Basic Physics Questions and Answers

1 When a conducting loop of resistance 10 C and area 10 cm is removed from externa magnetic field acting normally the variation of induced current in the loop with time is as shown in the figure I in A 0 4 A 0 0 Find the a total charges passed through the loop b change in magnetic flux through the loop 1 0 t in s

1 A 4 kg block is on a smooth horizontal table The block is connected to a second block of mass 1kg by a massless flexible taught cord that passes over a frictionless pulley The 1 kg block is 1 m above the floor The two blocks are released from rest With what speed in m s does the 1 kg block hit the ground 4 kg 1 kg 1 m

5 25 An LR circuit is connected to a battery at time t 0 The energy stored in the inductor reaches half its maximum value at time A R L R In 22 2 L In 2 2 1 B D R L In In L 2 1 2 2 1 2 2

Source voltage of 8V drives the diode in fig through a current limiting resistor of 100 ohm If diode is of silicon and it s forward resistance is 25 ohm the current in circuit is Reverse bias So Net Potential 8 1 25 1 0 0584 A 3 0 08 A ww 10092 8V 1 19 251 125 7 2 0 8 A 0 08 4 zero

6 An ideal massless spring S can be compressed 1 m by a force of 100 N in equilibrium The same spring is placed a the bottom of a frictionless plane inclined at 30 to the horizontal A 10 kg block M is released from rest at the top c the incline and is brought to rest momentarily after compressing the spring by 2 m If g 10 m s2 the speed c mass just before it touches the spring is 10x m s Find value of x S 00000000 30

Light is incident normally on a diffraction grating through which the first diffraction is seen at 32 In this case the second order diffraction will be b at 64 a at 80 c at 48 d there is no second order diffraction

Calculate the equilibrium constant for the reaction 3 2Fe 31 2Fe I3 The standard reduction potentials in acidic conditions are 0 77 V and 0 54 V respectively for Fe Fe and I3 I couples 3 2 a 4 25 10 b d 7 05 105 6 25 107 c 6 25 105

233 A solid spherical conductor has charge Q and radius R It is surrounded by a solid spherical shell with charge Q innerradius 2R and outer radius 3R Which of the following statements is true R 2R 3R i The electric potential has a maximum magnitude at C and the electric field has a maximum magnitude at A ii The electric potential has a maximum magnitude at D and the electric field has a maximum magnitude at B iii The electric potential at A is zero and the electric field has a maximum magnitude at D iv Both the electric potential and electric field achieve a maximum

7 2 a 5 2 A Lb 5 3 2 A c 5 6 A d 5 2 A An alternating current generator has an internal resistance Rg and an internal reactance Xg It is used to supply power to a passive load consisting of a resistance Rg and a reactance X For maximum power to be delivered from the generator to the load the value of X is equal to a zero b X c X d R

loop at A Neglecting in the circuit 5 distance of od at that Ane 5 5 U frame ABCD and a sliding rod PQ of resistance R start moving with velocities v and 2v respectively parallel to a long wire carrying current io When the distance AP 1 at t 0 determine the current through the inductor of inductance L just before connecting rod PQ loses contact with the U frame P D 2v RULY where oooooo Figure 5 332 Hoio In C

of its characteristic spectrum are measured A second fainter characteristic spectrum is also found because of an impurity in the target The wavelength of the Klines are 178 9 pm cobalt and 143 5 pm impurity What is the impurity A B Zinc Copper

A semiconductor material with its fermi energy exactly in the middle of the bandgap of 0 400 eV Calculate the probability to occupy an energy state at the bottom of the conduction band at temperature 300 K and determine the percentage increase in the probability for a temperature rise of 20 K a 5 93 104 57 b 4 36x104 33 c 5 93 104 39 10 4 16

A short bar magnet experiences a torque of magnitud 0 50 Nm where it placed in a uniform magnetic field of 0 25 T at angle of 30 with the direction of field The magnetic moment of the magnet is 2 Am O 3 Am O 4 Am Ave

6 A uniform wire frame of linear mass density 1 having three sides each of length 2a is kept on a smooth horizontal surface An impulse J is applied at one end as shown in the figure P is the midpoint of AB 2a B 2a P The velocity of point P just after the impulse is a b c J a 67 a a 11 d J

5 2 A conducting circular loop of radius a and resistance per unit length R is moving with a constant velocity vo parallel to an infinite conducting wire carrying current io a conducting rod of length 2a is approaching the centre of the loop with a constant velocity v 2 along the direction of the current At the instant t 0 the rod comes in contact with the loop at A and starts sliding on the loop with the constant velocity Neglecting the resistance of the rod and any self inductance in the circuit find the following when the rod slides on the loop a The current through the rod when it is at a distance of a 2 from the point A of the loop b Force required to maintain the velocity of the rod at that instant 10 ns a i 9vololo 16aRn a 3 P In 3 b 10 a 10 2 Figure 5 330 Holo Vo 32aRT A 40 In 3 A 5 11 V C J

13 18 3 M M P 4 M M H XX X wwwwwwwww M moved with a constant speed v towards left The complete circuit is placed in a uniform magnetic field B perpendicular to the plane of the circuit inwards The current in HKDE is Space For Rough Work 1 Al A t 2 A A 3 A A GTS 47 P 2 XXIII VIII 20

component in the infinite network shown in figure ha resistance R 42 A battery of emf 1 V and negligible inter resistance is connected between any two neighboring poin say X and Y R www R R R R R R R I I wm I ww ww I RR R R R RR R wwwww R R www R R wwwwwww R R RR RR wwwwwwww www TX Y RR R www R R wwwwwww R R R R R R R R R R R R www R R www R R www www ww 1 R

Calculate the capillary rise in a glass tube of 2 mm diameter when immersed in 03 a water b mercury Both the liquids being at 20 C and the values of the surface tensions for water and mercury at 20 C in contact with air are respectively 0 0075 kg f m and 0 052 kg f m

11 106 Gravitational potential energy of a body on the surface of earth is E Its potential energy at distance R 2 from the centre of earth is R radius of earth 8 1 E 11 3 8 E 2 E 4 0 5 E

A wave is represented by the equation y a sin kx t is superimposed with another wave to form a stationary wave such that the point x 0 is a node Then the equation of other wave is 1 y a cos kx oot 3 y asin kx ot 2 y acos kx ot 4 y a sin kx wt

Determine X Y for the shaded area R 3 fx R 3 Circl Your answer Typed answers are easier for students to read than handwritten notes BIU A A 2

23 A parallel plate capacitor of capacitance C has spacing d between two plates having area A The region halinded between the plates is filled with N dielectric layers parallel to its plates each with thickness 8 The TH N For a very large N 103 the capacitance C is m dielectric constant of the mth layer is K K 1 m N K A d In 2 is the permittivity of free space O The value of a will be JEE Adv 2019 Paper 1

4 25 5 A body of mass 2 kg travels according to law x at bt ct where a 3 m s b 4m s and c 5 m s then force 15 2 kg and fax forex at bt c a 3 m s b 4m s en c 5 m s t t 2s acting on body at t 2 s for an t 1 68 N 2 136 N 3 272 N 4 336 N 1 68 N 2 136 N 3 272 N 4 336 N

A horizontally oriented bent thin tube ABC of length 1 4 m rotates with a constant angular velocity about a stationary vertical axis OO passing through the end A as shown in figure The portion BC of tube is parallel to OO and its length is equal 0 4 m At t 0 AB part of tube is filled with an ideal fluid The end A of tube is open the closed end C has a very small orifice Find the maximum height i m reached by fluid relative to end C take g 10 s and 10 rad s 1m A 0 4m B

Find the expression for the electron s resonance frequency using F ma equation in which 4 P the polarization is P ner and the depolarization field would be E 3 a a b a c d o 2 Ane 3m 4 m 4 ne 3m 2 ne 2m

22 Using the lens formula show that an object placed between the optical centre and the focus of a convex lens produces a virtual and enlarged image

There is a bicycle on a bicycle stand We know that its rear wheel s moment of inertia around its axis is I 0 5 kg m and its radius is r 30 cm We speed up the wheel by repeatedly hitting it with a hand tangentially on its circumference in the direction of its rotation The speed of each hit in the rest reference frame is v 5 m s the mass of the hand is m 1 5kg the hand loses all its velocity in the reference frame of the point of impact after the impact the hand is moving around an elbow but we neglect rotation of the forearm If velocity of a point on the perimeter of then value of a 2B yl 10 a 9 the wheel after 10 hits be v a 1

iv Give scientific reasons for the following a Wires are made of copper and aluminium b Food items rich in calcium must be eaten regularly VI Distinguish between the following

In a Young s Double slit experiment first maxima is observed at a fixed point P on the screen Now the screen is continuously moved away from the plane of slits The ratio of intensity at point P to the intensity at point O centre of the screen a remains constant b keeps on decreasing e first decreases and then increases d First decreases and then becomes constant

A vessel with water is placed on a weighing pan and it reads 600 g Now a ball of mass 40 g and density 0 80 g cm 3 is sunk into the water with a pin of negligible volume as shown in figure keeping it sunk The weighting pan will show a reading Weighing pan 600 g 550 g 650 g

A 72 0 g block carrying a charge Q 31 0 C is connected to a spring for which k 80 0 N m The block lies on a frictionless horizontal surface and is immersed uniform electric field of magnitude E 4 74 x 10 N C directed as shown in the figure below The block is released from rest when the spring is unstretched x m Q www x 0 E 2 a By what maximum distance does the block move from its initial position 14 08

5 43 In the circuit arrangement shown in figure 5 346 the switch S is closed at t 0 Find the current in the inductance as a function of time Does the current through 1002 resistor vary with time or remains constant S 1002 www HH 36V 502 ImH releell Figure 5 346 Ans 3 6 1 e A where t 300 s Current through 1022 resiste varies with timel

In a double slit experiment at a certain point on the screen the path difference between the two 1 interfering waves is th of a 8 wavelength The ratio of the intensity of light at that point to that at the centre of a bright fringe is

A sound source S emitting a sound of frequency 500 Hz and receiver R of mass m are at the same point R is performing SHM with the help of a spring of force constant k At a time t 0 R is at mean position and moving toward right extreme position as shown in figure At the same time source starts moving away from the R with an acceleration 18 75 m s Find the frequency in Hz registered by receiver at a time t 10 s Given that amplitude of oscillation of R m Vsound 300 m s y Lx R M K M 150 TT 100 772 9

pot Light of wavelength 4300 A is incident on a nickel surface of workfunction 5 eV and b a surface of workfunction 2 3 eV Find out whether electrons will be emitted and if so the mas velocity of the emitted electrons in each case

Calculate the potential energy of a metallic shell of radius R carrying a charge q Calculate the work required to increase the radius by dR Hence calculate the electrostatic pressure on the shell A a metallic shell of radius R is carrying a charge a Calculate the electrostatic force due to a

A beam of light has a small wavelength spread about a central wavelength The beam travels in vacuum until it enters a glass plate at an angle relative to the normal to the plate as shown in the figure The index of refraction of the glass is given by n 2 The angula spread of the refracted beam is given by 80 1 82 A 60 C 80 12 60 B 60 D 50 Vacuum Glass dn 2 d tan dn 2 11 d2 82

5 19 A box P and a coil Q are connected in series with an AC source of variable frequency The EMF of source is constant at 10V Box P contains a capacitance of 1 F in series with a resistance of 3292 Coil Q has a self inductance 4 9mH and a resistance of 68 The frequency is adjusted so that the maximum current flows in P and Q Find the impedance of P and Q at this frequency Also find the voltage across P and Q respectively Ans P 76 9652 Q 97 590 P 7 6V Q 9 8V impedance 10092

At point A 0 0 4 a positive charge Q is located and at point B 0 0 4 a negative charge of magnitude Q is located Calculate the direction of the electric field intensity at point C situated at 5 0 0 a z direction b z direction c x direction d y direction

A car is moving in a spiral starting from the origin with uniform angular velocity What can be said about the instantaneous velocity O O O O It increases with time It decreases with time It remains constant It does not depend on time

When creating a polar array entering a negative angle to fill a Will copy objects in a clockwise direction b Will copy objects in a counterclockwise direction c Is not allowed d None of the above

An electron and proton enter a magnetic field perpendicularly Both have same kinetic energy which of the following is true O Trajectory of electron is less curved O Trajectory of proton is less curved O Both trajectory are equally curved O None of these

p n junction diode under forward bias is shown below Correct diagram for barrier potential is 1 2 3 P 4 None of these 11 V V V V V V V V V

A proton of mass 1 67 x 10 27 kg and charge 1 0 10 19 C is projected with a speed of 2 x 106 m s a an angle of 60 to the x axis If a uniform magnetic field of 0 104 T is applied along y axis the path of proton is helix with circular radius 0 2 m radius 0 1 m radius 0 5 m radius 0 7 m

According to the fine tuning argument living systems are irreducibly complex there may be many universes with different parameters than ours consciousness is inexplicable if God does not exist few possible values of the constants of physics are life permitting

2 In the diagram shown assume the pulley is smooth and fixed all surfaces are smooth and the ropes are massless The mass of each block is marked on the block in the diagram Assume g 10 m s and sin37 0 6 sin 53 0 8 Find the magnitude of acceleration of the 8M block immediately after the system is released from rest 2M

and oid vith the 5 33 An inductor of inductance L 400mH and resistors R 20 and R 202 are connected to a battery of EMF E 12V as shown in the figure 5 341 The internal resistance of the battery is negligible The switch S is closed at time t 0 What is the potential drop across L as function of time After the steady state is reached the switch is opened What is the direction and the magnitude of current through R as a function of time E S www R reeeeee L R

A charge q is placed inside an uncharged hollow metallic shell of radius R Prove that the charge induced at the outer surface is uniformly distributed

A small conducting loop of radius r resistance R is pulled with velocity v perpendicular to long straight current carrying conductor carrying a current If the power dissipated P in the loop is constant find the variation of the velocity of the loop with the displacement x R X m given x r

Four arms of wheat stone bridge have the AB 60 2 following resistances BC 100 CD 60 DA 12 Q A galvanometer of 15 2 is connected across BD Calculate the value of additional resistance connected across CD to balance NCERT Pg 119 the bridge A 1 122 10 60 Q 12 Q B 100 Q G 15 Q D 60 Q 2 15 Q C