Basic Physics Questions and Answers

1 AI A H T B x FIGURE 3 20 Two cells of emf s and in the series 7 7 are their ternal resistances For connections across A and C the combinatio can be considered as one cell of emf and an internal resistance r eq 1 E2 H T E eq E 12 and r F 1 12 eq C VACE IT eq Ir G2 12 Comparing the last two equations we get heline DUAL CAMERA Consider first two cells in series Fig 3 20 where one terminal of by Sourcadeo is joined together leaving the other terminal in either cell Physics Eeq A I If we wish to replace the combination by a single cell between A and C of emf and internal resistance r we would have eq eq Teq 3 63 3 64 3 65 In Fig 3 20 we had connected the negative electrode of the first to the positive electrode of the second If instead we connect the two negatives Eq 3 61 would change to VBC E2 Ir and we will get 2 CO

In an LCR circuit the resonating frequency is 500 kHz If the value of L is doubled and value o C is decreased to 1 times of its initial values ther 8 1 the new resonating frequency in kHz will be 1 250 2 500 3 1000 4 2000

27 When a resistance of 20 22 connected in parallel with a galvanometer then its deflection reduces from 50 divisions to 10 divisions the resistance of galvanometer is 1 80 Q 3 40 Q 2 100 S 4 50 Q

A conducting sphere of radius R is given a charge Q The electric potential and the electric field at the centre of the sphere are respectively Q 47 R G 1 Zero and Q 2 47 R EO and Zero Q 4t Eo R 4 Both are zero 3 and Q 4 Eo R EO

Low concentration of oxygen in the blood and tissues of people living at high altitude is due to a low temperature b low atmospheric pressure c high atmospheric pressure d both low temperature and high atmospheric pressure

A resistor of resistance R an inductor of inductance L and a capacitor of capacitance C are connected in series and the combination is connected to a battery of emf as shown At t 0 the switch S is closed Let after a very long time the thermal energy developed in circuit be Q energy stored in circuit be U and energy supplied by the battery be E Then A Q U E 1 1 2 B Q U E 1 3 4 DO UE 1 2 3 1 R 00

9 Block A of mass 2kg was pressed against a vertical wall with block B of mass 1kg as shown Coefficient of static friction between all the surfaces in contact is 0 5 Then total frictional force on A if it is prevented from sliding is A A 29 4 N C 19 6 N B B 49 N 9 8 N

1 Position x of a particle moving on a straight line as a function of time t is x 2t 12t 5 m The particle will come to rest at time t equal to 1 2 s 2 1 s 3 4 s 4 3 s

5 If a conductor has a potential V 0 and there are no charges anywhere else outside then a there must be charges on the surface or inside itself b there cannot be any charge in the body of the conductor c there must be charges only on the surface d both a and b are correct

ws cone of mass 200 gm suspended by a vertical jet of water from a garden hose The flow rate is 0 2 kg sec The water rises 8m if unimpeded Find the height of the cone top surface h in m at which water strike Assume the water emerges horizontally from holes at the top of cone YOUR ANSWER CORRECT ANSWER IS h 8

If the internal energy of ny moles of He at 10 T temperature is equal to the internal energy of n2 moles of H at 6 T temperature The ratio of n1 n is 03 5 02 01 05 3 Marks 4

In a transistor the base is very lightly doped as compared to the emitter because by doing so 1 The flow across the base region is mainly because of electrons 2 The flow across the base region is mainly because of holes 3 Recombination is decreased in the base region 4 Base current is high

13 A body of mass 1 kg is thrown upwards with a velocity ms It momentarily comes to rest after attaining a heigh 18 m How much energy is lost due to air friction g ms 2 1 20 J 2 30 J 3 40 J

A body initially at rest and sliding along a frictionless track from a height h as shown in the figure just completes a vertical circle of diameter AB D The heighth is equal to h 1 D 2 D BE A

A car travels in a straight line with average velocity of 80 km h for 2 5 h and then with average velocity of 40 km h for 1 5 h What is the average velocity for the total journey Corp Reg Office CG Tower A 46 52 IPIA Near City Mall Jhalawar Road Kota Raj 324005

nd e ne 17 A body of 10 kg is subjected to a force as shown in the figure The block moves along a straight line under the influence of this force The change in kinetic energy when the body moves from x 0 to x 4 m will be 1 15J 2 12 5 J 3 17 5J 102 1 F N I 10 5 2 3 4 x m

Two identical coaxial coils P and Q carrying equal amount of current in the same direction are brought nearer The current in 00 both P and Q decreases P increases while in Q decreases both P and Q increases Q increases while in P decreases

Q 23 A stone thrown at an angle 0 to the horizontal a projectile makes an angle 4 with the horizontal then its initial velocity and angle of projection are respectively d a 2h sin 8 b 2 2h sin 8 g c 2 2h g 2h

A block of mass 10 kg moving in the x direction with a constant speed of 10 ms is subjected to a retarding force F 0 1x J m during its travel from x 20m to 30m Its final KE will be a 475 J b 450 J c 275 J d 250 J

m s 350 wall 153 Two wires of copper having the length in the ratio 4 1 and their radii ratio as 1 4 are stretched by the same force The ratio of longitudinal strain in the two will be 1 1 16 2 16 1 3 1 64

13 A steady current flows in a metallic conductor of non uniform cross section Which of these quantities is constant along the conductor O a current O b current density O c electric field d drift speed

28 The centripetal force on a particle moving along mu circular path is given by F The mass m r velocity v and radius r of circular path of an object are 0 5 kg 10 m s and 0 4 m respectively If m u and r are measured with an accuracies of 0 01 kg 0 01 m s and 0 01 m respectively then what is the percentage error

Q1 Fill ups 2x 10 20 a The bread dough rises because Of the production of b Cholera is caused by c Like synthetic fibres plastic is also a d Rayon is also known as e To move a loaded trolley we have to f The atmospheric pressure as we move towards higher altit g Static friction is always than sliding friction h Friction in solid depends on the of surface I Compete with crops for nutrients J Harvested grains are to reduce moisture content

7 The voltage across a lamp is 6 0 0 1 volt and the current passing through it is 4 0 0 2 ampere Find the power consumed with error limits Hint Power Voltage x Current P V 1 Ans 24 saratt

0 Suppose the gravitational force varies inversely as the nth power of distance then the time period of a planet in circular orbit of radius R around the sun will be proportional to 1 R 2 R 1 3 R NCERT XI 1 194

A straight wire of infinite length having current starting point at O as shown in figure The magnetic field at point P will be up to 1 2 3 4 i Mo 4 r Mo i 4 r r 1 sine inward Mo i 4 r 1 cos 0 inward 1 sin0 outward Mo 1 cose outward Ar P

Q2 True false 2x 10 20 a Metal oxides are basic in nature b Graphite is a non metal which can conduct electricity c Yeast is used in the production of alcohol d Female anopheles mosquito is the carrier of malaria causing protozoans e Teflon is used to make non stick cookwear f Thermoplastic can easily be remoulded on heating g Lubricants increase friction between two surface h Friction causes wear and tear 1 The effect of a force may change by changing the direction of the applied force J Crop which are grown during the rainy season are known as kharif crop

Contact Number 966759193078527521718 10 A ball is thrown vertically downwards from a height of 20m with an initial velocity vo It collides with the ground loses 50 of its energy in collision and rebounds to the same height The initial velocity v is Take g 10 ms 2 1 14 ms 1 2 20ms 3 28ms

surrounding surfaces back into the medium The phenomenon occurs if the angle of incidence is greater than a certain limiting angle called 6 A concave lens of refractive index 1 5 is immersed in a medium of refractive index 1 65 What is the nature of the lens 7 An air bubble is formed inside water Does it act as a converging lens or a diverging lens

1 A steel wire can withstand a load up to 2940 N A load 150 kg is suspended from a rigid support The maximu angle through which the wire can be displaced from th mean position so that the wire does not break when th load passes through the position of equilibrium is 200 E 1 30 2 60 3 80

11 In a potentiometer of 10 wires the balance point is obtained on the 7th wire To shift the balance point to 9th wire we should a decrease resistance in the main circuit b increase resistance in the main circuit O c decrease resistance in series with the cell whose emf is to be measured d increase resistance in series with the cell whose emf is to be determined 1 po

The average e m f induced in a coil when current changes from 0 to 2 A in 0 5 seconds is 0 8 V The self inductance of the coil is 1 0 1 H 2 0 2 H 3 0 4 H 4 0 8 H

Masses of three copper wires are in the ratio 1 3 5 Their lengths are in the ratio 5 3 1 When they are connected in series to an external source the amounts of heats produced in them are in the ratio 1 125 15 1 3 5 3 1 2 4 1 15 125 1 3 5

Two charged particles having the same mass m and charges q and q separated by a distance d enter a uniform magnetic field B directed perpendicular to the paper inward with speeds v and v as shown The particles will not collide if neglect electrostatic force between charges x OV X x 1 d m v Bq X X X 2m 3 d m v X X X X V 2 d V V 2m qB 2m 4 d v V Ba

For which of the following dependences of drift velocity vd on electrical field E is ohm s law obeyed 1 Point vd is directly proportional to E vd is directly proportional to E2 vd is directly proportional to E

es towards the lens with a non uniform acceleration 8 Which of the following statement is true a Electrostatic force is a conservative force b Potential at a point is the work done per unit charge in bringing a charge from any poin c Electrostatic force is non conservative d Potential is the product of charge and work

The height h x of an object is given by the function h x 16x 25x 80 where x is time in seconds and is height in feet Find the instantaneous velocity at x 2 seconds Round to two decimal places if necessary

3 Consider a uniform electric field in the z direction The potential is a constant O a for any x for a given z b for any y for a given z c on the x y plane for a given z d all of these

25 A force of 2500 5 N is applied over an area of 0 32 0 02 m Calculate the pressure exerted over the area Ans 7812 5 503 9 N m

5 During an isothermal expansion a confined ideal gas does 150 J of work against its surroundings This implies that a 150 J of heat has been removed from the gas b 300 J of heat has been added to the gas c no heat is transferred because the process is isothermal 150 J of heat has been added to the gas

In a uniform electric field an electron of mass Me initially at rest moves through a certain distance in in time t1 A proton of mass Mp also initially at rest takes time t2 to move through an equal distance in the same uniform electric field Neglecting the effect of gravity the ratio t1 t2 is nearly equal to 1 Point Me O MP Me 2

An air bubble is formed inside water Does it act as a converging lens or a diverging lens An object approaches a convergent lens from the left of the lens with a uniform speed 5 m s and stops at the focus The image a Moves away from the lens with a uniform speed 5 m s b Moves away from the lens with a uniform acceleration c Moves away from the lens with a non uniform acceleration d Moves towards the lens with a non uniform acceleration

Two small spheres having equal positive charge Q coulomb on each exert force F on each other if placed at distance d are suspended by two insulating strings of equal length L from a hook fixed in a stand The whole setup is taken in a satellite into space where there is no gravity state of weightlessness Calculate angle between the strings and tension in each of the strings 1 Point

If a body starts its motion along the smooth track from P as shown in the figure then its velocity at the instant of leaving R is 1 5 m s 2 15 m s 3 10 m s 4 20 m s 10 m R 5m

3 31 Two particles with same mass are performing simple harmonic motions along x axis whose displacement x versus time t graphs are shown The ratio of their maximum kinetic energies is K K x m D 2A 1 1 1 3 1 4 2A 2 1 2 4 1 16 t s NCERT Test Series for NEET 2021 38 At the mean position of a particle undergoing SHM 1 Acceleration is maximum 2 Speed is maximum 3 Acceleration is minimum 4 Both 2 and 3

A charge Q is placed at the centre of a circle of radius R the work done in moving a charge Q from A to B so as to complete a semicircle is zero State the reason why 1 Point A B

The electric potential V is given as a function of distance x metre by following equation The value of electric field at x 1 is 1 Point V 5x 10x 9 V 20 Vm 1 6Vm 1 1 O 11 Vm

1 2 002 mm 3 1 998 mm Two rods of different materials having Young s modulus Y and Y and coefficient of thermal expansion a and a are fixed between two rigid supports The rods are heated to the same temperature if there is no bending of the rods the thermal stress developed in these rods are equal provided Y 02 1 Y 2 3 Y 0 Y 02 188 Y 0

Three masses m 2m and 3m are thrown from the top of a tower such that m is thrown vertically upward with 10m s 2m is thrown horizontally with 15m s and 3m is thrown vertically downward with 5m s The acceleration of centre of mass of the three body system will be 1 2 2g 2 g 3 2g 4 Zero

A coil and a bulb are connected in series with a 12 volt direct current source A soft iron core is now inserted in the coil Then 1 The intensity of the bulb remains the same 2 The intensity of the bulb decreases 3 The intensity of the bulb increases 4 Nothing can be said