Basic Physics Questions and Answers

Fig 2 41 shows a longitudinal cross section of an opti cal fibre made of glass of refractive index 1 68 The pipe is coated with a material of refractive index 1 44 What is the range of the angles of the incident rays with the axis of the pipe for which total reflection inside the fibre can take place 1 00 Fig 2 41 1 44 1 68

In a circuit shown in figure if the internal resistances of the sources are negligible then at what value of R in ohms will the thermal power generated in it be the maximum www R 6 V wwww 30 69 10 V HF

40 A block of mass 2 kg is projected on a rough horizontal surface with momentum 30 kg m s If block stopped after moving a distance 8 m on the surface then coefficient of friction between the block and the surface is 1 1 4 3 0 8 2 0 4 4 0 25

5 A coin is placed at the bottom of an empty hemispherical basin The coin is just invisible to the eye looking over the edge of the basin When the basin is filled with a liquid the whole of the coin becomes just visible to the eye placed at the same position If the radius of the coin is r prove that 4 1 Here is the refractive index of the liquid 1 1 and a is the radius of the hemisphere r a

The emf of Daniel cell gets balanced on 800 cm length of potentiometer wire When a 5 resistance is connected at the terminals of cell then the balancing length become 400 cm The internal resistance of the cell will be ohms

A charged capacitor of capacitance 2C is connected with another uncharged capacitor of capacitance C and an inductor at t 0 as shown in figure The charge on the positive plate of the capacitor of capacitance C when current through inductor will be maximum is found to be 9 Find n the value of n FH C 2C

A body of mass m hangs at one end of a string of length I the other end of which is fixed It is given a horizontal velocity so that the string would just reach where it makes an angle of 60 with the vertical The tension in the string at mean position is 1 2 mg 2 mg 3 3 mg 4 3ma

3 57 The switch S is closed at t 0 The capacitor Cis uncharged but Co has a charge Qo 2 C at t 0 IfR 10002 C 2 F C 2 F E 4V Calculate current in the circuit as a function of time R S Figure 3 403 Co E

2 mg 15 A solid cylindrical body floats along its length in water with half of its height submerged In the same way if it floats with one fourth of height submerged in an oil then the density of oil in g cm is 1 at any cross section of the wire is 14 3 2 6 The accuracy in the 50 cm of a simple 2 4 Medi 4 1 1 2 measurement of length

5 A capacitor is made from two metallic squares plates having side 1 m and at distance 8 85 mm apart The plates are then lowered vertically in to a medium of dielectric constant K 11 at speed of 1 mm s If neglecting resistance of connecting wires the current drawn from the battery during the process is 8 85 x 10 2 farad m 500 V F 1 5 A 3 5 A 8 A uniform chain of length 4 m is kept on a table such that 120 cm hangs freely from the edge of the table The total mass of chain is 2 5 NA mA 4 5 19 8 20 MedicalT

0 A ring of mass m is attached to a horizontal spring of spring constant k and natural length 1 Other end of spring is fixed and ring car slide on a smooth horizontal rod as shown Now the ring is shifted to position B anc released speed of ring when spring attains it s natural length is 1 2 3 200 k 3 lok 3 300 k 2 Vm Rod A lo lllllllllll 8530 B pmmmmmmmmm

13 If the inverse square law of gravitation becomes an inverse cube law of gravitation then the following statements a The planet will have an elliptical orbit b The planet may trace a circular orbit c The path of projectile near the earth surface is parabolic to a greater extent Then the incorrect statement s is are 1 a only 3 b and choply 2 a and b only 17

6 string is 57 07 N Four particles A B C and D are situated at the comers of a square of side d They start moving with same speed v along the sides of square in same sense Then their relative velocity of approach after t d 2v 1 2 3 17 12 A solid cylinder of rou IS 2 Zv 4 0

3 A swimming pool is filled with water up to its brim A swimmer observes a source of light just over the edge of the pool looking from a depth of 2 m in water and at a dis tance of 1 5 m from the vertical wall of the pool The source of the light is placed at a height of 3 m from the ground and at a distance of 4 m from the edge of the pool Find the refractive index of water in the swimming pool

7 In a Young s double slit experiment if there is no initial phase difference between the light from the two slits a point on the screen corresponding to the fifth minimum has path difference 1 2 2 3 9 2 2 10 1 2 2 4 112

s an electron makes transition from an exci ate to the ground state of a hydrogen li com ion 1 Kinetic energy decrease potential ener increases but total energy remains same 2 Kinetic energy and total energy decrea but potential energy increases 3 Its kinetic energy increases but potent energy and total energy decreases 4 Kinetic energy potential energy and to energy decrease

3 5 The top of a water tank is open to air and its water level is maintained It is giving out 0 74 m water per minute through a circular opening of 2 cm radius is its wall The depth of the centre of the opening from the level of water in the tank is close to a 4 8 m b 6 0 m c 2 9 m 2019 Main 9 Jan II d 9 6 m

11 Two identical point charges q of mass m each are suspended through strings of equal length 1 from a common point of suspension Find the charge q if angle subtended by the strings with the vertical is 0 when point charges are in a state of equilibrium

An antenna has a loss resistance of 892 a reactance of 5 2 and a radiation resistance of 75 2 Calculate the efficiency of the antenna and give the answer in to one decimal place

3 26 figure 3 386 illustrates a potentiometer circuit by means of which we can vary a voltage V applied to a certain device possessing a resistance R The potentiometer has a length and a resistance R A voltage V is applied to its terminals Find the voltage V which is fed to the device as a function of distance x Analyses separately the case R Ro Vo AX R Ro Figure 3 386 A

1 71 A solid sphere of radius R is uniformly charged with R charge density p in its volume A spherical cavity of radius 2 is made in the sphere as shown in the figure 1 464 It is given that PR 0 sphere 48V Find the electric potential at the centre C of the

7 The energy required to split 0 nucleus into 16 four a particles is The mass of a particle is 4 002603 U and that of oxygen is 15 994915 U 1 14 43 MeV 3 10 2 MeV 2 6 53 MeV 4 18 4 MeV

The wavelengths involved in the spectrum deuterium D are slightly different from of hydrogen spectrum because 1 Size of the two nuclei are different 2 nuclear forces are different in the two c 3 masses of the two nuclei are different 4 Attraction between the electron and nucleus is different in the two cases

2n h 4 h an electron of energy 11 2 eV undergoes melastic collision with a hydrogen atom in round state Neglet recoiling of atom as m Then in this case 1 The outgoing electron has energy 11 2 2 The entire energy is absorbed by the H a and the electron stop B 10 2 eV of the incident electron energ absorbed by the H atom and electron we come out with 1 0 eV energy 4 None of the above

Please tell the answer fast Find the value of 1 1 e e 1 1 e 1 01 01 201 je e x dx

21 A projectile is fired at 30 with momentum p Neglecting friction the change in kinetic energy when it returns to the ground will be A Zero B 30 C 60 D 100 2 In the above question the change in momentum on return to the ground will be A Zero B 30 D 100 C 60

figure K 4 K Electric field at point P in this situation will be KQ KQ 1 25R 2 9R 2 1 H 41 3 50m 3 KQ 9R 25R 3 4 Data insufficient 11 A long straight thin wire is placed along z axis Wire carry a current along negative z direction Magnetic field at any point P having coordinates 3 4 0 is given by 4 3R H 3 4 50m 5R Hol 31 41 25m H 37 41

A mass falls from a height h and its time of fall t is recorded in terms of time period T of a simple pendulum On the surface of earth it is found that t 2T The entire set up is taken on the surface of another planet whose mass is half of that of earth and radius the same Same experiment is repeated and corresponding times noted as t and T then 1 t 2 T 2 t 2T 3 t 2T 4 t 2T

d 12d 45 models the number of masks m sold as a school fundraiser each day d during the first three weeks of the fundraiser What was the first day that at least 100 masks were sold 100 masks were sold for the first time on the th day

3 T 4 2 5 A particle executing SHM along y axis which is described by y 10 sin phase of particle at t 2 s is 4 1 7 1 ECO 8 2 T 2 4 T Its position at an instant is given by y 7 m sin at vio

According to Bohr s theory of hydrogen ato for the electron in the n allowed orbit the I Linear momentum is proportional to 1 II Radius is proportional to n III Kinetic energy is proportional to 1 n IV Angular momentum is proportional to r Choose the correct option from the codes giv below 1 I III and IV 3 I and II 2 Only I 4 Only III

15 In an atom for the electron to revolve the nucleus the necessary centripetal obtained from the following force exce the nucleus on the electron 1 Nuclear force 2 Gravitational force 3 Magnetic force 4 Electrostatic force 16 Ruther ford model could not explain t

4 If Z A B CDM 2 and percentage error in the measurement of A B C and D are 1 3 2 and 4 respectively then relative error in the calculation of Z will be 1 10 10 1 2 12 x 10 3 1 2 x 10 1 4 10

If heat energy is given to an ideal gas at pressure then select the graph which best represents the variation of VT with temperature 7 VTA VT1 1 3 VT4 T 2 T VTA 4 T

1 III 2 IV 3 I 4 The following diagram indicates the e levels of a certain atom when the system from 4E level to E A photon of wavelen is emitted The wavelength of photon duri transition from E level to E is The will be 9 F 713E 4E E 3 mla 4

1 Based on the table below calculate the probability distribution and the mean value and the most probable value and standard deviation 57 5 7 9 st 23 2 7 7 8 2 6 3 5 3 5 6 a 5 7 3 8 3 6 19 7 2 1 Computational physics lesson series 2 1 Based on the table below calculate the probability distribution and the mean value and the most probable value and standard deviation 5 9 2 2 7895548627 47 3743532 3 365 371 how transcribed image text Computational physics lesson series 2 1 Based on the ble below calculate the probability distribution and the mean value and the most

For a mixture of gases containing n moles of monatomic gas and no moles of diatomic gas The ratio of specific heat at constant pressure and constant volume y C C is given as 3n 5n 1 2 n n 5n 7n 2 2 n n 3 4 5n 7n 3n 5n 7n 5n Fr

the phase of a wave the amplitude of a pulse O the complex amplitude of a harmonic wave the time reference of a pulse Question 11 The electric field of a uniform plane wave is described as E Epe jz Complete the following statements This wave is polarised i Select x z y It propagates in Selec The corresponding magnetic field is in Select direction on direction

are P and Q respectively Then time period of oscillation will be 3 2nQ P Q 2 3 4 14 An electromagnetic wave of wavelength is incident on a photosensitive surface of negligible work function If the photoelectrons emitted from the surface have the de Broglie wavelength then is equal to 1 2mc h 2 h 2mc Q 2 P 2 2nQ P 2mc 2mc EQUIRE

29 Which voltmeter will give non zero reading at resonance R www V 1 Only V 3 Both V and V3 V L oooo V C 2 Only V 4 Both V and V 34

harge is charge 3 65 A charged capacitor is allowed to discharge through a resistor by closing the key at the instant t 0 At the instant t In 4 s the reading of the ammeter falls half the initial value The resistance of the ammeter is equal to in 192 A 0 502 C 202 A C 0 5F HE Figure 3 358 www 252 B 19 D 422

The minimum energy to ionise an atom is the energy required to 1 add one electron to the gaseous state of atom 2 excite the atom from its ground state to its first excited state 3 remove one outermost electron from the gaseous state of atom 4 remove an innermost electron from the gaseous state of atom

54 Figure shows a weight of 30kg suspen ded at one end of cord and a weight of 70kg applied at other end of the cord passing over a pulley Neglecting weight of rope and pulley find the tension in the cord and acceleration of the system g 10ms 1 2 m s 120 N T 2 4 m s 420 N 3 6 m s 180 N 4 4 m s 240 N 30kg T T 70kg

he Bohr model of Atom 1 Assumes that the angular momentum electrons is quantised 2 Uses Einstein s photoelectric equation B Predicts continous emission spectra for ator 4 Predicts the same emission spectra for types of atoms coordin to Bohr por

A block of mass m 25 kg on a smooth horizontal surface with a velocity v 3 ms meets the spring of spring constant k 100 N m fixed at one end as shown in the figure The maximum compression of the spring and velocity of the block as it returns to the original position respectively are 1 1 5 m 3 ms 2 1 5 m 0 ms 1 3 1 0 m 3 ms 1 4 0 5 m 2 ms 1 1 k 0000

4 2 A wooden block floating in a bucket of water has 5 volume submerged When certain amount of an oil is poured into the bucket it is found that the block is just under the oil surface with half of its volume under water and half in oil The density of oil relative to that of water is 2019 Main 9 April II a 0 6 b 0 8 c 0 7 d 0 5 of its

Rain is falling vertically with speed of 15 m s A person is running in rain from east to west with the speed of 5 m s and a wind starts blowing with the speed of 10 m s from west to east The angle with the vertical at which the person should hold umbrella is 1 tan 3 tan 2 3 1 2 2 45 4 tan 1 3

If radius of a nitrogen molecule to be roughly 1 0 then mean free path of nitrogen molecule in a cylinder containing nitrogen at 2 atm and temperature 17 C Molecular mass of nitrogen 28 g is 1 0 10 m 3 5 5 m 2 0 20 m

18 The figure shows a particle experiencing a force as it moves in the presence of a uniform magnetic field directed out of the page What is the charge of the particle A Positive B Negative C Neutral V

32 In the circuit shown there is a box containing a resistance R and inductance L and a capacitor of capacitance C connected in series to an alternating source of angular frequency 4 rad s Box has power factor and the circuit has 3 overall power factor 1 The impedance of the box is 1 3 2 C 4C 4 3