Basic Physics Questions and Answers

The output of the given circuit in figure shown R www V Will be zero for all time Is Half wave rectified with Positive cycle in output Is Half wave rectified with negative cycle in output Is full wave rectified

O Single Correct MCQ A student measured the length of a rod and wrote it as 3 50 cm Which instrument did he use to measure it A B C D A screw gauge having 100 divisions in the circular scale and pitch as 1 mm A screw gauge having 50 divisions in the circular scale and pitch as 1 mm A meter scale A vernier calliper where the 10 divisions in vernier scale matches with 9 division in main scale and main scale

wind turbine has 12 000 kg blades that are 9 m long The bladen spin at 23 rpm Part A If we model a blade as a point mass at the midpoint of the blade what is the inwe force necessary to provide each blade s centripetal acceleration Express your answer with the appropriate units F 1 29 106 Submit N

ray comes to the first mirror reflects and hits second mirror If this ray turns back on itself after reflecting from the second mirror find the focal point of the second mirror 3 1 1 01 2 16 3 2 2 2m 6m A 1m f 3m TTTT 6m II LLL f B 2m D 6m 6

O Single Correct MCQ A bob of mass m attached to an inextensible string of length is suspended from a vertical support The bob rotates in a horizontal circle with an angular speed rad s about the vertical About the point of suspension A B C D angular momentum changes in direction but not in magnitude angular momentum changes both in direction and magnitude angular momentum is conserved angular momentum changes in magnitude but not in direction

The I V characteristics for two semiconductor devices are shown in figure A V Volt A a The corresponding devices are LED Solar cell LED Photodiode Photodiode Solar cell Photodiode Zener diode b V

m st e viii A train is targeted to run from Delhi to Pune at an average speed of 80 kph but due to repairs of track looses 2 hrs in the first part of the journey If then accelerates at a rate of 20 kph till the speed reaches 100 kph Its speed is now maintained till the end of the journey If the train now reaches station in time find the distance from when it started accelerating TRA0 Im

If 0 is instantaneous angle which joining the particle and the centre of the loop makes with the vertical as shown then identify the correct statement s related to the normal reaction N between the block and the surface A The maximum value N occurs at 0 0 5R B The minimum value of N occurs at 0 for H 2 C The value of N becomes zero at 0 for all H 5R D Minimum value of H to complete vertical circular motion is 2

A parallel plate capacitor is made of two circular plates separated by a distance of 5 mm with a dielectric of dielectric constant 2 2 between them The electric field in the dielectric is equal to 3 104 V m 1 The charge density of the positive plate is close to A B 3x 104 Cm C 6x 104 C m 2 C 6x 10 7 Cm 2 2 C

A 24 V battery is connected in series with a resistor and an inductor with R 7 0 2 and L 7 8 H respectively a Find the energy stored in the inductor when the current reaches its maximum value J b Find the energy stored in the inductor one time constant after the switch is closed J

1 20 kgf 3 70 kgf 2 40 kgf 4 140 kgf If spinning speed of the earth is decreased then weight of the body at the poles 1 Does not change Decreases 3 Increases 2 4 May increase or decrease

in series The separation between them and relative orientation is fixed and once they are connected in configuration A and then in configuration B as below mrrrrrrrrr ooooooo A morrrrrrrolllllll B If the maximum and minimum equivalent inductance reeeeeee

the correct statements a Average speed of a particle in a given time is never less than the magnitude of the average velocity du dt by It is possible to have a situation in which d dt 0 c The average velocity of a particle is zero in a time interval It is possible that the instantaneous velocity is never zero in the interval but 0 d The average velocity of a particle moving on a straight line is zero in a time interval It is possible that the instantaneous velocity is never zero in the interval Infinite accelerations are not allowed

O Single Correct MCQ In a large building there are 15 bulbs of 40 W 5 bulbs of 100 W 5 fans of 80 W and 1 heater of 1 kW The voltage of the electric mains is 220 V The minimum capacity of the main fuse of the building is A B 12 A 14 A

Four particles each with a mass of M equidistant from each other move along a circle with a radius of R under the action of their mutual gravitational attraction The speed of each particle is A B 1 2 GM R 1 2 2 GM R 1 2 2

O Single Correct MCQ The pressure that has to be applied to the ends of a steel wire of length 10 cm to keep its length constant when its temperature is raised by 100 C is For steel Young s modulus is 2x 10 N m 2 and coefficient of thermal expansion is 1 1 x 10 5 C A B C 2 2 107 Pa 2 2 106 Pa 2 2 108 Pa

Phy Section A This section contains 20 SINGLE CORRECT TYPE questions Each question has 4 choices 1 2 3 and 4 out on The unit of self inductance is Volt meter Volt ampere Volt second volt second ampere

Resistance of AB wire is 2000 2 and resistance of voltmeter is 1500 2 If sliding contact is in the middle of AB wire then reading of voltmeter will be V 16volt 1 3 V 3 10 V 75007 B www A 2 6 V 4 8V 750 t 8 V

Board Competitive Exams 41 Two projectiles of same mass and with same velocity are thrown at an angle 60 and 30 with the horizontal then which will remain same 1 Time of flight 2 Range of projectile 3 Maximum height acquired 4 All of these 42 Two particles having mass M and m are moving in a circular path having radius R and r If their time periods are same then the ratio of their angular velocities will be 3 1 43 If A B A 181 and B will be 1 90 3 0 R 4 then angle between A 2 120 4 60 44 A particle moves along a circle of radius with constant tangential acceleration If the velocity of the particle is 80 m s at the end of the second revolution after motion has begun the tangential acceleration is 1 40 m s 2 640 m s 4 40 m s 3 160 m s 45 The vector sum of two forces is perpendicular to their vector differences In that case the forces 1 Are equal to each other 2 Are equal to each other in magnitude 3 Are not equal to each other in magnitude 4 Cannot be predicted 46 A wheel has angular acceleration of 3 0 rad s and an initial angular speed of 2 00 rad s In a time of 2 s it has rotated through an angle in radian of 1 10 2 12 3 4 m 47 A particle is moving such that its position coordinates x y are 2 m 3 m at time t 0 6 m 7 m at time t 2 s and 13 m 14 m at time t 5 s 1 2 SECTION D Assertion Reason Type Questions In the following questions a statement of assertion A is followed by a statement of reason R 3 Motion in a Plane 225 Average velocity vector V from t 0 to f 5 s is 1 13 147 3 2 1 1 5 1 If both Assertion Reason are true and the reason is the correct explanation of the assertion then mark 1 2 If both Assertion Reason are true but the reason is not the correct explanation of the assertion then mark 2 3 If Assertion is true statement but Reason is false then mark 3 4 If both Assertion and Reason are false statements then mark 4 A If ALB then A BI IA BI R If ALB then A B is perpendicular to A B A The addition of two vectors P and Q is commutative R By triangle law of vector addition we can prove P Q Q P A A vector cannot be divided by other vector R A vector can be divided by a scalar 4 A At the highest point the velocity of projectile is zero R At maximum height projectile comes to rest A Horizontal range of a projectile is always same for angle of projection with horizontal or 0 with vertical R Horizontal range depends only on angle of projection

correct If time taken by a pendulum to complete 20 vibrations is 60 60 s then time period of the pendulum in s up to appropriate significant figures is 03 03 s 3 0 s htains 20 SINGLE CORRECT TYPE questions Each question has 4 choices 1 2 3 and 4 out of which only one is O3 00 s 21 26 31

A particle is projected with an unknown velocity at and angle of 45 with an unknown velocity at an angle of 45 with horizontal It grazes the top of a pole at a distance of 4m from the point of projection and falls 6m behind the pole If the height of pole is 4n 10 in metre then the value of n is

Statement l For a binary solution of two known liquids A and B with the knowledge of density of solution molarity can be converted into molality Statement II Molarity changes with change in temperature O Statement I is correct but II is incorrect Statement II is correct but I is incorrect Both the statements are correct Both the statements are incorrect

long cylindrical conductor of cross sectional area S is made of a material whose resistivity depends only the distance r from the axis of the onductor as p where is a constant The resistance per unit length of such a conductor is N The value of N is S

com Two cylindrical conductors with equal Cross section and different conductivity and o are connected in series end to end If current I flows through his combination then O Current density J is different for both conductors O Electric field strength E is same in both conductors At junction of these conductors there will be no charge accumulation At junction of these conductors there will be some charge accumulation Th

34 An ideal gas is made to expand from an initial volume V to a final volume 4V through three different thermodynamic processes as shown in figure Process 1 is adiabatic 2 isothermal and 3 isobaric If AU AU and AU denote the change in internal energy of the gas in the three processes respectively then P4 1 AU AU AU3 AU 3 AU AU AU3 TI HT T V MCV wat X TV T C 4V 2 AU AU AU 4 AU3 AU AU

A 50 KW DC generator produces a potential difference 250 V If the resistance of the transmission line is 12 what percentage of the original power is lost during the transmission Answer

lons Each question has 4 choices 1 2 3 and 4 out of which only one is correct For the given potentiometer set up A is a primary cell which drives the setup J is null point for no deflection in the galvanometer Then choose the correct statement Rh Hwiw O R If R increases J will moved to the right For measuring r E should be always less than that of V If Rh increases J will shift towards right All are correct

R Maximum deviation of the projectile is 20 60 A Three vectors having magnitudes 10 10 and 25 cannot produce zero resultant R If three vectors are producing zero resultant then sum of magnitude of any two is more than or equal to magnitude of third and difference is less than or equal to the magnitude of third

gm of ice at 20 C is kept into a calorimeter containing 10 gm of water at 10 C The specific heat of water is twice that of ice When equilibrium is reached the calorimeter will contain 2 20 gm of ice 1 20 gm of water 4 5 gm ice and 15 gm water 3 10 gm ice and 10 gm of water 17 Water falls from a height 500 m What is the rise in temperature of water at bottom if in the water 1 0 06 0 3 3

ion A Section contains 20 SINGLE CORRECT TYPE questions Each question has 4 choices 1 2 3 and 4 out of which only one is correct a 6 respectively then the maximum percentage error in Pis c d A physical quantity Pis described as P 07 05 03 If maximum percentage error in measurement of a b c and dare 2 1 and 3

In the figure the potentiometer wire AB of length L has resistance 5r is joined to the cell D of emt E and internal resistance The cell C semfis resistance is 2r The galvanometer shows zero deflection when AJ 5 Then the value of a is P w lesi and its internal

For the circuit shown the power dissipated in the external variable resistance R is plotted against R The value of internal resistance of cell e is O r 360 O r 130 O r 4 O r 60 90

4 XERCISE 10 300 gm of water at 25 C is added to 100 gm of ice at 0 C The final temperature of the mixture is 5 C E 3 5 C 11 Two spheres made of same substanno 52 2 15 1 4 0 C 4

correct How many significant figures are there in the measured value 0 0005203 07 LE CORRECT TYPE questions Each question has 4 choices 1 2 3 and 4 out of which only one is 02

4 A hallow cylinder is rotating about its axis and a man is sticking against its wall Find minimum angular speed of cylinder so that he does not fall assuming s 0 5 and radius 2m a 3 2 rad s b 10 rad s d 3 2 rpm c 6 4 rad s

Paragraph A small object mass m falls freely from rest under gravity from a height h and strikes obliquely Fixed smooth inclined plane as shown in figure The impact is elastic 1 51 The time for which object remains in air between 1st and 2nd impact 2u cos a 2u g sin a 3 Fixed Fixed inclined plane 2u sin a g 2u g 52 The displacement of object along the inclined plane between 1st and 2nd impact will be 1 8h sin a 2 4h sin a 3 8h cosec 2 4 1 55 Loss in K E of bullet m 3M m u cos E 8M 1 3m M m u cos 3 8M 56 After impact the string 1 2M gl 2 mu 2M 7 3 mu V3 57 Using the condition 1 gl 3 3 gl gl

For a given cell the internal resistance is found to be proportional to the current drawn from it Then which of the following is the best representation of terminal potential difference V vs current drawn from the cell C K L O

is constructed by fixing small identical balls at the ends of a light rod of length I The dumbbell stands vertically in the corner formed by a frictionless wall and frictionless floor After the bottom end is slightly pushed towards the right the dumbbell begins to slide Value of which of the following quantities vanish when the upper ball is losing contact with the wall

A between them The wavelength of the standing wave is 2 2 42 4 3 63 Prato a farm 3 P2 time 1 21 A 3 6 05 3 6 05 A 65 A small body of mass 0 10kg is executing S H M of 05 0 10 kg fo amplitude 1 0 m and period 0 20 sec The maximum force 1 31 0m dare 0 20 sec F acting on it is 1 98 596 N 3 100 20 N 2 985 96 N 4 76 23 N 1 1 06 Two trains are moving towards each other at speeds of 20 m s and 15 m s relative to the ground The first train sounds a whistle of frequency 600 Hz The frequency of the whistle heard by a passenger in the second train before the train meets is the speed of sound in air is 340 m s 2 585 Hz 52 Sy x Frror Y 3751 1 P21A 2 1 2160 2 242 A 4 3 63 A 1 98 596 N 3 100 20 N 06 af 1 600 Hz 15 m s f atte fara to 340 m s 2 985 96 4 76 23 M 2 58

Vm is the maximum voltage between trends of the secondary terminal of a transformer used in a half wave rectifier When the PN junction diode is reverse biased what will be the potential difference between two ends of the diode A Zero B V m 2 C Vm

4 May be ve zero or ve potential If a unit positive charge is taken from one point 7 to another point over an equipotential surface then 1 Work is done on the charge by electric field 2 Work is done by the charge against the electric field 3 Work done is non zero constant by the field 4 No work is done by the field mly charged

Major product of the given reaction is CH T CH CH CH CH O CH CH HI Product CH CH OH and CH CH CH CH I I CH CH CH CH CH OH and CH CH I T CH CH CH CH OH and CH CH I I CH3 CH T CH CH C CH and CH CH OH

15 An imaginary graph is plotted betwee potential and distance then E electric fiel A B 1 At point A E ve 2 At point C E ve 3 At point C E ve 4 At point C E 0 tic force in h

Which of the following quantities depend on the choice of zero potential or zero potential energy 3 1 Potential at a point 2 Potential difference between two points 3 Change in potential energy 4 Potential energy of a system of two charges field of

What is the effect on the image formed by the convex lens if the central portion of the lens is wrapped in black paper as show in the figure Lens O No image is formed by remaining portion of lens O The central portion of image will be absent O There will be two images O Full image formed but will be less bright

180 A compound microscope has a magnification of 30 when final image is formed at 25 cm from the eye piece What is magnification produced by the objective if the focal length of eyepiece is 5 cm 05 0 072 10 0

A ventilated room has a temperature of 15 C What happened to the speed of sound if the temperature is doubled every 10 minutes Using the equation complete the table below and construct a graph to show the relationship between temperature and speed of sound Interpret the data and your conclusion EXPLORE Table 1 Speed of Sound and Temperature Room temperature every 10 minutes C 15 C 30 C 45 C 60 C 75 C Speed of Sound s w Speed of Sound m s Graph here Temperature every 10 minutes C

11 A pair of spur gears consists of a 24 teeth pinion rotating at 1000 rpm and transmitting power to a 48 teeth gear The module is 6 mm while the face width is 60 mm Both gears are made of steel with an ultimate tensile strength of 450 N mm They are heat treated to a surface hardness of 250 BHN Assume that velocity factor accounts for the dynamic load Calculate LO 6 7 i beam strength ii wear strength and iii the rated power that the gears can transmit if service factor and the factor of safety are 1 5 and 2 respectively

A person can see clearly upto a distance of 30 cm He wants to read a book placed at distance of 50 cm from his eyes What is power of lens required for spectacles O 2 0 D O 1 33 D O 1 0 D O 1 50 D

Aperture of human eye is 2 mm Assuming the mean wavelength of light be 5000 The angular limit of resolution of eye is nearly 0 1 minute 2 minute O 3 minute O 1 degree