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Physics Questions and Answers October 10, 2022

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Two vectors, one 3 N and the other 4 N, can have a resultant of (a) 0 N. (b) 5 N. (c) 8 N. (d) Any of these.

The average speed of a gazelle traveling a distance of 2 km in a time of one-half hour is (a) 1 km/h. (b) 2 km/h. (c) 4 km/h. (d) greater than 4 km/h.

Consider N noninteracting elections (NNA) in a box of sides Lx, Ly, Lz. Assume that the dispersion relation is E(K) CK4, where c is a constant, the ratio of the ground state energy per particle to the fermi energy is

If gravity between the Sun and Earth suddenly vanished, Earth would continue moving in (a) a curve. (b) a straight line. (c) an outward spiral. (d) an inward spiral.

Somebody who says Thats only a theory likely doesnt know that a scientific theory is (a) an educated guess. (b) a hypothesis. (c) a vast synthesis of well-tested hypotheses and facts. (d) None of these

The magnitude of the gravitational force on a satellite is constant if the orbit is (a) parabolic. (b) circular. (c) elliptical. (d) All of these.

The component of velocity that can remain constant for a tossed baseball is (a) horizontal. (b) vertical. (c) Either of these. (d) None of these.

A cavity contains black body radiation in eqm at temperature T. The specific heat per unit volume of the photon gas in the cavity is of the form CvrT3 where r is a constant. The cavity is expanded to twice its original volume then allowed to equilibrate at the same temperature T. The new internal energy per unit volume is

If the Sun were twice as massive, its pull on Mars would be (a) unchanged. (b) twice as much. (c) half as much. (d) four times as much.

The highest ocean tides occur when Earth and the Moon are (a) lined up with the Sun. (b) at right angles to the Sun. (c) at any angle to the Sun. (d) lined up during spring.

The rotational inertia of an object is greater when most of the mass is located (a) near the rotational axis. (b) away from the axis. (c) on the rotational axis. (d) off center.

When a tin can is whirled in a horizontal circle, the net force on the can acts (a) inward. (b) outward. (c) upward. (d) None of these.

A machine cannot multiply (a) forces. (b) distances. (c) energy. (d) None of these.

When 100 J are put into a device that puts out 40 J of useful work, the efficiency of the device is (a) 40%. (b) 50%. (c) 60%. (d) 140%.

Lift a 100-N crate with an ideal pulley system by pulling a rope downward with 25 N of force. For every 1-m length of rope pulled down, the crate rises (a) 25 cm. (b) 25 m. (c) 50 cm. (d) None of these.

When a model car speeds up to three times its original speed, its kinetic energy is (a) the same. (b) twice as great. (c) three times greater. (d) None of these.

The power required to raise a 100-kg crate a vertical distance of 2 m in a time of 4 s is (a) 200 W. (b) 500 W. (c) 800 W. (d) 2000 W.

The work done on a 100-kg crate that is hoisted 2 m in a time of 4 s is (a) 200 J. (b) 500 J. (c) 800 J. (d) 2000 J.

A big fish swims upon and swallows a small fish that is at rest. Right after lunch, the fattened big fish has a change in (a) speed. (b) momentum. (c) Both. (d) Neither.

The impulsemomentum relationship is a direct result of Newtons (a) first law. (b) second law. (c) third law. (d) law of gravity.

consider a system of two spins S1 S2 taking values 1 with internal energy JS1S2. when it is in thermal equilibrium at temp. T, for largest temperature, the average energy of the system varies as cKbt. with c given by

Consider the nuclear fission Ne 20 ?2He 4 + C 12 Given that the binding energy/ nucleon of Ne 20 , He 4 and C 12 are 8.03 MeV, 7.07 MeV and 7.86 MeV respectively. Identify the correct statement. (a) energy of 9.72 MeV has to be supplied (b) energy of 12.4 MeV will be supplied (c) 8.3 MeV energy will be released (d) energy of 3.6 MeV will be

According to Bohrs theory, the time-averaged magnetic field at the centre (i.e. nucleus) of a hydrogen atom due to the motion of electrons in the n th orbit is proportional to (n = principal quantum number) (a) n 2 (b) n 3 (c) n 4 (d) n 5

Two deuterons undergo nuclear fusion to form a Helium nucleus. Energy released in this process is (given binding energy per nucleon for deuteron = 1.1 MeV and for helium = 7.0 MeV) (a) 25.8 MeV (b) 32.4 MeV (c) 30.2 MeV (d) 23.6 MeV

As an electron makes a transition from an excited state to the ground state of a hydrogen-like atom/ion (a) kinetic energy decreases, potential energy increases but the total energy remains the same (b) kinetic energy and total energy decrease but potential energy increases (c) its kinetic energy increases but potential energy and total energy

Energy required for the electron excitation in Li ++ from the first to the third Bohr orbit is (a) 12.1 eV (b) 36.3 eV (c) 108.8 eV (d) 122.4 eV

If the binding energy per nucleon in 3 Li 7 and 2 He 4 nuclei are 5.60 MeV and 7.06 MeV respectively, then in the reaction p + 3 Li 7 ? 2 2 He 4 energy of proton must be (a) 39.2 MeV (b) 28.24 MeV (c) 17.28 MeV (d) 1.46 MeV

A nuclear transformation is denoted by X(n,?) 3 Li 7 . Which of the following is the nucleus of element X (a) 5 B 9 (b) 4 Be 11 (c) 6 C 12 (d) 5 B 10

Using a nuclear counter the count rate of emitted particles from a radioactive source is measured. At t = 0 it was 1600 counts per second and at t = 8 seconds it was 100 counts per second. The count rate observed, as counts per second, at t = 6 seconds is close to (a) 200 (b) 360 (c) 150 (d) 400

Find the voltage v, in the circuit in Figure 3. (NOTE there is a current controlled voltage source). 180 A 21 i 60 Figure 3 20 W 2ix

Evaluate the following circuits, where R 2002 and R 600 02 a. Voltage Divider Figure 4(a) find V, V, and show that Vs V V. b. Current Divider Figure 4(b) find I, I2, and show that Is 1 1. (a) (b) Vs 10 V R ww V V R Is 10 A Figure 4 R 1 R

Find Io using nodal analysis.

Find Vo using loop analysis. 12v www 12. ww ww ... 8V ,

Find Io using loop analysis.

Find Vo using loop analysis from the given circuit.

In Youngs double-slit experiment, slits are separated by 0.5 mm and the screen is placed 150 cm away. A beam of light consisting of two wavelengths, 650 nm and 520 nm, is used to obtain interference fringes on the screen. The least distance from the common central maximum to the point where the bright fringes due to both the wavelengths coincide

A single slit of width b is illuminated by coherent monochromatic light of wavelength ?. If the second and fourth minima in the diffraction pattern at a distance 1 m from the slit are at 3 cm and 6 cm, respectively from the central maximum, what is the width of the central maximum? (i.e. the distance between the first minimum on either side of the

Unpolarized light of intensity I 0 is incident on the surface of a block of glass at Brewsters angle. In that case, which one of the following statements is true? (a) Transmitted light is partially polarized with intensity I 0 /2 (b) Transmitted light is completely polarized with intensity less than I 0 /2 (c) The reflected light is completely

A spherical shell has inner radius a and outer radius b, as shown. It has uniform charge density r. Spherical Shell Inner radius a Outer radius b Uniform charge density p a. If the total charge of the shell is Q, write an expression for the charge density that depends on Q and the radii of the shell. b. How many regions do you need to find the

0.1 01 008 000 0.0 00 0 002 0 01 0.06 00 008 00 00 0 0 002 01 00 0.06 000 mA 4mB Momentum (kgms) 00 002 0 002 0.04 0.06 Momentum (kgms) A Cart A 10 Momentum (kgms) mA4mB Cart B 10 20 30 A Cart A mA4mB 10 A Cart B initial directions of motion 20 Cart A 20 Cart B 30 40 30 track has negligible friction Colliding blocks during the collision 50

Electron in hydrogen atom first jumps from third excited state to second excited state and then from second excited to the first excited state. The ratio of the wavelength , , emitted in the two cases is (a) 75 (c) 275 (b) 2720 (d) 207

Two boys are standing at the ends A and B of a ground where AB a. The boy at B starts running in a direction perpendicular to AB with velocity v. The boy at A starts running simultaneously with velocity v and catches the other boy in a time t, where t is (a) a v (b) a (v v.) (c) a(vv.) (d) a vv

An inductor 20 mH, a capacitor 50 F and a resistor 400 are connected in series across a source of emf V 10 sin 340 t. The power loss in A.C. circuit is (a) 0.51 W (c) 0.76 W (b) 0.67 W (d) 0.89 W

A plank with a box on it at one end is gradually raised about the other end. As the angle of inclination with the horizontal reaches 30 the box starts to slip and slides 4.0 m down the plank in 4.0s. The coefficients of static and kinetic friction between the box and the plank will be, respectively (a) 0.6 and 0.5 (c) 0.4 and 0.3 mg 07 (b) 0.5

Two radioactive substances A and B have decay constants 52 and respectively. At t0 they have the same number of nuclei. The ratio of number of nuclei of A to those of B will be (1e) after a time interval (a) 42 (b) 22 (c) 12(d) 142

The molecules of a given mass of a gas have r.m.s. velocity of 200 ms at 27C and 1.0 x 105 Nm pressure. When the temperature and pressure of the gas are respectively, 127C and 0.05 10 Nm, the r.m.s. velocity of its molecules in ms is (a) 1002 400 (b) 3 1002 (c) 3 100 (d) 3

When two displacements represented sin(oot) and y b cos(ot) are superimposed is (a) simple harmonic with amplitude (b) simple harmonic with amplitude a b (c) simple harmonic with amplitude (ab) 2 (d) not a simple harmonic by y a the motion

A shell of mass 200 gm is ejected from a gun of mass 4 kg by an explosion that generates 1.05 kJ of energy. The initial velocity of the shell is (a) 100 ms (c) 40 ms (b) 80 ms (d) 120 ms

A microscope is focussed on a mark on a piece of paper and then a slab of glass of thickness 3 cm and refractive index 1.5 is placed over the mark. How should the microscope be moved to get the mark in focus again (a) 4.5 cm downward (b) 1 cm downward. (d) 1 cm upward (c) 2 cm upward

A particle is executing a simple harmonic motion of amplitude a. Its potential energy is maximum when the displacement from the position of the maximum kinetic energy is (a) 0 (c) (b) ta (d) a2

Youngs double-slit experiment with slit separation 0.1 mm, one observes a bright fringe at angle 1/40 rad by using the light of wavelength ? 1 . When the light of wavelength ? 2 is used a bright fringe is seen at the same angle in the same setup. Given that 1 and 2 are in the visible range (380 nm to 740 nm), their values are (a) 400 nm, 500 nm

Calculate the limit of resolution of a telescope objective having a diameter of 200 cm, if it has to detect light of wavelength 500 nm coming from a star. (a) 610 10 9 radian (b) 152.5 10 9 radian (c) 457.5 10 9 radian (d) 305 10 9 radian

A graph is a picture of ordered pairs of numbers. Thus, to draw a graph we must use graph paper and a set of ordered pairs of numbers. Graph paper is provided at the end of this experiment. You must cal culate or determine experimentally the ordered pairs of numbers. In this experiment, calculate the or dered pairs using the mathematical equation
A graph is a picture of ordered pairs of numbers. Thus, to draw a graph we must use graph paper and a set of7. Plot each ordered pair of numbers as a single point (d, C), (d2, C), etc. 8. Plot each point clearly usingPROCEDURE 2 The relationship between the area of a circle and the radius of the circle can be stated as

Use Leontiefs inputoutput table for the six sectors of the economy of the United States for 1958 to find the production schedule (total outputs) required to fulfill each of the final demands below. Sector FN FM E S Final demand A 100,000 100,000 100,000 100,000 100,000 100,000 Final demand B 300,000 200,000 400,000 100,000 100,000 900,000 Final

Assuming the sun to have a spherical outer surface of radius r, radiating like a black body at temperature tC, the power received by a unit surface, (normal to the incident rays) at a distance R from the centre of the sun is r(t273)4 (a) 4R 16r ot (b) R ro(t273) (c) (d) R where o is the Stefans constant. R 4rt

A parallel plate air capacitor of capacitance C is connected to a cell of emf V and then disconnected from it. A dielectric slab of dielectric constant K, which can just fill the air gap of the capacitor, is now inserted in it. Which of the following is incorrect (a) The energy stored in the capacitor decreases K times. (b) The chance in energy

(a) Derive using Newtons laws a secondorder differential equation for h(t), assuming that the only two forces acting on the cork are gravity and buoyancy. Gravity pulls the cork downward with a force equal to the mass of the cork times the gravitational constant g. Buoyancy is an upwards force felt by the cork due to water pressure, and is equal

A block A of mass m, rests on a horizontal table. A light string connected to it passes over a frictionless pulley at the edge of table and from its other end another block B of mass m, is suspended. The coefficient of kinetic friction between the block and the table is When the block A is sliding on the table, the tension in the string is (a)

A wire of a certain material is stretched slowly by ten per cent. Its new resistance and specific resistance become respectively (a) 1.2 times, 1.3 times (c) both remain the same (b) 1.21 times, same (d) 1.1 times, 1.1 times

Two similar springs P and Q have spring constants K, and K, such that K, K. They are stretched, first by the same amount (case a,) then by the same force (case b). The work done by the springs W, and Wo are related as, in case (a) and case (b), respectively (a) W Wi P (b) WWW W Q

The phasecontrolled 6pulse (3phase) rectifier, shown in Fig. PI.I, is supplied from a 460V, 60Hz power line, whose inductance, L,, is seen from the input terminals of the controlled rectifier. The rectifier operates with a firing angle, a 30 producing an average current, Io. of 140 A. Neglect resistances of the supply circuit. (a) Determine the

A thermodynamic process is shown in the figure. The pressures and volumes corresponding to some points in the figure are P P 3 10 Pa A 3 V 2 10m A P 8 10 Pa B V 5 x 10 m. D B In process AB, 600 J of heat is added to the system and in process BC, 200 J of heat is added to the system. The change in internal energy of the system in process AC

The switch in the circuit seen in Figure has been in position a for a long time before moving instant neously to position bat 0. a) Construct the sdomain equivalent circuit for t 0. b) Find V1 and v1. c) Find V2 and v2. 50 kn m 450 V 16F2 10F 31.25 ml 125 12

Two bodies of masses m and 4 m are moving with equal K.E. The ratio of their linear momenta is (a) 41 (c) 12 (b) 11 (d) 14

Choose the only false statement from the following (a) In conductors, the valence and conduction bands may overlap (b) Substances with energy gap of the order of 10 eV are insulators (c) The resistivity of a semiconductor increases with increase in temperature (d) The conductivity of a semiconductor increases with increase in temperature

Apply mesh current analysis to the circuit shown in Figure 4 to find the RIV matrix for this circuit.

An explosion blows a rock into three parts. Two parts go off at right angles to each other. These two are, 1 kg first part moving with a velocity of 12 ms and 2 kg second part moving with a velocity of 8 ms. If the third part flies off with a velocity of 4 ms, its mass would be (a) 7 kg (c) 3 kg (b) 17 kg (d) 5 kg

A polyatomic gas with n degrees of freedom has a mean energy per molecule given by nkT N nkT (b) 2N nkT 2 3kT (d) 2

The magnifying power of a telescope is 9. When it is adjusted for parallel rays the distance between the objective and eyepiece is 20 cm. The focal length of lenses are (a) 10 cm, 10 cm (c) 18 cm, 2 cm (b) 15 cm, 5 cm (d) 11 cm, 9 cm

In a diffraction pattern due to a single slit of width a, the first minimum is observed at an angle 30 when light of wavelength 5000 is incident on the slit. The first secondary maximum is observed at an angle of (a) sin1 (b) sin1 (c) sin (1) (d) sin1

In the study of transistor as amplifier, if and 1, where, I, I, and I are the collector, B E IE IB base and emitter currents, then 2000 (a) (b) B (c) B (d) B (1x) (1) (1x) (1x)

A wheel having moment of inertia 2 kgm about its vertical axis, rotates at the rate of 60 rpm about this axis. The torque which can stop the wheels rotation in one minute would be TT (a) Nm 18 2TT. (b) Nm 15 TT Nm 12 TT (d) Nm 15

The wavelength associated with an electron, accelerated through a potential difference of 100 V, is of the order of (a) 1000 (c) 10.5 (b) 100 (d) 1.2

Consider two mercury barometers, one having a cross-sectional area of 1 cm 2 and the other 2 cm 2 . The height of mercury in the narrower tube is (a) half. (b) twice. (c) the same. (d) None of these.

A rock suspended by a weighing scale weighs 5 N out of water and 3 N when submerged in water. What is the buoyant force on the rock? (a) 3 N (b) 5 N (c) 8 N (d) None of these.

A ball rolls without slipping. The radius of gyration of the ball about an axis passing through its centre of mass is K. If radius of the ball be R, then the fraction of total energy associated with its rotational energy will be R (a) KR KR2 (b) R K R (c) (d) K KR

A completely submerged object always displaces its own (a) weight of fluid. (b) volume of fluid. (c) density of fluid. (d) All of these.

The pressure at the bottom of a pond does NOT depend on the (a) acceleration due to gravity. (b) water density. (c) depth of the pond. (d) surface area of the pond.

Pumice is a volcanic rock that floats in water. The density of pumice compared with that of water is (a) less. (b) equal. (c) greater. (d) none because it sinks

When you scale up an object to 3 times its linear size, the surface area increases by (a) 3 and the volume by 9. (b) 3 and the volume by 27. (c) 9 and the volume by 27. (d) 4 and the volume by 8.

A particle moving along xaxis has acceleration f, at time t, given by f fo (1), where f, and T are constants. The particle at t 0 has zero velocity. In the time interval between t 0 and the instant when f 0, the particles velocity (v.) is (a) fT (c) fT (b) fT (d) ft.

When you bend the branch of a tree by hanging on its end, the top side of the branch is under (a) tension. (b) compression. (c) Both. (d) Neither

According to Hookes law, if you hang by a tree branch and note how much it bends, then hanging with twice the weight produces (a) half the bend. (b) the same bend if the branch doesnt break. (c) twice the bend. (d) 4 times the bend.

If the volume of an object were to double, with no change in mass, its density would (a) halve. (b) double. (c) be the same. (d) None of these.

The crystals that make up minerals are composed of (a) atoms with a definite geometrical arrangement. (b) molecules that perpetually move. (c) X-ray patterns. (d) 3-dimensional chessboards.

A uniform rope of length L and mass m, hangs vertically from a rigid support. A block of mass m, is attached to the free end of the rope. A transverse pulse of wavelength, is produced at the lower end of the rope. The wavelength of the pulse when it reaches the top of the rope is the ratio ,is (a) (b) (c) (d) m mm m m m m

How many electrons are there in the third shell of sodium, Na (atomic number 11)? (a) None (b) One (c) Two (d) Three

Assuming the radius of the earth as R, the change in gravitational potential energy of a body of mass m, when it is taken from the earths surface to a height 3R above its surface, is (a) 3 mg R 3 (b) mgR (c) 1 mg R 3 (d) mgR

A long solenoid has 500 turns. When a current of 2 ampere is passed through it, the resulting magnetic flux linked with each turn of the solenoid is 4 x10 Wb. The self inductance of the solenoid is (a) 2.5 henry (c) 1.0 henry (b) 2.0 henry (d) 40 henry

The density of water at 20C is 998 kgm and at 40C 992 kgm. The coefficient of volume expansion of water is (a) 10 C (c) 2 10C (b) 3 10 C (d) 6 10 C

A black body at 1227C emits radiations with maximum intensity at a wavelength of 5000. If the temperature of the body is increased by 1000C, the maximum intensity will be observed at (a) 5000 (c) 3000 (b) 6000 (d) 4000

Hot sand cools off faster at night than does vegetation. Compared with vegetation, sands specific heat capacity is (a) lower. (b) higher. (c) about the same. (d) Cant say.

The amount of heat transferred to a system can be measured in (a) calories. (b) joules. (c) Either. (d) Neither

Which of these temperatures is likely when a container of water at 20C is mixed with water at 28C? (a) 19C (b) 22C (c) 30C (d) Higher than 30C

When wind speeds up as it blows over the top of a hill, atmospheric pressure there (a) increases. (b) decreases. (c) isnt affected. (d) reduces to zero.

An electron of a stationary hydrogen atom passes from the fifth energy level to the ground level. The velocity that the atom acquired as a result of photon emission will be 24hR (a) 25m 25hR (b) 24m 25m (c) 24hR 24m (d) 25hR (m is the mass of the electron, R, Rydberg constant and h Plancks constant)

On a new scale of temperature (which is linear) and called the W scale, the freezing and boiling points of water are 39 W and 239 W respectively. What will be the temperature on the new scale, corresponding to a temperature of 39 C on the Celsius scale (a) 78 W (b) 117 W (d) 139 W (c) 200 W

The flight of a blimp best illustrates (a) Archimedes principle. (b) Pascals principle. (c) Bernoullis principle. (d) Boyles law.

Which of the following circular rods (given radius r and length 1), each made of the same material and whose ends are maintained at the same temperature will conduct most heat (a) r r 11, 0 (c) rr 121, (b) r 2r 1 1 (d) r 2r 1 21

In a hydraulic press operation, the output piston cannot (a) move farther than the input piston. (b) exceed the force input. (c) exceed the input pistons speed. (d) produce increased energy.