Basic Physics Questions and Answers

Monochromatic green light of wavelength 5 x 10 7 m illuminates a pair of slits 1 mm apart The separation between consecutive bright fringes on the interference pattern formed on a screen 2 m away is 0 0 25 mm O 0 1 mm O 1 0 mm O 0 01 mm

Q No 13 A B DD A Find out value of Y 1 2 3 4 Correct Answer 1 Your Answer 3 A B A B A B D Y

There exists a uniform magnetic field perpendicular to the plane of the figure in a cylindrical region of radius a the magnetic field is increasing at a constant rate of aTs 1 A particle having charge q is at a point P outside the field region The particle is slowly moved to infinity Calculate work done by the external agent in moving the particle to infinity along tangential direction PQ 2 1 3 qra a 4 q a a 6 qra a 3 4 0

Two coherent monochromatic point sources S and S of wavelength 600 nm are placed symmetrically on either side of the centre of the circle as sown The sources are separated by distance d 1 8 mm This arrangement produces interferences fringes visible as alternate bright and dark spots on the circumference of the circle The angular separation between two consecutive bright spots is 40 Which of the following options is are correct 2017 A dark sport will be formed at the point P At P the order of the fringe will be maximum The total number of fringes produced between P and P in the first quadrant is close to 3000 The angular separation between two consecutive bright spots decreases as we move from P to A B C D S ld 40 S

Which one of the following bonds produces a solid that reflects light in the visible region and whose electrical conductivity decreases with temperature and has high melting point 1 covalent bonding 2 metallic bonding 3 van der Waal s bonding

7 A square loop of side 5 cm enters a magnetic field with 1 cms The front edge enters the magnetic field at t 0 then which graph best depicts emf 1 2 3 104 TR eer on 3 0 5 3 10 V 5cm 0 5 20 X X 20 25 X X 20 25 X X 20cm X X X X t s 25 t s X X X X t s x B 0 6T X

A particle having charge q and mass m is projected with velocity 2 3 in unifor electric field E Ej change in momentum of particle during a time interval At is O qEoAt qE At 2 qEoAt Zero

A hollow metallic cube has edge length 12 cm A liquid whose coefficient of volume expansion is 6 x 10 10 C 1 is poured into it upto height 3cm When temperature increases height of liquid in cube remains unchanged Coefficient of linear expansion of cube s material is n 10 10 C 1 find n Question Type Numerical Type

13 A silicon p n junction diode has the following parameters N 2 10 8 cm x N 2 10 6 cm T tp 2 x 10 6 s D 25 cm s and Dp 8 cm Tn Tp s A light source is incident only on the depletion region producing a generation current density of Jgen 50 mA cm 2 The diode is open circuited The generation current density forward biases the junction inducing a forward bias current in the opposite direction to the generation current A steady state condition is reached when the gen eration current density and forward bias current density are equal in magnitude What is the induced forward bias voltage at this steady state condition

y x515x y x as shown in the figure 20 ded by the curve and line 20 iii Find the volume solid obtained by rotating the region bounded by the curves y x 1 y 5 x realme

A screening test for cancer has a low false positive rate and a low false negative rate in that with careful use one finds the disease in 95 of the patients having it and only 5 of the patients not having it Assume that 4 of a certain population has the disease What is a the probability that a person who reacts positively to the test will in fact have the disease

View In English A ball after falling from a height of 10 m strikes the roof of a lift which is descending down with a velocity of 1 m s The recoil velocity of the ball will 1 8 m s 11 m s 12 m s 15 m s 2 3 4 Correct Answer 3 Status unattempted

17 A mass of 5 kg is suspended by a string 10 m long A horizontal force is applied on the mass to pull it 5 m from a vertical line through the point of suspension Find the magnitude of the force Ans 28 29 N

Centripetal force 1 can change speed of the body 3 is constant for uniform circular motion 2 is always perpendicular to direction of motion 4 all of these

Match the columns I and II Column 1 A Angle B Power C Work D Energy Length 4 MLT 2 a A 3 B 4 C 1 D 3 b A 2 B 1 C 5 D 4 c A 3 B 1 C 4 D 2 d A 2 B 1 C 3 D 4 OA OB Column II 1 ML T 3 2 MOLOTO 3 MLT 2 O C O D

1 The condition for obtaining secondary maximum in the diffraction pattern due to single slit is a is width of the slit n is order of maxima is wavelength of incident light 1 a sin 0 n2 2 a sin 0 2n 1 3 a sin 0 2n 1 4 a sin 0 n 2

A body of mass m placed on an inclined plane of inclination 30 with the horizontal as shown Then the acceleration of the block is g 30 m smooth fixed g 3 3g 4 g

The space between two large plane surfaces is 2 5 cm and it is filled with glycerine What force is required to drag a very thin plate 1m in area between the surfaces at a spee of 1 m s The plate is at a distance of 1 cm from one of the surfaces n 0 75Ns m ONO 100 N 75 N 50N

and B are placed in front of slits A and B respectively If pAtA BtB then the centra maxima may ONO not shift shift towards A if t tB

The energy of a tungsten atom with a vacancy in L small is 11 3KaV Wavelength of K photon for tungsten is 21 3pm If a potential difference of 62kV is applied across the X raystube following characterstic X rays will be produced ONO K L series only ko and L series only L series none of these

A conducting wire is bend into a loop as shown in the figure The segment AOB is parabolic given by t equation y 2x while segment BA is a straight line x 2 The magnetic field in the region B 8k tesia and the current in wire is 2A B x in m

Note The effective mass of the solid whose energy expression k A B cos k b cos k b near 0 0 is equal to Answer b d Bb 2 Bb Bb You are attempting question 5 out of 12 Bb A B OC OD

15 A body of density p is dropped from rest from a height h into a lake of density a where a p Neglecting all dissipative forces the maximum depth to which the body sinks before returning to float on surface e 3 h o p hp 2 hp ho

How long can an electric lamp of 500 W be kept glowing b fusion of 2 kg of deuterium Take the fusion reaction as 2He n 3 27 MeV 2 TH 1H 3 3 15 x 10 1 s 3 15 x 10 4 s min sec 3 15 x 107 s

Two blocks A and B having mass 4 kg and 8 kg respectively are connected by a string If a force of 120N is applied on 8 kg mass The tension between A and B is A 1 20 N T B 120N 2 40 N 3 50 N 4 60 N

A plank of mass M carrying a man of mass m moving horizontally with velocity u on frictionles horizontal surface If the man starts walkir towards right with velocity vo w r t the plank the velocity of centre of mass of plank man is Mu M m 3 u Vo 1 2 Mvo m M 4 u

The incident ray reflected ray and the outward drawn normal are denoted by the unit vectors a b and respectively Then choose the correct relation for these vectors mathange mothongo mathongo 1 6 2a 2 6 4 2 ak mathongo mathongo 7 mathongo mathongo mathonga mathong mathong

1 A rectangular rigid fixed block has a long horizontal edge A solid homogenous cylinder of radius R is placed horizontally at rest with its length parallel to the edge such that the axis of cylinder and edge of block are in the same vertical plane There is sufficient friction present at the edge so that a very small displacement causes the cylinder to roll off the edge with out slipping If the ratio of translational to rotational kinetic energies of the cylinder when its centre of mass is in horizontal line with the edge is N find N R 157

D Rewrite the following sentences using tenses mentioned in the brackets 1 I have to complete the work on time simple past simple future FEER WEEK n Thre I had to complete 2 The fruitseller will bring fresh fruits simple present simple past 3 Our colony has round the clock security arrangements simple past simple future 4 Ruchika has a new pair of jeans simple past simple future 5 The old woman lived alone simple present simple future That man is a musician simple past simple future

Two wires of same material whose lengths in the ratio 1 2 and area of crossection the ratio 2 1 respectively are connected parallel across a potential difference The ratio of their drift velocity is a 1 1 b 4 1 c 2 1 d None of these

ged par voi towards a circular region of uniform magnetic field B perpendicular and into the plane of paper as shown in the figure C is the centre of the circular region If the angle between the line CA and the x axis is 37 and the particle passes through point C then the radius of the circular region R is 1 3 q m mvo qB 6mv V X X X X X A X X X x x 37 x X X 2 4 X 4mvo 5qB 2mvo 2aR X

7 Four identical balls of mass m each are shown The three balls that lie on the ground are prevented from moving by applying horizontal forces not shown The reaction force between the fourth ball placed above and any of the other three ball is 1 3 mg 3 mg 6 8 2 2mg 3 4 mg

3 A long cylindrical wire of radius a carries a current I distributed uniformly over its cross section If the magnetic field at distances r a and R a from the axis have equal magnitude then 2 a Rr R r 2 1 a 3 a Rr R r 4 a R r

A radioactive substance named sam decays at a rate of proportional to its size It has a half life of 13 years If there are initially 19 grams of sam how long it will take in years untill there is only 1gram left

Rewrite the following sentences in negative and interrogative forms 1 Meena is washing clothes 5 The migratory birds are flying off 2 Rohan is playing a football match O Father is relaxing in the study OO OT ON MetaRing to her friend She is 6 The elephant is eating only leaves and grass now 7 The helper is cleaning the house 8 My neighbours are celebrating Christmas with friends this year

We have a galavanometer of resistance 252 It is shunted by a 2 50 wire The part of total current that flows through the galvanometer is given as A I 2 I 11 B I Io 1 C I 4 D I I 3 11 I 11 2 E I

In double slit experiment if one slit is blocked 35 then what we get on screen 1 Uniform brightness on screen 2 Diffraction pattern on screen 3 Interference pattern remain same 4 Intensity becomes half of Initial intensity

44 unacThree black bodies 1 2 3 have radius r r r3 Emissive powers of black bodies at temperature T are E E E3 Then correct relation between them is CALE Ex E E3 C E E E B E E E3 D E E E P do J CGA74

Two charged particles having charges luC and 1 C and of mass 50 g each are held at rest while their separation is 2m Now the charges are released Find the speed of the particles when their separation is 1m 3 1 ms 1 5 3 ms 10 1 3 1 2 ms NIN 1 4 ms

Four conducting plates of same area are placed close to each other Plate 1 2 and 3 are given charges Q 2Q and Q respectively while plate 4 is earthed with the help of switch S which was kept open initially Now if switch S is closed then amount of charge flown from earth to plate 4 is equal to

A block of mass M is connected to a spring of mass m and oscillates in simple harmonic motion on a horizon tal frictionless track The force constant of the spring is k and the equilibrium length is Assume that all portions of the spring oscillate in phase and that the velocity of a segment dx is proportional to the dis tance x from the fixed end that is vx x l v Also note that the mass of a segment of the spring is dm m l dx Find a the kinetic energy of the system when the block has a speed v and b the period of oscillation dx

The magnetic field at point P in the hollow cylindrical wire carrying a current i shown in the figure at a distance r from axis a r b is given by Taking current density to be uniform across its cross section 1 Moi r a 2 b a r a 12140 H 2 Moir 2 b a

Four identical charges Q are fixed at the four corners of a square of side a The electric field at a point P located symmetrically at a distance a 2 from the cente of the square is 1 Q 2 2 80a 2 Q reva 3 2 20 Re0a 4 20 09

Board Competitive Exams 23 A wire of natural length Young s modulus Y and area of cross section A is extended by x Then the energy stored in the wires is given by 1 3 1 YA 21 1 YI 2 A 2 1 YA 31 1 YA 21

When the light source is kept 20 cm away from a photo cell the stopping potential is 0 6 V If the source is kept 40 cm away then the stopping potential will be 0 3 V 0 6 V O 1 2 V

A particle is thrown at an angle a sin in air as shown in the figure The angle received from the inside wate is water A 15 Only one correct answer B 45 C 30 F D 60 43

3 Given a uniform disc of mass M and radius R A small disc of radius R 2is cut from this disc in such a way that the distance between the centres of the two discs is R 2 Find the moment of inertia of the remaining disc about a diameter of the original disc perpendicular to the line connecting the centres of the two discs 1 3 32 MR 2 5 16 MR2 3 11 64 MR 4 None of these

The deformation beyond elastic limit is called plasticity A Strain is a dimensionless quantity R Strain is internal force per unit area of a body

rd Competitive Exams Mechanical Properties of Fluids 133 A cylinder of radius R full of liquid of density p is rotated about its axis at en rad s The increase in pressure at the centre of the cylinder will be Day R 2 R 2 pu R 2 2 30

Light of wavelength 5890 4 falls on a double slit arrangement having separati d 0 2mm A thin lens of focal length f 1m is placed near the slits The linear separation of fringes on a screen placed in the focal plane of the lens is 1 3 mm 4 1 mm 2 4 mm 3 2 mm