# Basic Physics Questions and Answers

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Basic Physics
Question 17 For a Weston s differential pulley block diameters of pulleys are 26 cm and 24 cm Calculate the velocity ratio 13 26 39
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Two point charges q and q are held fixed at d 0 and d 0 respectively of a x y co ordinate system Then which of the following statement is incorrect O The electric field E at all points on the x axis has the same direction O No work has to be done in bringing a test charge from to the origin O Electric field at all point on y axis is parallel to x axis O The dipole moment is 2 qd along the ve x axis
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Question 20 The area of a semicircle with a diameter of 120 mm will be mm 11309 73 5654 87 3769 91 5026 55
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Solve the following examples 1 How many revolutions does an electron perform before making transition from n 2 to n 1 state in hydrogen atom The average life time of first excited state in H atoms is 108 s R 1 097 x 107 m Ans 8 23 x 10 2 Calculate the wavelength and energy in eV of a photon emitted when in a hydrogen atom an electron makes a transition from the third excited state to the ground state R 1 097 x 107 m c 3 x 108 ms and h 6 625 x 10 34 Js Ans 9 72 x 108 m 12 76 eV 3 Calculate the maximum wavelength of Balmer series in the hydrogen spectrum Calculate the corresponding wave number R 1 097 x 107 m Ans 6563 1 52 106 m 4 The H line in Balmer series of the hydrogen spectrum has a wavelength 6563 From this calculate the wavelength for the first line of the Lyman series Ly Ans 1215
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68 69 70 71 72 73 74 Find the acceleration of a car at t 2s given distance m is defined by S 3t 9t 18 A 24 m s 75 B 24 m s C 36 m s D 18 m s time t of the particle will be equal to zero where t is equal to The position x of a particle varies with time t as x at bt The acceleration at 2a A 76 77 3b C D zero 3b A particle moves along the x axis in such a way that its position coordinate x varies with time t according to the expression x 2 5t 6t Its initial velocity is A 3 ms B 5 ms C 2 ms D 3 ms x 4 sec 0 de A 0 Stane de A log tan 0 B log sec 0 C log cos 0 D log sin 8 The acceleration a in ms2 of a particle is given by a 3t 2t 2 where t is the time If the particle starts out with a velocity v 2 ms at t 0 then find the velocity at the end of 2 s A 36 m s B 1 C t 6t 2 t 3t 2t PARAGRAPH TYPE QUESTIONS C 1 D B 20m s C 18m s D 25m s The acceleration of a particle varies with time t seconds according to the relation a 6t 6 ms 2 Find velocity and position as functions of time It is given that the particle starts from origin at t 0 with velocity 2 ms A 3t 6t 2 t 3t 2t B 31 6t 2 t 3t 2t D 3t 6t 2 t 3t t Paragraph 1 Q No 75 to 77 The position of a body moving along a straight line is given by X 16 t 6t where X is in metre and t in second Find the position of the body at t 1s A 5m B 10 m Find the velocity of the object at any time t A V 16t 12 t 2 B V 16 121 C V 16 12 t Find the acceleration of the body at any time t A 6m s B 2 m s C 10 m s 2 C 15m D 20m D V 12 t D 12 m s 1
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6 7 8 At what temperature will the average molecular kinetic energy in gaseous hydrogen be equal to the binding energy of a hydrogen atom Boltzmann constant k 1 38 x 10 23 JK Ans 1 051 x 10 K Calculate the energy required to remove an electron from Het ion Ans 54 4 eV How much energy in eV should be given to an electron in the level n 2 of a hydrogen atom so that it emit the H line of the Balmer series R 1 097 10 m c 3 x 108 ms h 6 625 x 10 34 Js Ans 2 56 eV
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A screw gauge having 100 equal divisions and pitch of length 1 mm is used to measure the diameter of wire of length 5 6 cm If the main scale reading is 2 divisions and 47th circular division coincides with the main scale Then If pitch 1 M S D then diameter of the wire is 2 47 mm If pitch mm Clear Respo 2 If pitch mm 1 M S D then diameter of the wire is 2 47 If pitch 1 M S D then diameter of the wire is 1 47 mm x2 1 M S D then diameter of the wire is 4 47
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A wire of resistance 4 Q is stretched to twice o its original length The resistance of stretched wire would be 20 40 8Q 16 Q
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An RLC circuit with R 102 is connected across ac source of 200 V and angular frequency 300 rad s When only capacitance is removed the current lags behind voltage by 60 When only inductance is remove the current leads the voltage by 60 The current in the circuit is
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A metal ball hangs from the ceiling by an insulating thread The ball is attracted to a positive charged rod held near the ball The charge of the ball must be C Od B 14 b negative c neutral d positive or neutral e negative or neutral
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Prove that the average value of an A C voltage source is given by V Vsinoot is equal for half period of its cycle The value of the A C voltage of a generator is V 0 volts at time t 0 At time to 2V T t 100 seconds the voltage V 2 volts The voltage keeps on increasing upto 100 volts After that it starts decreasing Determine the frequency of the voltage source
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12 Using the expressions for charge and current for L C oscillator explain L C oscillations 13 Derive expression P Vrms Irms cosd for an A C circuit 14 Using P Vrms Irms cosd discuss the special cases for power consumed in an A C circuit 15 Explain necessity of transformer for power transmission and distribution Solve the following examples 1 Find the necessary inductance if 110 V 10 W ratting bulb is to be used with 220 V A C source having frequency 50 Hz Ans L 6 67 H 2 L 8 1 mH C 12 5 F and R 100 2 are connected in series with A C source of 230V and frequency 500 Hz Calculate voltage across the two ends of resistance Ans 230 V 3 In medium wave broadcast a radio can be tuned in the frequency range 800 kHz to 1200 kHz In L C circuit of this radio effective inductance is 200 H what should be the range of the variable capacitor Ans 88 pF to 198 pF 4 An inductor of 0 5 H and 2002 resistor are connected in series with A C source of 230 V and frequency 50 Hz then calculate 1 Maximum current in the inductor 2 Phase difference between current and voltage and time difference time lag Ans Imax 1 28 A 38 8 and 2 1 ms 73 Alternating Current
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Question 25 The distance of center of gravity for a hemisphere with R as its radius wrt its base is 4R 3 3R 4 3R 8 8R 3
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3 With x axis westward and y axis southward the coordinates of two places are 150 m 200 m and 450 m 600 m The distance between the places is 1 200m 4 1000 2 150m 3 500m A man has to go 50 m due to North 40 m due to east and 20 m due to sout reach a field What distance he has to walk to reach the field 4 zero 1 110 m 2 50 m 3 25 m
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7 In Young s double slit experiment if the distance between two slits is double than the wavelength of light used Prove that a maximum 5 bright fringes will be obtained on the screen 8 In Young s experiment a beam of light of wavelength 6500 and 5200 is used Find the minimum distance from the central bright fringe where bright fringes produced by both the wavelength get superposed The distance between two slits is 0 5 mm and the distance between the slits and the screen is 100 cm Ans 0 52 cm
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In the circuit shown in figure 3 240 switch S is closed at time t 0 Find the current through different wires and charge stored on the capacitor at any time t S 6R www R C 3R
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ply supported beam of span 4m ted to an anticlockwise couple m at the center of the beam reaction at the LHS Left t will be 1 N I
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Q15 Reciprocal of bulk modulus is called compressibility If pressure experienced by certain volume of liquid increases by two times the compressibility becomes O A Compressibility will not vary under pressure O B Decreases by two times O c Increases by two times O D Decreases by half of its original value
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In ultrasonic level sensor Distance between receiver and transmitter is 80m and having flow velocity of fluid is 20m s with velocity of sound 40m s find time taken to ultrasonic waves to travel transmitter to receiver O 1 33s 1s 3 11s O 1 4s
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09 Two positive point charges repel each other with force 0 36 N when their separation is 1 5 m What force do they exert on each other when their separation is 1 0 m O A 0 81 N O B 0 36 N O C 0 24 N O D 0 16 N
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JADHAV TANMAY NITIN Question 21 A machine is said to be ideal when M A V R Efficiency 100 M A V R Can t say
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The Young s modulus of steel is twice that of brass Two wires of same length and of same area of cross section of steel and another of brass are suspended from the same roof If we want the lower ends of the wires to be at NEET 20 same level then the weights added to the steel and brass wires must be in the ratio of 1 4 1 2 1 1 4 2 1 niform pressure n the fractional decreas 3 1 2 Stei
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A current I 10 A flows in a ring of radius ro 15cm made of a very thin wire The tensile strength of the wire is equal to T 1 5N The ring is placed in a magnetic field field which is perpendicular to the plane of the ring so that the forces tend to break the ring The magnetic field in T at which the ring is broken is
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Which of the following expression is correct to determine time period of squar wave generator T 2RCIn Option 2 R1 R2 R2 Anticna R1 R2 R2 RCIn 2RCIn 2R R Option 4 2R1 R2 R2 T 2RCIn 1 Option 1
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An AC source of angular frequency w is connected with a resistance R and an uncharged capacitance C in series The potential difference across the resistor is in phase with the initial potential difference across the capacitor for the first time at the instant assume that at t zero 0 emf is
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An AC Bridge enables us to perform precise measurements for reactance measurement determining the Q factor and frequency measurement An AC Bridge is shown in Figure Q 2 b UNIVE ww DeMux Oscilloscope Channel 2 Rec Figure Q 2 b AC Bridge ADC TITELT
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70 71 72 73 74 30 A particle moves along the x axis in such a way that its position coordinate x varies with time t according to the expression x 2 5t 6t Its initial velocity is A 3 ms B 5 ms C 2 ms D 3 ms 4 sec 0 de 0 Stane do 0 A log tan 0 B log sec 0 C log cos 0 D log sin 0 The acceleration a in ms2 of a particle is given by a 3t 2t 2 where t is the time If the particle starts out with a velocity v 2 ms at t 0 then find the velocity at the end of 2 s A 36 m s B 20m s C 18m s D 25m s The acceleration of a particle varies with time t seconds according to the relation a 6t 6 ms 2 Find velocity and position as functions of time It is given that the particle starts from origin at t 0 with velocity 2 ms A 3t2 6t 2 t 3t 2t C 1 6t 2 t 3t 2t PARAGRAPH TYPE QUESTIONS B 31 6t 2 t 3t 2t D 3t2 6t 2 t 3t t 76 A 0 77 B 1 C 1 Paragraph 1 Q No 75 to 77 The position of a body moving along a straight line is given by X 16 t 6t where X is in metre and t in second 75 D Find the position of the body at t 1s A 5m B 10 m Find the velocity of the object at any time t A V 16t 12 t B V 16 121 C V 16 12t Find the acceleration of the body at any time t A 6m s B 2 m s C 10 m s C 15m D 20m D V 12t D 12 m s 1
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Question 10 A Force of 60 N acting tangentially to a circle of radius 2 m It s moment about diametrically opposite point will be Nm 120 240 30 60
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Wing ratings PIV Peak Inverse Voltage and temperature is true Si diodes have wider temperature ranges and higher PIV than Ge diodes O Si diodes have lower PIV and narrower temperature ranges than Ge diodes Si diodes have lower PIV and wider temperature ranges than Ge diodes OSi diodes have higher PIV and narrower temperature ranges than Ge diodes s The emitter current is always Greater than the base current Less than the base current Less than the collector current equal to the collector current
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A flat dielectric disk lying in x y plane of radius R 1 m carrying charge density o 1 C m is rotating with angular velocity 1 k rad s inside an external magnetic field B 1 1 T It denotes its magnetic dipole moment and torque acting on it then 0 1 rad s 0 1 2 FAm 7 1 7 N m kAm 1 E 4
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Ans LA 24 mH MB 30 HJ There are 1 5 x 104 turns in the winding of a toroidal ring The radius of circular axis of the ring is 10 cm The radius of cross section of ring is 2 0 cm Find inductance of the ring Ans 0 57 HI
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L 8 1 mH C 12 5 F and R 100 2 are connected in series with A C source of 230V and frequency 500 Hz Calculate voltage across the two ends of resistance Ans 230 V In medium wave broadcast a radio can be tuned in the frequency range 800 kHz to 1200 kHz In L C circuit of this radio effective inductance is 200 H what should be the range of the variable capacitor Ans 88 pF to 198 pF An inductor of 0 5 H and 200 2 resistor are connected in series with A C source of 230 V and frequency 50 Hz then calculate 1 Maximum current in the inductor 2 Phase difference between current and voltage and time difference time lag
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2 5 of the total energy of a 100 W bulb is converted into visible light Calculate the average intensity at a spherical surface which is at a distance of 1 m from the bulb Consider the bulb to be a point source and let the medium be isotropic
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jo 0 25 where is the wavelength of the light used obtain the conditions for constructive and destructive interference at point P 7 In Young s double slit experiment if the distance between two slits is double than the wavelength of light used Prove that a maximum 5 bright fringes will be obtained on the screen 0
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If a parallel beam of light of circular cross section having radius 10 mm falls on the surface of glass slab at an angle 30 with the surface of slab then the radius of emergent beam is about O 12 5 mm 15 cm O 14 5 mm O 10 cm
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Assertion A car moving on a horizontal road may be thrown out of the road in taking a turn due to lack of proper centripetal force Reason If a particle moves in a circle describing equal angles in equal intervals of time Then the velocity vector changes its magnitude
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13 Derive expression P Vs Irms cosd for an A C circuit 14 Using P Vrms Irms cos discuss the special cases for power consumed in an A C circuit 15 Explain necessity of transformer for power transmission and distribution Solve the following examples 1 Find the necessary inductance if 110 V 10 W ratting bulb is to be used with 220 V A C source having frequency 50 Hz Ans L 6 67 H
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97 The refractive index of vitreous humor in our eye ball is1 34 Visible light of wavelength ranges from 402 nm to 670 nm as measured in air The wavelength range just approaches retina within vitreous humor is O A 300 nm to 500 nm O 8 340 nm to 540 nm O C 320 nm to 520 nm O D 280 nm to 480 nm
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b 70 3b A particle moves along the x axis in such a way that its position coordinate x varies with time t according to the expression x 2 5t 6t Its initial velocity is A 3 ms B 5 ms C 2 ms D 3 ms x 4 sec 0 d0 71 0 72 Stane do 73 A 0 74 B 1 C 1 C t 6t 2 t3 3t 2t PARAGRAPH TYPE QUESTIONS A log tan 0 B log sec 0 C log cos 8 D log sin 0 The acceleration a in ms2 of a particle is given by a 3t 2t 2 where t is the time If the particle starts out with a velocity v 2 ms at t 0 then find the velocity at the end of 2 s D 22 A 36 m s B 20m s C 18m s D 25m s The acceleration of a particle varies with time t seconds according to the relation a 6t 6 ms 2 Find velocity and position as functions of time It is given that the particle starts from origin at t 0 with velocity 2 ms A 3t2 6t 2 t 3t 2t B 3t 6t 2 t 3t 2t D 3t 6t 2 1 3t t Find the position of the body at t 1s A 5m B 10 m C 15m Find the velocity of the object at any time t A V 16t 12 t B V 16 121 Find the acceleration of the body at any time t A 6m s B 2 m s C V 16 12t Paragraph 1 Q No 75 to 77 The position of a body moving along a straight line is given by X 16 t 6t2 where X is in metre and t in second 75 76 77 C 10 m s D 20m D V 12t D 12 m s 1
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Which of the following is a non conservative force 1 Buoyant force 2 Electric force experienced by a charge kept in a time varying magnetic field 3 Electric force experienced by a charge kept at a distance in front of an unlike stationary charge 4 Spring force
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6 A alone can do a piece of work in 3 days while B alone can do the same work in 2 days If they wor together to complete the work their total wages is fixed X225 Find the share of A RRB 2008 a X 90 b X 75 c X 95 d X 65 e None of the above
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A 2 D 1 B 12 12 C 1 Let the instantaneous velocity of a rocket just after launching be given by the expression v 2t 3t2 where v is in ms and t is in seconds Find out the distance traveled by the rocket from t 2 s tot 3 s sin 2x dx A 32 m B 24m C 15 m D 50m A particle moves with a constant acceleration a 2 ms along a straight line Obtain an expression for its velocity A 2t c B 3t c C 19t c D t c A particle moves with a constant velocity v t 3t 1ms along a straight line Obtain an expression for its displacement A 2t c t 3t 2 1 3t C t c A C D t c 3 2 The acceleration of a particle is given by a t 31 5 where a is in ms2 and t is in second Calculate the displacement of the particle where c d are constants t5 t 5t t t ct d 20 4 t ct d 2 t 5t 20 4 2 B ct d t 3t 2 4 t 3t D 3 2 B t c 20 4 t 31 5t 2 t c
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15 The magnitude and direction of the current in the circuit shown will be 10V 1 a 2 7 3 192 www www 6 92 www 692 C 4V A from a to b through c 29 b A from b to a through c 7 S 3 3 1 A from a to b through c12 01 16 C 1
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C 3 1 If y 3x 2 then find If y 3x tanx then find 6 2x 2x 5 dx 3 3 x dx 1 2 sin x cos x dx uy dx dy dx f sec ec xtanx cosx dx 3 If y 7x 11x 39 find dy dx
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Assertion The tendency of skidding or overturning is quadrupled when a cyclist doubles his speed of turning Reason Angle of bending measured from ground decreases as velocity of vehicle increases
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Kirchhoff s junction and loop laws of electricity are Law of conservation of charge only Law of conservation of energy only Law of conservation of charge and energy respectively Law of conservation of energy and charge respectively
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Choose the correct statement Read More O Internal energy is a path function while heat is not O Heat is a path function while internal energy is not O Both heat and internal energy are not path function
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The power output of an audio system is 18 W For a person to notice an increase in the output Loudness sound intensity of the system what must be the output power must be increased to 11 6 W 0 022 KW 22 68 W 14 2 W
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1 If Y K G are Young s modulus bulk modulus and shear modulus of elasticity respectively and o is Poisson s ratio then which of the following relations is correct 9 1 3 YKG 3 Y 2G 1 o 1 2 Y 3K 1 20 4 All of these
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Two men start from origin at the same time Man A is moving speed V while B is moving towards Y direction with speed 3 V Find out the magnitude of the speed of the Man B with respect to man A A V B 2V C 3 V D None flowing with speed V The speed of swimmer is 3V with respect to river Find moving upstream