Physics Questions

3 Focal length of magnifiying lens is 5 cm What will be the maximum magnification possible 1 4 3 6 2 5 4 7

A material B has twice the specific resistance of A A circular wire made of B has twice the diameter of a wire made of A then for the two wires to have the same resistance the ratic B A of their respective lengths must be B A a 1 c 4 b 1 1 1 2 d 2

into the shape of an inverted U such that the horizontal part has a length 1 15 cm The bent ends of the wire are partially immersed in two pools of mercury with 2 5 cm of each end below the mercury s surface The entire structure is in a region containing a uniform 0 0065 T magnetic field directed into the page An electrical connection from the mercury pools is made through the ends of the wires The mercury pools are connected to a 1 5 V battery and a switch S When switch S is closed the wire jumps 35 cm into the air measured from its initial position Based on the facts provided answer the following questions 0 The speed A 5 2 ms C 70 cms Mercury S 15 V Mercury of the wire as it leaves the mercury is B 2 5 ms D 7 cms

20 A block B is suspended from a cable that is attached to the block at E wraps around three pulleys and is tied to the back of a truck D If the truck starts from rest when XD is zero and moves forward with a constant acceleration of ap 3 2 m s if the speed of the block at the instant xD 3m is A m s B 4m m s B XD D C m s D 1 m s

second sphere due to the first Check that the ratio ke G mm is dimensionless Look u of Physical Constants and determine the value of this ra does the ratio signify

Three objects A a solid sphere B a thin circular disk and C a circular ring each have the same mass M and radius R They all spin with the same angular speed o about their own symmetry axes The amounts of work W required to bring them to rest would satisfy the relation 1 WC WB WA 3 WB WA WC 2 WA WB Wc 4 WA WC WB

A motorboat is racing towards north at 36 km h w r t water and the speed of water current in that region is 10 km h towards east The resultant speed of the boat is nearly 1 37 m s 3 46 km h 2 37 km h 4 26 km h

4 When object is at a distance of 30 cm from concave mirror Consider two reflection first one on plane mirror second one on concave mirror The velocity of final image after two reflection is a 9 m s Find a 10 m s V 10 m s f 20 cm O 20 m s 50 cm

A Young s double slit experiment uses a monochromati source The shape of the interference fringes formed on screen is a circle c parabola b hyperbola d straight line

The resultant of two vectors of magnitudes 3A and 2A is R If the first vector is doubled then the magnitude of resultant is also doubled The angle between two vectors is 1 60 3 90 2 120 4 180

0 A uniformly charged solid sphere of radius R has potential Vo measured with respect to o on its surface For this sphere the equipotential surfaces with potentials 3V0 5V 3Vo 24 4 and have radius R R R3 and R4 respectively Then Vo 4 a R 0 and R R4 R3 b 2R R

Four bodies A B C and D are projected from the ground with same speed at angles 39 43 52 and 46 with the horizontal respectively The correct relation for their horizontal range are 1 RD RB RA RC 2 RA R R Ro 3 RD RB RA Rc 4 R D

When 5V potential difference is applied across a wire of length 0 1 m the drift speed of electrons is 2 5 10 4 ms If the electron density in the wire is 8 1028 m 3 the resistivity of the material is close to a 1 6 10 6 m c 1 6 10 8 Om b 1 6 10 5 m 16x10 70m

5 The function sin t represents a a periodic but not simple harmonic motion with a peria TC 0 b a periodic but not simple harmonic motion with a peria 2 c a simple harmonic motion with a period d a simple harmonic motion with a period 3 2

Find out the acceleration of the block B in the following systems B 4 a 2m b B 3m

The time taken by a photoelectron to come out after the photon strikes is approximately a 104s c 10 16 g b d 10 10 s 10 1e

A 20 cm long capillary tube is dipped in water The water rises up to 8 cm If the entire arrangement is put in a freely falling elevator the length of water column in the capillary tube will be a 10 cm b 8 cm c 20 cm d 4 cm

Two bodies performing have same amplitude and frequency Their phases at a certain instant are as shown in the figure The phase difference between them is x A 10 0 5 A A x

2 Two block of masses m and m are connected with the help of a spring of spring constant k initially the spring in its natural length as shown A sharp impulse is given to mass m so that it acquires a velocity Vo towards fight If the system is kept on smooth floor then find a the velocity of the centre of mass b the maximum elongation that the spring will suffer k m m M Vo

Example 30 1 Two plane mirrors M and M are inclined at angle 0 as shown A ray of light 1 which is parallel to M strikes M and after two reflections the ray 2 becomes parallel to M Find the angle 0 2 M N 0 A Fig 30 23 Solution Different angles are as shown in Fig 30 24 In triangle ABC B 0 a an ala eee 1 777 M a 90 0 A 60 C Fig 30 24 0 0 0 180

Example 2 The figure shows a cross sectional view of a masonry dam whose length perpendicular to the diagram in 30 m The depth of water behind the dam is 10 m The masonry of which the dam is constructed has a density of 3000 kg m a Find the dimensions x and 2x if the weight of the dam is to be 10 times the horizontal force exerted on it by water Check the stability of the dam with respect to its overturning about the edge through point O b 10 m Water X dam 2x

17 An elevator is moving upward with an acceleration a It has velocity v at t 0 A man inside the elevator lifts a body of mass m slowly through a height h in interval t 0 to t to The average power developed by the man in elevator reference frame in interval t 0 to t to is A C m g a h to mgh to 1 B m g a v ato 2 D mg v 12 ato

An object is placed 21 cm infront of a concave mirror of radius of curvature 20 cm A glass slab of thickness 3 cm and refractive index 1 5 is placed closed to the mirror in space between the object and the mirror Find the position of final image formed if distance of nearer surface of the slab from the mirror is 10 cm 3cm 0 10 cm 21cm

1 A charged particle of mass m and charge q is released from rest from position x 0 0 in a uniform electric field Eoj The angular momentum of the particle about origin a is zero c increases with time b is constant d decreases with time

10 A 2 25 mm Dipole moment Electric flux The number of circular divisions on the shown screw gauge is 50 It moves 0 5 mm on main scale for one complete rotation and main scale has 1 2 mm marks The diameter of the ball is B 2 20 mm C 1 20 mm lectric field 25 D 1 25 mm

When a mass is rotating in a plane about a fixed point its angular momentum is directed along 1 the radius 85 2 the tangent to the orbit 3 a line perpendicular to the plane of rotation 4 the line making an angle of 45 to the plane of rotation

Figure shows an irregular shaped with AB moving with velocity v as shown Find the emf induced in the wire OB B

2 A nuclear transformation is denoted by X n a Li Which of the following is the nucleus of element X a Be 10 d B inquit onerating from 50 Hz mains b 2C6 c Be

A man of mass m climbs on a rope of length L suspended below a balloon of mass M The balloon is stationary with respect to ground If the man begins to climb up the rope at a speed Vrel relative to rope In what direction and with what speed relative to ground will the balloon move A downwards B upwards C downwards mvrel m M mvrel M MV rel m M D downwards M m V rel M direction At the highest

35 A gaseous mixture consists of 16 g of helium and 16 g of oxygen The ratio mp a 1 62 of the mixture is Cv b 1 59 c 1 54 d 1 4

6 The moment of the force F 41 51 6k at 2 0 3 about the point 2 2 2 is given by 1 81 41 7k 2 41 1 8k 3 71 81 4k 4 71 41 8k

5 How many electrons may be removed from a body so that it may have a charge of a 1 milli coulomb b 1 micro coulomb h 6 25 x 1012 electrons

A thermocouple is made from two metals Antimony and Bismuth If one junction of the couple is kept hot and the other is kept cold then an electric current will a flow from Antimony to Bismuth at the hot junction b flow from Bismuth to Antimony at the cold junction c now flow through the thermocouple d flow from Antimony to Bismuth at the cold junction

A 10 kg solid sphere of radius r 0 8 m is rolling without slipping on a horizontal rough surface with 8 m s The force applied by the right half of the sphere on the left half is 30x Newton Find the value of x 8 m s

A whistle producing sound waves of frequencies 9500 HZ and above is approaching a stationary person with speed v ms The velocity of sound in air is 300 ms If the person can hear frequencies upto a maximum of 10 000 HZ the maximum value of v upto which he can hear whistle is a 15 2 ms c 15 ms 1 15 2 b PHIGONV 1 ms d 30 ms 1

Starting with a sample of pure 66 Cu c 7 minutes 8 Zn in 15 minutes The corresponding half life is a 15 minutes b 10 minutes of it decays into d 5 minutes

We are given the following atomic masses 238 238 05079 u16 234Th 234 04363 u 2013 4He 4 00260 u gitvilos brit boow The energy released during the alpha decay of 238 U is 1 6 00 MeV 3 3 75 MeV 2 4 25 MeV 4 5 03 MeV

1 A cell a resistor a key and ammeter are arranged as shown in the circuit diagrams of Figure12 1 The current recorded in the ammeter will be R A R R www ii Fig 12 1 a maximum in i b maximum in ii c maximum in iii d the same in all the cases CK A A K iii

The period of oscillation of a simple pendulum of length L suspended from the roof of a vehicle which XL then find X moves without friction down on inclined plane of inclination a 60 is given by g I I T Scr 2000 1 35

In a region steady and uniform electric and magnetic fields are present These two fields are parallel to each other A charged particle is released from rest in this region The path of the particle will be a a helix c ellipse straight line b d circle

An observer looks at a distant tree of height 10 m with a telescope of magnifying power of 20 To the observer the tree appears JEE Mains 2016 1 20 times nearer 3 10 times nearer 2 10 times taller 4 20 times taller int for determination of refractive index of glass of a prism by i 8 plot it was found d that it emerges at angle 79 In that case

10 The angular magnification of telescope is 30 If all the light which passes through objective lens of diameter 80 cm also passes through eye piece lens then find out diameter of eye piece lens 1 cm cm 3 2 8 cm 3 013 8 cm 4 0 cm

Example 1 2 If 10 electrons move out of a body to another body every second how much time is required to get a total charge of 1 C on the other body 3 Therefore 01 C t C

A light rope fixed at one end of a wooden clamp on the ground passes over a tree branch and hangs on the other side figure 5 W9 It makes an angle of 30 with the ground A man weighing 60 kg wants to climb up the rope The wooden clamp can come out of the ground if

Section F Collision 1 A particle moving with kinetic energy K makes a head on elastic collision with an identical particl rest Find the maximum elastic potential energy of the system during collision

3 A microscope is focussed on a mark on of paper and then a slab of glass of thickness cm and refractive index 1 5 is placed over the mark How should the microscope be moved to get the y mark in focus again nward

A mercury thermometer is placed in a gravity free hall without touching anything As temperature rises mercury expands and ascend in thermometer If height ascend by mercury in thermometer is h then by what height centre of mass of mercury and thermometer system descend

In the given string pulley arrangement all the pulleys and strings are massless and smooth The acceleration of block will be ZUL 901 1 g 4 3 g 2 D Halle GE m 2 4 g GOBROL 2 g 8 from C

Focal length of converging combination of two ler is 20 cm The ratio of dispersive power is 2 One of the focal length will be 1 6 cm 2 10 cm 3 15 cm 4 20 cm

material and having the same cross section have Three rods made of the same as A been joined as shown in the figure Each rod is of the same length The left and right ends are kept at 0 C and 90 C respectively The temperature of junction of the three rods will be JEE 2001 a 45 C c 30 Cabeldo Solution Let 0 be the temperature of the junction say B Thermal resistance of all the three rods is equal Rate of heat flow through AB Rate of heat flow through CB Rate of heat flow through BD Solving this equation we get The correct option is b Here R Thermal resistance f heat flow b 60 C d 20 C H 0 C Temperature difference TD Thermal resistance R Fig 22 14 stomex3 sowo wif 90 8 90 0 0 0 D B R R R 0 C 0 0 60 C A BSS elama itssh AS schpen Fig 22 15 1 s 90 C 90 C 90 C 90 C