Basic Physics Questions and Answers

Q 6 For a diatomic molecule treated as a rigid rotor a Write an expression for the population of the Jth level b Obtain an expression of the most populated Jmax level and sketch N against J at two differ temperatures c Show that at and above room temperatures Erot max KBT

Q 4 A radiation is used to excite the HF molecule Re 2 x10 0 m from J 2 3 level Calculate the moment of inertia rotational constant and energy required for this excitation In the electromagnetic spectrum where does this radiation falls

Q5 Determine the state of the transistor in Fig 28 for the following values of collector resistor i Rc 2 kn ii Re 4 k2 iii Rc 8 kn Vcc 10v VBB 2 7V IB VB Rc Ic Vc B 100 IE VE lkn RE

The position time x t graph shown in the figure is a parabola From this graph we can say that X 36 The body is in uniform motion The body is moving with constant acceleration The body is moving with constant speed The body is not moving at all

A uniform rigid disc of radius R and mass M is free to rotate about an axis on its periphery passing through O as shown in the figure The disc is released from rest at the position shown as blue Calculate the speed of the bottom most point on the dise when it comes to the position shown by dashed lines so that the line tangent to the circle at point O is horizontal Take moment of inertia of the disc about its center of mass Iom MR2 Segtig z cevabin i aretlendi ini g rene kadar bekleyiniz 5 00 Pass Vhot Vhot 1 1 2 3 Rg va Rg

An ideal monoatomic gas of one mole undergoes a cyclic process ADBCA as shown in figure X and Y are two isothermal curves at temperature 211C and 127 Crespectively If the work done by the gas in cyclic process is XR then find the value of X R is the gas constant C B A D Welcome Diganta Saha V

4 The magnitude of torque on a particle of mass 1 kg is 2 5 N m about the origin If the force acting on it is 1 N and the distance of the particle from the origin is 5 m then the angle between the force and the position vector is in radian Main 2019 11 Jan II a c R R M 8 3 b d R 4R O 6

A point object O is kept at a distance of 97cm from thin prism of refracting angle 4 refractive index 3 2 as shown in figure Find distance in cm of point image formed by this prism from O use n 10

7 Block A of mass 2 kg was pressed against a vertical wall with block B of mass 1 kg as shown Coefficient of static friction between all the surfaces in contact is 0 5 The frictional force on A if it is prevented from sliding is a 100N b 50N BK c 19 6N d 9 8N

Read the given passage and fill in the blanks by choosing an appropriate option A mixture of ink having different coloured components is to be separated a i paper is used due to different ii in water of coloured components present in the ink they rise to iii heights The paper with its separate coloured spots is called iv 1 Kroma 2 Chroma 3 Chroma 4 Chromatographic Options 1 1 2 iii iv Volatility Same Kromogram Density Different Chromogram Solubility Different Pigmogram Solubility Different Chromatogram

straight segment OC of length L carrying a current i is placed along y axis Two parallel long current carrying wires are arranged and x a as shown in dig each carry a current i then magnetic force on segment OC is BB 1401 en 2T Holen 4T 2 L a a L a a 12 21 X a 8 x a

m ey if 86 If tube length of astronomical telescope is 105 cm and magnifying power is 20 for normal setting Calculate the focal length of objective 1 100 cm 2 10 cm 3 20 cm 4 25 cm

Question No 2 Figure shows the transfer characteristics of a CE amplifier which of the following is incorrect statement 0 2 V O V 0 6 V At V 0 4 V transistor is in cut off mode O At V 1 V it can be used as an amplifier At V 0 5 V it is in active state At V 3 V it can be used as a switch turned on

Observe the experimental setup carefully You are provided with four types of metallic wires i e gold wire platinum wire lead wire and iron wire Which type of metallic wire would you like to put in the circuit between gap of two terminals A and B so that circuit show maximum conductivity Options Lead Iron Gold Platinum Battery Clips A B Coco Bulb Switch Insert sample to be tested

Single Correct A A If 80 cal heat is extracted from 4 gm ice at 10 C then its final temperature will be B 20 C 40 C 30 C 50 C

A person goes to hospital for the vaccination of covid 19 from his home with uniform speed 20 m s and stayed in hospital for 1 hour and then returns to home 2 with uniform speed of 10 m s If the distance between home and hospital one way is 500 m then average speed and average velocity for entire journey will be respectively 16 0 53 m s zero Zero 0 33 m s 0 33 m s 0 33 m s 0 53 m s 13 33 m s

1 The wavelength of first line of Lyman series is 1215 A the wavelength of first line of Balmer series will be NCERT Pg 421 1 4545 A 3 6563 A 2 5295 A 4 6750 A The rain f the speed of electron in the

i A series circuit consists of a resistance of 1502 an inductance of 0 08H and a capacitor of capacitance 30 F The applied voltage has a frequency of 500 rad s Does the current lead or lag the applied voltage and by what angle 60 65 lead

If 13 6 eV energy is required to separat hydrogen atom into a proton and electr then the velocity of revolving electrom NCERT Pg 4 2 2 2 x 106 m s 4 1 8 x 105 m s 1 1 2 x 106 m s 3 3 2 x 10 m s

a R b R 32 If two planets of radii R and R have densities d and d then the ratio of their respective acceleration Kerala CEE 2013 due to gravity is a Rd Rd 29 1016 6 b Rd Rd d R d R d2 c Rd Rd e R d R d2 un u The weight of an object is 90 kg at the surface of the night equal to half of the

Charge 2 of mass m revolves around a stationary charge q in a circular orbit of radius r The orbital periodic time of 1 4 mr kq 9 92 1 2 4n mr 1 2 would be assume as 2 4 1 4 E kq 9 3 4 mr 4 mr k 2

Graphite and heavy water are two common moderators used in a nuclear reactor The function of the moderator is To slow down the neutrons To cool the reactor To construct wall of reactor To absorb neutrons and stop the chain reaction

ler a spring that exerts the following restoring force F kx for for X 0 F 4kx x 0 A mass m on a frictionless surface is attached to the spring displaced to x A by stretching the spring and released 3 m A The period of motion will be T T 2 k A B The most negative value the mass m can reach will be x 2 C The time taken to move from x A to x A 2 5 D The total energy of oscillations will be kA 3 es straight away will be equal to 5ft 8 Vk

Q 36 Given below are two statements labelled as assertion A and reason R Assertion The resistance of constantan at 100 C is higher than at 27 C Reason The average relaxation time of electrons increases with increase in temperature Select the most appropriate answer from the options given below a Assertion and Reason are true and Reason is the correct explanation of Assertion b Assertion and Reason are true but Reason is not the correct explanation c Assertion c Assertion is true but Reason is false d Both Assertion and Reason are false

ii A long solenoid having 1000 turns per cm carries an alternating current of peak value 1A A search coil having a cross sectional area of 1 x 104 m and 20 turns is kept in the solenoid so that its plane is perpendicular to the axis of the solenoid The search coil registers a peak voltage of 2 5 10 2 V Find the frequency of the current in the solenoid 15 8s

53 A brick has 3 sides a b c a b c can be kept on ground on any face The work required to be done to move slowly from minimum potential energy situation to maximum potential energy situation of brick is 1 mg 3 mg a b 2 2 N 2 b c 2N 2 2 a 2 mg 4 mg 2 2 a c 2 b 2

8 If muonic hydrogen atom is an atom in which a negatively charged muon u of mass about 207me revolve around a proton then first Bohr radius of this atom is radius of electron orbit is 0 53 A NCERT Pg 437 1 2 56 10 10 m 2 2 56 10 11 m 3 2 56 x10 12 m 4 2 56 10 13 m

An object is moving along a circular path with a speed of Points A and B are diametrically opposite Find the change in velocity of the objec between points A and B Options 40 m s Zero 20 m s 20 2m s

The rate of disintegration of a radioactive sample is R at time t and R at time t2 The half life of the sample is proportional to Only one correct answer A B C D t t2 In R R t1 t2 ln R In R t t In R R t1 t Iln R ln R

The radius of a newly discovered planet is roughly 9 times the radius of Earth If both new planet and Earth are considered as perfect spheres then new planet would approximately absorb n Earth in it Find n

3 A furnace is constructed with 200 mm of fire brick 100 mm of insulating brick and 200 mm of building brick with k values 1 4 0 21 and 0 7 W m C The inside temperature is 960 C and outside temperature is 37 C Estimate the heat per unit area total thermal resistance and both the junction point temperature

7 A rope is used to M with a constant downward acceleration of Then power delivered by the rope at any timet Mg t Mg 9 9 1 3 2 Mg t 2 4 20 t of ma Mg t

Consider a point A far away from short dipole By keeping r constant 0 varies from 0 to 360 Variation of potential of dipole at A with respect to 0 is ka A a 360 90 b 0 360 c 0 360 0 d 0 360

my sina 9 A A The angular momentum of a projectile projected at an angle a with the horizontal with speed v about the point of projection when it is highest point is my cos a 9 mv sina cosa Marks 40

A pendulum oscillates with the time period T The string used in the pendulum is stretchable The point to which it is attached is given a positive charge and the bob is also given positive charge q The time period of the pendulum will fo Tsino Teoso ta GE 1 Increase 2 Decrease 3 Remain the same 4 May increase or decrease Asino Proso ing Tuoso q T 2 1 in de 7 TJ ge Sin i

FLO05 9 The velocity of water flowing in a non uniform tu is 20 cm s at a point where the tube radius 0 2 cm The velocity at another point where t radius is 0 1 cm is 1 80cm s 3 20cm s 2 40cm s 4 5cm s

Q2 An n p n transistor at room temperature has its emitter disconnected A voltage of 5 V is applied between collector and base With collector positive a current of 0 2 A flows When the base is disconnected and the same voltage is applied between collector and emitter the current is found to be 20 A Find a I and IB when collector current is 1 mA

The anode voltage of a photocell is kept fixed The wavelength of the light falling on the cathode is gradually changed The plate current I of the photocell varies as follows I 2 K n 1 3 I I 2 2 2 4

94 Minimum and maximum distance should be for clear vision of healthy eye 1 100 cm 500 cm 3 25 cm 100 cm 2 Infinite 25 cm 4 25 cm infinite GO0094 99

point opposite bank of a river flowing at a speed as shown in fig VR Velocity of river with respect to ground VMR Velocity of man with respect to river B 100 3 m k VMR 60 VR 2 m s A Minimum speed relative to water the man should have so that he can reach point B will be 1 in m s Find the value of k

tain mass of an ideal gas is at pressure p and volume V It is compressed isothermally and then allowed to expand adiabatically until its pressure returns to P The gas is then allowed to expand its original volume Upon which of the following p V graphs are these processes correctly shown P a P1 P c P1 V V V PA b P1 P d p V V V

A point source of light S is placed at a distance 10 cm infront of the centre of a mirror of width 20 cm suspended vertica on a wall A man walks with a speed 10 cm s infront of the mirror along a line parallel to the mirror at a distance 20 from it as shown in figure Find the maximum time during which he can see the image of the source S in the mirror f S A B C D 65 3 s 25 15 20cm 10cm 20cm

The angular momentum of a projectile projected at an angle a with the horizontal with speed v about the point of p at the highest point is mv sin a g my cos a g my sin a cosa 2g

In the circuit shown in figure the power which is dissipated as heat in the 60 resistor is 6W What is the value of resistance R in the circuit 6Q www 060 O 10 Q O 130 24 Q R www www 822 12V

1 A carnot s engine whose low temperature reservoir is at 7 C has efficiency of 50 It is desired to increase the efficiency to 70 By how many degrees should the temperature of the high temperature reservoir be increased a 933 K c 373 K b 432 K d 267 K so Joo

ide with f kinetic ith the all the 18 What is the work done by slides down the inclined surface from A to B af the NE 1 32 J 3 8 J B a K ngsin 2 kg 39 u 0 2 4 m A 2 16 J 4 Zero LOOP bod of my 17

The electric field at a distance of 3R from centre on the axis of a ring of charge Q and radius Ris A B 3Q 32 ER 3Q 80R 3Q 40R Zero

R For a constant current the current density electric field and drift velocity are inversely proportional to cross sectional area ol Answer 1 A To a metal wire of diameter d and length L when the applied voltage is doubled drift velocity gets doubled R For a constant voltage when the length is doubled drift velocity will be halved but drift velocity is independent of diameter ol Answer 2

25 Assertion Reason v u at formula is applied for projectile but cannot be applied for uniform circ motion v u at is applicable when an acceleration a is uniform

In Young double slit experiment 1000 nm d 1mm and D 1m If both the slits are havin equal intensities The distance s from central maxima at which intensity is half of maximu intensity is A 12 5 x 10 4 m B 2 5 10 4 m C 7 5 x 10 4 m D 1 25 10 4 m X