Basic Physics Questions and Answers

A structural steel rod has a radius of 10mm and length of 1 0m A 100 kN force stretches it along its length Young s modulus of structural steel is 2 10 Nm2 The percentage strain is about A 0 16 C 0 08 B 0 32 D 0 24

What is the initial acceleration in meters per second squared of a charge of 16 microcoulombs that has a mass of 15 milligrams as it is released 9 5 centimeters to the right of charge q1 on the x axis if q1 is 3 3 nanocqulombs and a charge q2 of 5 4 nanocoulombs is placed at a position of 5 8 centimeters to the right of q1 along the x axis Round your answer to the nearest whole number Do NOT show the units in your answer Remember Your answer could be negative In other words g1 3 3 nanocoulombs x1 9 5 centimeters q2 5 4 nancoulombs x2 5 8 centimeters 91 x2 x1

A truck starts from rest and has acceleration of 4 m s2 A box is inside truck which is at 6 m from 2 open end of truck The coefficient of friction between box and truck is 0 1 How much time box will take to slip out of truck 1 2 s 3 3 8 s 2 3 1 s 4 15 s

An insect is moving uniformly at speed 2 cm s on outer surface of a vertical right circular cone Without changing its sense of motion about axis of cone it completes a round trip and reaches to starting point A in minimum time Given Apex angle of cone 60 Height of cone 3 cm A

Select True statements regarding DIAC You can select multiple correct options DIAC has symmetrical breakdown characteristics and its leads are interchangeable In conduction mode it act as a open switch and its acts like a high resistance with large voltage drop across it In conduction mode it acts like a low resistance with about 3 V drop across it Its turn on voltage is about 0 7v and it has asymmetrical breakdown characteristics

AGTO has the following disadvantages as compared to a conventional thyristor GTO has faster switching speed Magnitude of latching and holding currents is more in a GTO On state voltage drop and the associated loss is more in a GTO Gate drive circuit losses are less

Two stars each of mass M and separated by a distance d orbit about their center of mass A planetoid of mass m m M moves along the axis of this system perpendicular to the orbital plane Let Tp be the period of simple harmonic motion for the planetoid for small displacements from the centre of mass along the z axis axis perpendicular to plane of orbit and let T be the period of motion for two stars Determine the ratio Ts Tp to the nearest integer

Given a plot of equipotential lines how would yo draw the electric field lines a Perpendicular towards lower potential b Parallel to all equipotential lines c Perpendicular towards higher potential d Perpendicular towards higher energy

i ii sodium atom Na sodium ion sodium chloride NaCl Na chlorine atom 10 ionic bond choride ion Sodium has a atomic number 11 a Explain why sodium atoms have no overall charge b When sodium reacts with chlorine ions are formed Explain why i Giant structures are usually very hard Explain why ii A ring has a mass of 5g and occupies a volume of 0 34cm 3 Pure gold has a density of 19 3g cm3 Is the ring made of pure gold Why do giant covalent structures have higher melting points than

A heater has a resistance of 10 ohms draws a 12 A current from an supply What is the power of the heater and wh hermal energy is supplied by the heater in 10 seconds O 14 4W 1 44 x 10 4 1440W 1 44 x 10 4 J 14 4 kW no energy transfer 144W 144 x 10 41

a AB b BC Q13 A battery of emf 10V and internal resistance 30 is connected to a resistor The current in the circuit is 0 5A The terminal voltage of the battery when the circuit is closed is a 10 V b 0 V c 1 5 V d 8 5V Q14 When three identical bulbs of 60 W 200 V rating are connected in series to a 200 V supply the power drawn by them will be a 20 W b 60 W 180 0 1 Q15 A long solenoid carrying a current produces a magnetic field B along its axis If the current is doubled and the number of turns per cm is halved the new value of the magnetic field is b 2B d B 2 a B c 4B B c CD Q16 The value of angle of dip at a place where vertical component and horizontal component of earth s magnetic are equal a 60 b 45 a proportional to 2 180 0 c zero only if 0 180 c 180 W Q17 If the beams of electrons and protons move parallel to each other in the same direction then they a Attract each other b repel each other c no relation d neither attract nor repel Q18 A battery is connected between two points A and B on the circumference of a uniform conducting ring of radius r and resistance R One of the arcs AB of the ring subtends an angle 8 at the centre The value of magnetic field at the centre due to current in the ring is b NAB c 30 Q19 What is the angle of dip at the magnetic poles a 30 b 30 Q21 The role of inductance is equivalent to a Inertia b force d DE Q24 The Unit of electric dipole moment is a Newton c Coulomb d 10 W c 45 d 90 b inversely proportional to r d zero for all value of 0 Q20 The magnetic flux linked with a coil of N turns of area of cross section A held with its plane parallel to the field B is a NAB 2 C NAB 4 c energy Q22 Identify the wrong statement a Eddy currents are produced in a steady magnetic field b Eddy currents can be minimized by using laminated core c Induction furnace uses eddy current to produce heat d Eddy current can be used to produce braking force in moving trains c Farad d None of these d Zero Q23 In series LCR circuit the phase angle between the supply voltage and current is a Tan XL XC R b Tan R XL XC c Tan R XL XC d momentum d Tan XL Xc R d Debye Q25 Point out the correct statement s about the validity of Kirchhoff s junction rule a It is based on law of conservation of charge b outgoing currents add up and are equal to incoming currents at a junction c bending or reorienting the wire does not change the validity of Kirchhoff s junction rule d all of these SECTION B This section consists of 24 multiple choice questions with overall choice to attempt any 20 questions In case more than desirable number of questions is attempted ONLY first 20 will be considered for evaluation Q26 The no of turns in the primary coil of a transformer is 200 and the no of turns in the secondary is 10 If 240 V a c is applied to primary the output from the secondary a 6 V b 12 V c 24 V d 48 V Q27 Figure shows the electric field lines of a positive point charge The work done by the field in moving a small positive charge from Q to P is

The net magnetostatic flux out of any closed surface is 0 O True O False For a gravitational force to exist a minimum of two point masses must exist True False True 5 points The magnitude of electrostatic field in a region of space is represented by 5 points the length of an electrostatic field line in that region False 5 points

The resistance capacitive reactance and in ductive reactance of series LCR circuit are 6 00 1200 and 400 respectively a Calculate total impedance of the circuit b Calculate phase angle between peak volt onl rront the piroui

What happens when two bodies are rubbed against each other A They acquire equal and similar charges B They acquire equal and opposite charges C They acquire different charges but in different amounts depending upon masses D They do not acquire any charge

Your are on an unknown planet You send a signal to your friend on Earth He tells you that he will be coming in a spacesphip with a speed of 0 995c according to where you are It will take approximately 35 min in his time How long will you wait if he is taking a straight path

Identify the type of instruction for the given example XTHL CO2 O Arithmetic instruction O Data transfer instruction O Branch control instruction

Four identical point masses each of mass m and carrying charge q are placed at the corners of a square of sides a on a frictionless plain surface If the particles are released simultaneously the kinetic energy of the system when they are infinitely far apart is B A 2 2 1 a 2 2 2 C 2 2 4 D 2 2 1 a a a F face BRI SEPE CAC TAC DU FIE forf 4 A 2 2 1 B 2 2 a C 2 4 a a D 4 2 1 a

density 3 28 At standard temperature and pressure the a gas is 1 3 kgm and the speed of sound in gas is 330 ms Then the degree of freedom of the g BCECE Mains 2012 will be a 5 c 7 b 6 d 8

143 Escherichia coli cells were grown for many generations in 15NH4Cl as sole nitrogen source Subsequently these cells were grown exactly for four generations in medium containing 14NH4CI The DNA from these cells were isolated and separeted If 15N 15N represents the two strands of DNA where both strands have heavy nitrogen 15N 14N as intermediate DNA and 14N 14N as DNA containing light nitrogen the ratios for heavy intermediate light DNA respectively would be a 1 0 7 Relative amounts n b 1 1 6 c 0 1 7 d 0 8 0

i Name the following process A A process that involves cells in living organisms taking in oxygen and producing carbon dioxide B A process that takes in carbon dioxide and produce oxygen ii Explain why increasing average temperature can lead to flooding happening more often iii Describe two effects of climate change that will most affect cities near coastlines i Suggest two ways in which people in cities can prepare for these

A long wire carrying alternating current i i cost is kept along the axis of a toroid The inner and outer radii of the toroid are R and R2 respectively The toroidal loop has rectangular cross section with N turns and height h If R 4R io 3 amp N 1000 and h 2 mm Then the maximum emf induced in the loop is A 3 x 10 7 In 2 volt B C D 6 x 10 7 In 2 volt 12 x 10 7 In 2 volt 24 x 10 7 In2 volt rough R 2 R Di fro BE

Initialization of 8255 in 8085 based traffic light controller is required for CO 3 O Turn OFF the traffic lights O Turn ON the traffic lights O O Assign port A ans Port B as a output port Assign required ports as a input or output port

Three point charges 9 92 and 93 are taken such that when 9 and 9 are placed close together to form a single point charge the force on q at distance L from this combination is a repulsion of 2 unit in magnitude when 92 and q3 are combined the force on q at distance L is an attractive force of magnitude 4 units Also 93 and 9 when combined exert an attractive force on 9 of 92 magnitude 18 unit at same distance L The algebraic ratio of charges q 92 and q3 is A 1 2 3 B 2 3 4 D 4 3 2 C 4 3 1

A beam of mass 350 kg and length L 6 m is attached to a wall and suspended by a light cord of length L 10 m If the cord can only withstand tension under 2500 N how far along the length of the beam can a box of mass m 50kg be placed before it snaps 0 27 m 11 1 m 3 49 m 777 Li The mass can be placed anywhere on the beam

A force F x i y j N where x and y coordinates are in metres acts upon a body and it moves along the path ABCDA as shown The work done by the force is 0 2 D A 0 0 20 J 020 J 42 J 3 2 B 3 0 X

TO 180 Mark for Review The refracting angle of a prism is A and refractive index of the material of the prism is cot A 2 The angle of minimum deviation is 180 2A O 180 3A 180 2A 90 02 5 hr m

A car travels 250 miles in the same time a truck travels 225 miles If the speed of the car is 8 mph faster than the speed of the truck find the speed of each vehicle Recall mph miles per hour You must clearly show your variable designation s equation and algebraic solution to receive full credit

20 m s on hitting the bat The force of the ball lasts for 0 01 s Find the average force exerted the ball by the bat 22 State any three characteristics of vector product Find the magnitude of 81 81 8k

Calculate the position vector ID from A to D and find the magnitude of AD 0 6 m 0 4 m D 0 6 m 1 8i 0 3j mand 1 825m 1 8i 0 3j mand1 825 m B 1 2 m 0 7 m X b 1 8i 0 3j m and 1 825 m d 1 4i 1 1j mand 1 78m

Air at a temperature of 18 C passes through a heat exchanger at a velocity of 32 m s where its temperature is raised to 800 C It then enters a turbine with the same velocity of 32 m s and expands until the temperature falls to 620 C On leaving the turbine the air is taken at a velocity of 60 m s to a nozzle where it expands until the temperature has fallen to 500 C If the air flow rate is 2 25 kg s calculate a the rate of heat transfer to the air in the heat exchanger b the power output from the turbine assuming no heat loss and c the velocity at exit from the nozzle assuming no heat loss

B Calculate the conductivity of intrinsic Ge at room temperature of 300 k When donor type impurity is added to the extent of 1 impurity atom in 107 Ge atoms calculate the resistivity Also calculate the resistivity when an acceptor impurity of 1 atom in 107 Ge atoms is added At room temperature the values are n 2 5 x 10 3 cm Un 3800 cm V s Hp 1800 cm V s No of Ge atoms 4 4 x 1022 cm

Elements X and Y of 3rd period form binary compounds with fluorine P and Q respectively Some information is given below Compound P Non polar and has only 6 bond angles of 90 each Compound Q Non polar and has only 12 bond angles of 90 each The number of lone pairs present in each molecule of compounds P and Q are a and b respectively The value of a b is

A bead slides without friction in a wire that is rotating with an angular velocity w in the force free space Write down th Lagrange s equation of motion and show that the radial velocity and acceleration are given as dr dt C 2 r w r g sin wt C constant ants and

BLOCK P OF WEIGHT 50 N IS KEPT ON A PLANE AND NOW PULLED SO THAT THE EXTENSION IN THE SPRING IS 10 CM THE STIFFNESS OF THE SPRING IS 4 N CM AND THE COEFFICIENT OF FRICTION BETWEEN THE BLOCK AND THE PLANE IS M 0 3 FIND 1 THE VELOCITY OF THE BLOCK AS THE SPRING RETURNS TO ITS UNDEFORMED STATE AND II THE MAXIMUM COMPRESSION IN THE SPRING

1 The great limestones caverns were formed by dripping water TDI varto a If water droplets of 10 ml fall from a height of 5 m at a rate of 10 per minute what is the average force exerted on the limestone floor by the droplets of water b Compare this force to the weight of a water droplet The density of water is 1000 kg m

4 The voltage across a parallel plate capacitor with area A and separation d varies with time t as V at where a is a constant a Find the displacement current between the plates b If the direction of the displacement current is what is the magnetic field magnitude and direction outside the capacitor in the xy plane at a distance r from its center c What is the magnitude of the induced electric field at this same point 54 nlana alastamaanatic wave of fearmanex 140 GHz mavae in the nacitiva avie nswer

Q5 A telescope of aperture 3 cm is focused on a window at 80 cm distance fitted with a wire mesh of opening 2 cm Will the telescope be able to observe the wire mesh The wavelength of the light used is

In a new system of units the fundamental quantities mass length and time are replaced by acceleration a density p and frequency f The dimensional formula for force in this system is 4 b pa f 6 d p a4f a pa c p af 6

1 point The sum of two point charges is 11 C When they are 3 3 cm apart each experiences a force of 175 N Find the magnitude of a repulsive List your two answers in increasing order of magnitude C C a attractive List your two answers in increasing order of magnitude C C charges given that the forc

ons a R The figure shows electrons passing through a resistor The arrow shows the direction in which the electrons are moving Which of the following statements is incorrect b The motion of electrons from point a to point b constitutes a current O The potential at a is higher than the electric potential at b O The electrons are losing electric potential energy as they move through the resistor from a to b O The electrons flow due to the potential difference O The electric potential is higher at point b than at point a

A uniform thin rod AB 12 m long weighing 24 kg is supported at end B by a flexible light string and a lead weight of very small size of 12 kg is attached at end A The rod floats in a river with one half of its length submerged For this situation mark out the correct statement s Take g 10 m s density of water 1000 kg m A The tension in the string is 360 N B The tension in the string is 40 N C The volume of the rod is 60000 m D The point of application of the buoyancy force is passing through C centre of mass of the rod

2 The two arms of a U tube have areas of cross section 1 cm and 1 m and it contains water A force of 1000 dynes is applied on the arm of larger area To keep the water in equilibrium the force to be applied on the other arm is A 100 N B 0 1 N C 0 1 dyne

An aluminum rod elastic modulus of 70 GPa yield strength of 40 MPa as shown in Fig a with circular cross section is subjected to an axial load of 10 kN Given the stress strain curve for a tensile test of this material is shown in Fig b determine 1 The approximate elongation increase in length of the rod when under the tensile load of 10 kN 2 If the specimen is unloaded the applied force being removed and then reloaded with 10 kN find the new total elongation as compared to the original before question 1 length YA AB d MPa BRERARS 50 40mile 40 30 20 10 600 mm 15 mm 400 mm 10 045 10 KN elastic in AB 10 11 0 001 Bc Opc plastic AB 0 01 AB 31 3 May 56 6 Mpsey p 56 6 31 4 0 0005 70x10 EBC from graph EBC 0 045 under load 0 mm EAE 400mm E

The value of acceleration due to gravity go on the surface of a planet with radius double that of earth and same mean density as that of the earth is ge acceleration due to gravity on the surface of earth A 9p 29e B 9p ge 2 C Tp ge 4

A liquid is kept in a cylindrical vessel When the vessel is rotated about its axis the liquid rises at its sides If the radius of the vessel is 0 05 m and the speed of rotation is 2 revolutions per second the difference in the heights in cm of the liquid at the centre and at the sides of the vessel is take g 10 ms 2 and 10

A ray of light is incident normally on one of the faces of prism of apex angle 30 and refractive index 2 The angle of deviation of the ray in degree is 10 15 20

A transformer consists of magnetic circuit in which it employs windings Keeping all factors which affect the performance of transformer give the answers of following questions below 1 How many types of transformer are there 2 Explain the losses in a transformer and how can these remove 3 What is the rating of transformer Give the reason 4 When efficiency of transformer will be maximum

Which of the following order of acidic strength for alcohol is correct OH H OH HO HO HOMO OOH MOH OH OH min sec

A vessel containing a liquid is accelerated horizontally If the free surface of the liquid makes an angle of 30 with the horizonal the acceleration of the vessel is in m s A 4 9 3 B 9 8 3 c 9 8 3

A boat with some stones in it is floating in a pond If some stones are dropped in water and they sink in water the level of water in the pond will A Increases B Decreases C Remains the same