Physics Questions and Answers October 02, 2022

(10M) a) What is a thin film Deduce the conditions of maxima and minima in case of a thin parallel film. (4M) b) Light of wavelength 5893 is reflected is nearly normal incidence from a soap film of refractive index 1.42. What is the least thickness of the film that will appear i) Black and ii) Bright

a) Define resolving power of a grating. Obtain an expression for resolving power of (10M) plane transmission grating. b) Calculate the minimum number of lines in a grating which will just resolve the lines of wavelengths 589nm and 589.6nm in the second order. (4M)

a) Explain the working of Michelson interferometer and describe how refractive (10M) index of a material is determined. b) When a thin film of a transparent material of 1.45 and 2 5890 is inserted in one of the arms of a Michelsons interferometer, a shift of 65 circular fringes is observed. Calculate the thickness of the film. (4M)

A sample of unknown compound gas X is shown by analysis to contain Sulphur and Oxygen. The Gas requires 28.3 seconds to diffuse through a small aperture into a vacuum. An identical number of oxygen molecules pass through the same aperture in 20seconds. Determine the molecular mass of gas X (O= 16, S= 32)

A horizontal force F is applied at the centre of mass of a cylindrical object of mass m and radius R, perpendicular to its axis as shown in the figure. The coefficient of friction between the object and the ground is u. The center of mass of the object has an acceleration a. The acceleration due to gravity is g. Given that the object rolls without

A wide slab consisting of two media of refractive indices n and n is placed in air as shown in the figure. A ray of light is incident from medium n to n at an angle 0, where sin 0 is slightly larger than 1n. Take refractive index of air as 1. Which of the following statement(s) is(are) correct air 1 n (A) The light ray enters air if n n (B) The

A particle of mass M 0.2 kg is initially at rest in the xyplane at a point (x l, y h), where l 10 m 10 ms along the and h 1 m. The particle is accelerated at time t 0 with a constant acceleration a positive xdirection. Its angular momentum and torque with respect to the origin, in SI units, are represented by I and respectively. i,j and k

Which of the following statement(s) is(are) correct about the spectrum of hydrogen atom (A) The ratio of the longest wavelength to the shortest wavelength in Balmer series is 95 (B) There is an overlap between the wavelength ranges of Balmer and Paschen series 1 (C) The wavelength of Lyman series are given by 1 20, where 20 20, where is the

1 cm R 4 cm Co (A) Maximum current through R is 1.2 x 106 ampere (B) Maximum current through R is 3.8 10 ampere (C) Maximum charge on capacitor Co is 8.4 x 102 coulomb (D) Maximum charge on capacitor Co is 2.4 x 102 coulomb,A long straight wire carries a current, I 2 ampere. A semicircular conducting rod is placed beside it on two conducting

A cylindrical tube, with its base as shown in the figure, is filled with water. It is moving down with a constant acceleration a along a fixed inclined plane with angle 0 45. P and P are pressures at points 1 and 2, respectively located at the base of the tube. Let (PP) (pgd), where p is density of water, d is the inner diameter of the tube and

An alphaparticle (mass 4 amu) and a singly charged sulfur ion (mass 32 amu) are initially at rest. They are accelerated through a potential V and then allowed to pass into a region of uniform magnetic field which is normal to the velocities of the particles. Within this region, the aparticle and the sulfur ion move in circular orbits of radii ra

M M 4 4,A thin rod of mass M and length a is free to rotate in horizontal plane about a fixed vertical axis passing through point O. A thin circular disc of mass M and of radius a4 is pivoted on this rod with its center at a distance a4 from the free end so that it can rotate freely about its vertical axis, as shown in the figure. Assume that both

A small object is placed at the center of a large evacuated hollow spherical container. Assume that the container is maintained at 0 K. At time t 0, the temperature of the object is 200 K. The temperature of the object becomes 100 K at t t and 50 K at t t. Assume the object and the container to be ideal black bodies. The heat capacity of the

Consider an undamped threedegreeof freedom springmass system shown in the following Figure. The motion of the system is completely described by the coordinates x(t), x (t), and x3 (t)which define the positions of the masses m, m and m3 at any time from the respective equilibrium position. xH m coo c. For the initial condition (0) For m m m 10kg,

Explain how the Na/P pump works in terms of cell concentrations and transport mechanisms.

There is a uniform electrostatic field in a region. The potential at various points on a small sphere centered at P, in the region, is found to vary between in the limits 589.0 V to 589.8 V. What is the potential at a point on the sphere whose radius vector makes an angle of 60 0 with the direction of the field (a) 589.5 V (b) 589.2 V (c) 589.4 V

A hollow metal sphere of radius 5 cm is charged such that the potential on its surface is 10 volts. The potential at the centre of the sphere is (a) zero (b) 10 volts (c) same as at a point 5 cm away from the surface (d) same as at a point 25 cm away from the surface

charge Q is divided into q and (Q q). If Q/q = x, such that the repulsion between them is maximum, find x (a) 1 (b) 2 (c) 3 (d) 4

A parallel plate capacitor having capacitance 12 pF is charged by a battery to a potential difference of 10 V between its plates. The charging battery is now disconnected and a porcelain slab of dielectric constant 6.5 is slipped between the plates. The work done by the capacitor on the slab is (a) 508 pJ (b) 692 pJ (c) 560 pJ (d) 600 pJ

An electric field of 1000 V/m is applied to an electric dipole at an angle of 45. The value of the electric dipole moment is 10 29 Cm. What is the potential energy of the electric dipole (a) 10 10 29 J (b) 7 10 27 J (c) 20 10 18 J (d) 9 10 20 J

Voltage rating of a parallel plate capacitor is 500 V. Its dielectric can withstand a maximum electric field of 106 V m 1 . The plate area is 10 4 m 2 . What is the dielectric constant if the capacitance is 15 pF? (given ? 0 = 8.86 10 12 C 2 N 1 m 2 ) (a) 3.8 (b) 8.5 (c) 6.2 (d) 4.5

The bob of a simple pendulum has a mass of 2 g and a charge of 5.0 C. It is at rest in a uniform horizontal electric field of intensity 2000 V m1. At equilibrium, the angle that the pendulum makes with the vertical is (take g = 10 m s2) (a) tan1 (0.2) (b) tan1 (0.5) (c) tan1 (2.0) (d) tan1 (5.0)

A parallel plate capacitor has 1 micro.F capacitance. One of its two plates is given + 2 ?C charge and the other plate, +4 ?C charge. The potential difference developed across the capacitor is (a) 3 V (b) 2 V (c) 5 V (d) 1 V

A capacitor with a capacitance 5 F is charged to 5 C. If the plates are pulled apart to reduce the capacitance to 2 F, how much work is done (a) 6.25 106 J (b) 3.75 106 J (c) 2.16 106 J (d) 2.55 106 J

A parallel plate capacitor of capacitance 90 pF is connected to a battery of emf 20 V. If a dielectric material of dielectric constant K = 5/3 is inserted between the plates, the magnitude of the induced charge will be (a) 1.2 nC (b) 0.3 nC (c) 2.4 nC (d) 0.9 nC

The energy stored in the electric field produced by a metal sphere is 4.5 J. If the sphere contains 4 ?C charges, its radius will be [Take: (1/4?? 0 ) = 9 x 10 9 Nm 2 /C 2 ] (a) 32 mm (b) 20 mm (c) 16 mm (d) 28 mm

A parallel plate capacitor is made of two circular plates separated by a distance of 5 mm and with a dielectric of dielectric constant 2.2 between them. When the electric field in the dielectric is 3 10 4 V/m, the charge density of the positive plate will be close to (a) 6 10 4 C/m 2 (b) 6 10 7 C/m 2 (c) 3 10 7 C/m 2 (d) 3 10 4 C/m 2

Two capacitors C 1 and C 2 are charged to 120 V and 200 V, respectively. It is found that by connecting them together the potential on each one can be made zero. Then (a) 9C 1 = 4C 2 (b) 5C 1 = 3C 2 (c) 3C 1 = 5C 2 (d) 3C 1 + 5C 2 = 0

An electric dipole is placed at an angle of 30 to a non-uniform electric field. The dipole will experience (a) a torque only (b) a translational force only in the direction of the field (c) a translational force only in a direction normal to the direction of the field (d) a torque as well as a translational force

A piece of copper and another of germanium are cooled from room temperature to 77 K, the resistance of (a) each of them increases (b) each of them decreases (c) copper decreases and germanium increases (d) copper increases and germanium decreases

In the common base mode of a transistor, the collector current is 5.488 mA for an emitter current of 5.60 mA. The value of the base current amplification factor (?) will be (a) 48 (b) 49 (c) 50 (d) 51

Carbon, silicon and germanium have four valence electrons each. At room temperature which one of the following statements is most appropriate? (a) The number of free electrons for conduction is significant only in Si and Ge but small in (b) The number of free conduction electrons is significant in C but small in Si and Ge (c) The number of free

In the ratio of the concentration of electrons that of holes in a semiconductor is 7/5 and the ratio of currents is 7/4 then what is the ratio of their drift velocities? (a) 4/7 (b) 5/8 (c) 4/5 (d) 5/4

The electrical conductivity of a semiconductor increases when electromagnetic radiation of a wavelength shorter than 2480 nm is incident on it. The bandgap in (eV) for the semiconductor is (a) 0.5 eV (b) 0.7 eV (c) 1.1 eV (d) 2.5 eV

A strip of copper and another germanium are cooled from room temperature to 80 K. The resistance of (a) each of these decreases (b) copper strip increases and that of germanium decreases (c) copper strip decreases and that of germanium increases (d) each of these increases.

The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the (a) crystal structure (b) variation of the number of charge carriers with temperature (c) type of bonding (d) variation of scattering mechanism with temperature

The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately (a) 540 nm (b) 400 nm (c) 310 nm (d) 220 nm

Photon of frequency has a momentum associated with it. If c is the velocity of light, the momentum is (a) hf/c (b) f/c (c) hfc (d) hf/c2

In a photoelectric effect experiment the threshold wavelength of light is 380 nm. If the wavelength of incident light is 260 nm, the maximum kinetic energy of emitted electrons will be given E (in eV) = [1237/?(in nm)] (a) 15.1 eV (b) 4.5 eV (c) 1.5 eV (d) 3.0 eV

When a certain photosensitive surface is illuminated with monochromatic light of frequency f, the stopping potential for the photocurrent is (-V0/2). When the surface is illuminated by monochromatic light of frequency f/2, the stopping potential is V0. The threshold frequency for photoelectric emission is (a) 4f/3 (b) 2f (c) 5f/3 (d) 3f/2

The maximum velocity of the photoelectrons emitted from the surface is v when the light of frequency n falls on a metal surface. If the incident frequency is increased to 3n, the maximum velocity of the ejected photoelectrons will be (a) more than ?3v (b) less than ?3v (c) v (d) equal to ?3v

Explain how the phenomenon of superconductivity can be understood in terms of quantum mechanics and describe how it can be applied in practical situations.

If 718 protons in a stream of protons pass through a tissue in one milli second, find the electric current passing through the tissue.

The speed of the particle, that can take discrete values, is proportional to (a) n-3/2 (b) n-1 (c) n1/2 (d) n

A silver sphere of radius 1 cm and work function 4.7 eV is suspended from an insulating thread in free space. It is under continuous illumination of 200 nm wavelength light. As photoelectrons are emitted, the sphere gets charged and acquires a potential. The maximum number of photoelectrons emitted from the sphere is A x 102 (where 1 < A < 10).

The work functions of silver and sodium are 4.6 eV and 2.3 eV, respectively. The ratio of the slope of the stopping potential versus frequency plot for Silver to that of Sodium is

A metal plate of area 1 x 10 -4 m 2 is illuminated by a radiation of intensity 16mW/m 2 . The word function of the metal is 5 eV. The energy of the incident photon is 10eV and only 10% of it produces photoelectrons. The number of emitted photoelectrons per second and their maximum energy, respectively will be [1 eV = 1.6 x 10 -19 J] (a) 10 14 and

When the wavelength of radiation falling on a metal is changed from 500 nm to 200 nm, the maximum kinetic energy of the photoelectrons becomes three times larger. The work function of the metal is close to (a) 0.81 eV (b) 1.02 eV (c) 0.52 eV (d) 0.62 eV

Two sources of light emit X-rays of wavelength 1 nm and visible light of wavelength 500 nm, respectively. Both the sources emit light of the same power 200 W. The ratio of the number density of photons of X-rays to the number density of photons of the visible light of the given wavelength is (a) 1/500 (b) 250 (c) 1/250 (d) 500

The ratio of the mass densities of nuclei 40 Ca and 16 O is close to (a) 1 (b) 0.1 (c) 5 (d) 2

For the uranium nucleus how does its mass vary with volume (a) m ? V (b) m ? 1/V (c) m ? ?V (d) m ? V2

Find the Binding energy per nucleon for 12050Sn. Mass of proton mp = 1.00783 U, mass of neutron mn = 1.00867 U and mass of tin nucleus mSn = 119.902199 U. (take 1U = 931 MeV) (a) 7.5 MeV (b) 9.0 MeV (c) 8.0 MeV (d) 8.5 MeV

The density of material in CGS system of units is 4gcm. In a system of units in which unit of length is 10 cm and unit of mass is 100 g, the value of density of material will be (a) 0.4 (c) 400 (b) 40 (d) 0.04

A rod PQ of mass M and length L is hinged at end P. The rod is kept horizontal by a massless string tied to point Q as shown in figure. When string is cut, the initial angular acceleration of the rod is (a) gL (c) 2g 3L (b) 2gL 2L

A simple pendulum performs simple harmonic motion about x 0 with an amplitude a and time period T. The speed of the pendulum at x will be 2 (b) T 3 (c) T (d) 3 2T

Under the influence of a uniform magnetic field a charged particle is moving in a circle of radius R with constant speed v. The time period of the motion (a) depends on both R and v (b) is independent of both R and v (c) depends on R and not on v (d) depends on v and not on R

An electron of mass m and a photon have same energy E. The ratio of deBroglie wavelengths associated with them is (a) () (b) (c) c(2mE) (d) (m) XC

a) NAND gate b) AND gate c) NOR gate d) OR gate

Which logic gate is represented by the following combination of logic gate

The time dependence of a physical quantity p is given by p p. exp ( a t), where a is a constant and t is the time. The constant a (a) is dimensionless (c) has dimensions T (b) has dimensions T (d) has dimensions of p

A solid homogeneous sphere of mass M and radius K is moving on a rough horizontal surface, partly rolling and partly sliding. During this kind of motion of the sphere (a) total kinetic energy is conserved (b) the angular momentum of the sphere about the point of contact with the plane is conserved (c) only the rotational kinetic energy about the

A wave travelling in the ve xdirection having displacement along ydirection as 1m, wavelength 2 m and frequency Hz is represented by TT (a) y sin (2x 2t) (b) y sin (10x 20t) (c) y sin (2x 2t) (d) y sin (x2t)

A long solenoid carrying a current produces a magnetic field B along its axis. If the current is double and the number of turns per cm is halved, the new value of the magnetic field is (a) 4B (b) B2 (c) B (d) 2B

Monochromatic radiation emitted when electron on hydrogen atom jumps from first excited to the ground state irradiates a photosensitive material. The stopping potential is measured to be 3.57 V. The threshold frequency of the materials is (a) 4 105 Hz (c) 1.6 x 105 Hz (b) 5 x 105 Hz (d) 2.5 x 10Hz

a) Define the number of degrees of freedom of a vibrating system. 2 marks b) Determine the equivalent spring constant of the system shown in Fig. 1(1). 4 marks,I) k 0000 k 0000 0000 0000 k k3 Figure 1 I) Spring system of question

If the velocity of a particle is v At Bt, where A and B are constants, then the distance travelled by it between 1s and 2s is 3 (a) A 4B 3 (c) A B 3 (b) 3A 7B A B (d) 3

A small object of uniform density rolls up a curved surface with an initial velocity v. It reaches upto a,3v 4g maximum height of with respect to the initial position. The object is a 2013 (a) solid sphere (b) hollow sphere (c) disc (d) ring

A standing wave is represented by y Asin (100t) cos (0.01x), where y and A are in millimetre, t in seconds and x is in metre. Velocity of wave is (a) 10 ms (b) 1 ms (c) 10 ms (d) not derivable from above data

When a charged particle moving with velocity v is subjected to a magnetic field of inductionB, the force on it is nonzero. This implies that (a) angle between V and B can have any value other than 90 (b) angle between V and B can have any value other than zero and 180 (c) angle between V and B is either zero or 180 (d) angle between V and B is

The photoelectric work function for a metal surface is 4.125 eV. The cut off wavelength for this surface is (a) 4125 (c) 6000 (b) 3000 (d) 2062.5

A bus is moving with a speed of 10 ms on a straight road. A scooterist wishes to overtake the bus in 100 s. If the bus is at a distance of 1 km from the scooterist, with what speed should the scooterist chase the bus (a) 40 ms (c) 10 ms (b) 25 ms (d) 20 ms

The density of a newly discovered planet is twice that of earth. The acceleration due to gravity at the surface of the planet is equal to that at the surface of the earth. If the radius of the earth is R, the radius of the planet would be (a) R (c) 4 R (b) 2 R (d) 14 R

A coil in the shape of an equilateral triangle of side I is suspended between the pole pieces of a permanent magnet such that B is in the plane of the coil. If due to a current i in the triangle a torque t acts on it, the side of the triangle is (a) (c)() 3 Bi, (b) 2 ( T (d) 1 3 B.i

An alpha nucleus of energy mv bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to (a) Ze (b) v

If the angle between the vectors Aand B is 0, the value of the product (B x A). A is equal to 2005 (a) BA sine (b) BA cose (c) BA sine cose (d) zero

A particle of mass m is thrown upwards from the surface of the earth, with a velocity u. The mass and the radius of the earth are, respectively, M and R. G is gravitational constant and g is acceleration due to gravity on the surface of the earth. The minimum value of u so that the particle does not return back to earth, is (a) 2GM R 2GM (b) R (c)

A coil of resistance 40002 is placed in a magnetic fiela. If the magnetic fluxo (wb) linked with the coil varies with time t (sec) as q 50f 4. The current in the coil at t 2 sec is (a) 0.5 A (c) 2 A (b) 0.1 A (d) 1 A

The approximate depth of an ocean is 2700 m. The compressibility of water is 45.4 x 10 Pa and density of water is 10 kgm.What fractional compression of water will be obtained at the bottom of the ocean (a) 1.0 x 10 (c) 1.4 x 10 (b) 1.2 10 (d) 0.8 x 10

When a body moves with a constant speed along a circle (a) its velocity remains constant (b) no force acts on it (c) no work is done on it (d) no acceleration is produced in it

Steam at 100C is passed into 20 g of water at 10C. When water acquires a temperature of 80C, the mass of water present will be Take specific heat of water 1 cal g C and latent heat of steam 540 cal g (a) 24 g (c) 42.5 g (b) 31.5 g (d) 22.5 g

In a circuit, L, C and R are connected in series with an alternating voltage source of frequency f. The current leads the voltage by 45. The value of C is 1 (a) (b) (c) (d) f(2fLR) 1 2f(2fLR) 1 f(2fLR) 1 2nf (2nfLR)

The binding energy of deuteron is 2.2 MeV and that of He is 28 MeV. If two deuterons are fused to form one He, then the energy released is (a) 23.6 MeV (c) 30.2 MeV (b) 19.2 MeV (d) 25.8 MeV

Three blocks with masses m, 2 m and 3 m are connected by strings as shown in the figure. After an upward force F is applied on block m, the masses move upward at constant speed v. What is the net force on the block of mass 2m (g is the acceleration due to gravity) F (a) 2 mg (c) 6 mg 2m 3m (b) 3 mg (d) zero

The maximum displacement of a massspringdamper system under harmonic force F(t) Fosin10t is X0.1m at resonance. If m 20kg, and damping ratio 0.25, determine (Hint use formula for magnification factor M) FIND Spring constant, Static deflection, and Amplitude of the force Fo M F(t)

The capacity of a parallel plate condenser is 10 F when the distance between its plates is 8 cm. If the distance between the plates is reduced to 4 cm then the capacity of this parallel plate condenser will be (a) 5 F (b) 10 F (d) 40 F (c) 20 F

The electric and the magnetic field associated with an E.M. wave, propagating along the zaxis, can be represented by ) E Eo, B Boj (b) E Eok, B Bo (c) E Eo, B Bo (d) E E), B Bok

A radio isotope X with a half life 1.4 10 years decays to Y which is stable. A sample of the rock from a cave was found to contain X and Y in the ratio 17. The age of the rock is (a) 1.96 10 years (c) 4.20 10 years (b) 3.92 10 years (d) 8.40 10 years

A mass of diatomic gas (y 1.4) at a pressure of 2 atmospheres is compressed adiabatically so that its temperature rises from 27C to 927C. The pressure of the gas in final state is (a) 28 atm (c) 256 atm (b) 68.7 atm (d) 8 atm

(a) V V V B (b) V V A (c) V A V B V V C (d) V V Vc A B,A, B and C are voltmeters of resistance R, 1.5 R and 3R respectively as shown in the figure. When some potential difference is applied between X and Y, the voltmeter readings are V, V, and V, respectively. Then R B to Y

Match the corresponding entries of column1 with column2 (Where m is the magnification produced by the mirror) Column1 Column2 (P) m 2(A) Convex mirror (Q) m 12 (B) Concave mirror (R) m 2 (C) Real image (S) m (D) Virtual image (a) P B and C, Q B and C, R B and D,S A and D. (b) PA and C, Q A and D, R A and B, S C and D (c) PA and D, Q B and C,

Halflives of two radioactive substances A and B are respectively 20 minutes and 40 minutes. Initially, the samples of A and B have equal number of nuclei. After 80 minutes the ratio of remaining numbers of A and B nuclei is (a) 116 (c) 14 (b) 41 (d) 11

A person holding a rifle (mass of person and rifle together is 100 kg) stands on a smooth surface and fires 10 shots horizontally, in 5 s. Each bullet has a mass of 10 g with a muzzle velocity of 800 ms. The final velocity,acquired by the person and the average force exerted on the person are (a)1.6 ms 8 N (c) 0.8 ms 8 N (b)0.08 ms 16 N (d)1.6 ms

The temperature of source and sink of a heat engine are 127C and 27C respectively. An inventor claims its efficiency to be 26, then (a) it is impossible (b) it is possible with high probability (c) it is possible with low probability (d) data are insufficient.

Consider the following two statements (A) Kirchhoffs junction law follows from the conservation of charge. (B) Kirchhoffs loop law follows from the conservation of energy. Which of the following is correct (a) Both (A) and (B) are wrong (b) (a) is correct and (B) is wrong (c) (a) is wrong and (B) is correct (d) Both (A) and (B) are correct

When a biconvex lens of glass having refractive index 1.47 is dipped in a liquid, it acts as a plane sheet of glass. This implies that the liquid must have refractive index. (a) equal to that of glass (b) less than one (c) greater than that of glass (d) less than that of glass

In forward biasing of the pn junction (a) the positive terminal of the battery is connected to p side and the depletion region becomes thick (b) the positive terminal of the battery is connected to n side and the depletion region becomes thin (c) the positive terminal of the battery is connected to n side and the depletion region becomes thick (d)

An engine pumps water through a hose pipe. Water passes through the pipe and leaves it with a velocity of 2 ms. The mass per unit length of water in the pipe is 100 kgm. What is the power of the engine (a) 400 W (c) 100 W (b) 200 W (d) 800 W

(a) 7.5 JK mol (c) 8.5 JK mol (b) 7.0 JK mol (d) 8.0 JK mol,0 g of a gas occupies 22.4 litres at NTP. The specific heat capacity of the gas at constant volume is 5.0JK. If the speed of sound in this gas at NTP is 952 ms, then the heat capacity at constant pressure is (Take gas constant R 8.3 JK mol )

The total power dissipated in watts in the circuit shown here is (a) 40 (c) 4 ww 452 www 602 ww 352 Hol 18 V (b) 54 (d) 16

The angle of a prism is A. One of its refracting surfaces is silvered. Light rays falling at an angle of incidence 2A on the first surface returns back through the same path after suffering reflection at the silvered surface. The refractive index u, of the prism is (a) 2 sin A (b) 2 cos A (d) tan A (c) COSA

The resistance of the four arms P, Q, R and S in a Wheatstones bridge are 10 ohm, 30 ohm, 30 ohm and 90 ohm, respectively. The e.m.f. and internal resistance of the cell are 7 volt and 5 ohm respectively. If the galvanometer resistance is 50 ohm, the current drawn from the cell will be (a) 0.2 A (c) 2.0 A (b) 0.1 A (d) 1.0 A