow shaft is than a solid shaft of same mass material and length 1 less stiff x2 more stiff 3 equally stiff

Calculate the value of the heat of vaporization of ice at 1 C The values of the pressure of water vapor are 3 88 mm Hg at 2 C and 4 58 mm Hg at 0 C

Three charges 91 92 and 93 are placed as shown in the figure The x component of the force on 9 is proportional to A B 92 b 92 b 93 a 93 YA 9323 sine M M 4 00 q COS 0 b q2 X My Answer Correct Answer

Question 23 A particle of mass m and charge q is thrown from a point in space where uniform gravitational field electric field are present The particle 9 m A B g A May follow a straight line B May follow a circular path C May follow a parabolic path C 0 M M 4 00 A B are correct A C are correct B C are correct u N M 1 00 E Correct Answer My Answer

26 An inductor L and a resistor R are connected in series with a direct current source of emf E The maximum rate at which energy is stored in the magnetic field is E 4R A B R C 4E R D 2E R

115 Three identical smooth cylinders each of mass m and radius r are resting in equilibrium within a fixed smooth cylinder of radius R only a part of this cylinder has been shown in the fig Find the largest value of R in terms of r for the small cylinders to remain in equilibrium

An object is thrown along a direction inclined at an angle of 45 with the horizontal direction The horizontal range of the particle is equal to MP PMT 1985 a Vertical height b Twice the vertical height c Thrice the vertical height d Four times the vertical height

4 Motion remains simple A short bar magnet of magnetic moment 1 414 Am lying in a horizontal plane with its north pole pointing east P is a point at a distance 10cm from the centre O of the magnet The line OP makes an angle 0 tan 2 with the magnet Horizontal component of earth s magnetic field is 0 3 x 10 4 T The net horizontal magnetic field is 1 2 104T 3 17 x 104T 2 2 3 104 T 4 1 4 104 T

The line graph in the above figure shows the sales of scooters and bike by the startup company In which year the increase in combined sales of both the vehicles was maximum Production In thousands 70 60 50 40 30 2002 03 2003 04 2004 05 2005 06 2006 07 Scooter RiL

denti Electrostatic field at the surface of a charged conductor is proportional to the surface charge density There is no net charge at any point inside conductor when a charge is placed outside it O Inside charged or neutral conductor electrostatic field is zero The electrostatic field at surface of charged conductor must be tangential to surface at any point when placed in external electric field

A metallic disc of radius r is made of a material of negligible resistance and can rotate about a con ducting horizontal shaft A smaller non conducting disc of radius a is fixed onto the same shaft and has a massless cord wrapped around it which is attached to a small object of mass m as shown Tw ends of a resistor of resistance R are connected to the perimeter of the disc and to the shaft by sliding contacts The system is then placed into a uniform horizontal magnetic field B and the mass m is re leased Find the terminal angular velocity with which the disc will rotate finally Take r 10cm a 2cm R 50 gm g 10 m s2 R A 200 rad s C 100 rad s 1 100 22 B 0 2 T m a m B 300 rad s D 10 rad s

The surface density of charge on the surface of a charged conductor in the air is 26 5 Cm 2 Then the outward force per unit area of the charged conductor is A B C D 3 5 N m 17 7 N m 8 85 N m M M 4 00 39 7 N m My Answer Correct Answer

Q 8 A particle located at x 0 at time t 0 at time t 0 It starts moving along positive x direction with a velocity v a x The displacement of the particle varies with time as AE A t C 12 B t D 1 t

Self induction coefficient of a coil can be increased b a Increasing current through it b Decreasing current through it c Inserting an iron rod in the coil d Increasing number of turns a and c only O a c and d only c and d d only

Consider a planet in solar system which has mass double to mass of earth and density equal to average density of the earth An object weighing won the earth Then its weight or the planet surface will be Ow 2w w 2

108 Three small discs are connected with two identical massless rods as shown in fig The rods are pinned to the discs such that angle between them can change freely The system is placed on a smooth horizontal surface with discs A and B touching a smooth wall and the angle ACB being 90 A force F is applied to the disc C in a direction perpendicular to the wall Find acceleration of disc B immediately after the force starts to act Masses of discs are m m mg 2 m mc m wall is perpendicular to the plane of the fig A wall m 2m 90 m C LL F

A galvanometer coil has resistance of 15 Q and meter shows full scale deflection for a current of 5 mA In order to convert the meter into a voltmeter of range 0 to 10 volt the resistance in series required is O 1795 Q O 2285 0 O 14550 O 1985 0

Two resistances of value R 10 00 2 and R 5 2 2 are connected in series The effective resistance in series with appropriate significant figures is 1 15 02 3 15 37 2 2 15 20 4 16

2 15 2 2 4 16 2 ce occupies a volume of 1 60 substance with appropriate 2 4 0 g cm 12 The resistance R where measured value of potential difference V 100 5 volts and current i 10 0 0 1 A The maximum percentage error in resistance is 1 5 3 8 2 6 4 10

2 4 0 g cm 4 4 000 g cm la of universal gravitational 2 M L T 4 LT 2 1 5 3 8 13 If the random error in 10 observation is x then the random error in 50 observation is 1 X 2 3 x 4 5x 3 2 6 4 10 X5

wer ificant zeros in measured 2 2 4 4 r 2 375 to three significant 10 Pressure on a square plate is measured by measuring the side of plate and force on the plate The maximum percentage error in measurement of force is 4 and that of side length is 2 Then maximum percentage error in pressure is 1 8 3 2 2 6 4 1

2 2 37 4 2 38 value R 10 00 2 and R ed in series The effective with appropriate significant 3 2 4 1 11 The initial and final temperature recorded in an experiment are 20 5 0 3 C and 50 5 0 2 C The rise in temperature with error is 1 30 0 0 2 C 2 30 0 0 8 C 4 30 0 0 1 C 3 30 0 0 5 C

If the error in the measurement of radius of sphere is 2 then the error in the determination of volume of sphere is 1 1 3 6 2 3 4 12

1 527 with regard to 2 1 82 4 1 8 a P 2 V b RT P is V 3 ML T 4 M L T 16 If pressure P velocity v and time T are taken as fundamental physical quantities Then the dimensional formula of force is 1 Pv T 2 P T 2 3 PvT 4 Pv T If unit of mass is assumed as 10 kg unit of length 17

An electron accelerated through a potential difference V passes through a uniform transverse magnetic field experience a force F If the accelerating potential increase to 4 V the electron in the same magnetic field will experience a force OF 2F 2F

A light uniform rod of 3 m length is pivoted at one of its ends and a small sphere of mass 0 5 kg is attached at the other end as shown in the Figure The rod with the sphere is at rest in the horizontal plane with two attached springs S and S each of spring constant 1000 Nm The time period of small oscillation of the sphere about the pivot O is in ms O O O O 30m 60m 40m 20m 1m 8 Im 0 5 kg

A vertical cylinder contains an ideal gas enclosed at a pressure of 2 atmospher e by means of a freely moving piston c ontaining weights The cylinder is place d on a lift which rises with an accelerati on of g 3 The fractional change in volu me of the gas is Does the gas gets co mpressed