physics

Questions Answers
1. The frequencies of two tuning forks are 480 cps and 480.05 cps respectively. When sounded together, after how much interval the maximum sound will become half if the minimum intensity is zero ? 5 s
10 s
20 s
0.025 s
2. A traveling wave passes a point of observation where in the time interval between two successive crests in found to be 0.2 s. Then the wave length of the wave is 5 m
the frequency of the wave is 5 cps
the velocity of the wave is 5 m/s
all the above
3. Ultrasonic waves are those waves to which human ear in sensitive
are of high velocity
are of high amplitude
none of these
4. The Laplace's correction for the expression for the velocity of sound given by Newton was needed because the sound waves are Longitudinal
propagate adiabatically
propagate isothermally
have long wave lengths
5. When two waves having constant phase difference produce interference, then there is loss of energy
gain in energy
redistribution of energy which does not depend on time
redistribution of energy which depends on time
6. The equation of a wave traveling on a string is given by y = 10 sin /2 (8t - x/8); where x and y are in cms. The velocity of the wave is 32 cms in the negative x-direction
32 cms in the positive x-direction
64 cms in the negative x-direction
64 cms in the positive x-direction
7. Equation of a progressive wave is given by
y = 0.2 cos (0.04t + 0.02x -/6);
where the distances are expressed in centimeter and time in second. The minimum distance between two particles having a phase difference of /2 is 4 cm
8 cm
25 cm
1.25 cm
8. By the principle of superposition, the resultant displacement in equal to the sum of the two displacements produced by two waves
vector sum of the two displacements produced by two waves
the difference between the two
displacements produced by two waves
none of these
9. The work done by the string of a simple pendulum during one complete oscillation is equal to the Total energy of the pendulum
KE of the pendulum
Pe of the pendulum
Zero
10. Which of the following is a necessary and sufficient condition for simple harmonic motion? Proportionality between restoring force and the displacement from the equilibrium
position.
Constant period
Constant acceleration
All of the above
11. Two charges 4q and q are kept "x" m apart. At what distance must be another charge "e" must be placed from the charge q, so that it is in equilibrium ? x/3
x/2
x/4
2x/3
12. A meatalic sphere has charge of 10 nC. A unit negative charge is moved from a point A to a point B, both I m away from the centre of the sphere, A being on the east side B being on the west side. The total work done is -2/10J
-1/10J
zero
cannot be calculated
13. The distance between two point charges 25 µC and 36 µC is 0.11m. At what point on the line joining the two charges in the intensity be zero ? At a distance of 0.05 m from 36 µC charge
At a distance of 0.05 m from 25 µC charge
At a distance of 0.11 m from 36 µC charge
At a distance of 0.11 m from 25 µC charge
14. If a glass rod is rubbed with silk, it acquires positive charge. This is because protons are added to it
electrons are added to it
electrons are removed from it
either (a) or (c)
15 The pressure-temperature relationship for an ideal gas undergoing adiabatic change is P1- T =constant
P/T =constant
P T1- =constant
PT1- = constant
16. The horizontal range of a particle thrown along a direction making an angle of 45degrees with the horizontal is equal to the vertical light
twice the vertical light
four times the vertical light
half the vertical light
17. A body is thrown vertically upwards. If air resistance is not taken into account, then the time of ascent is equal to the time of descent
greater than the time of descent
less than the time of descent
twice the time of descent
18. A stationary observer feels greater pitch of a sound while moving towards the source. The reason for this is increase in the pitch of the source
decrease in the wave length of the sound waves
increse in the velocity of sound
increase in the wave length of the sound waves
19. A blowing whistle is turned rapidly on a horizontal circle. A man standing outside the circle will be not hear it
listens uniform sound
listens one maxima and one minima
listens two maxima two one minima
20. When a light source is approaching an observer wavelength of light decreases
wavelength of light increases
wavelength of light remains unaltered
velocity of light increases
21. An ammeter gives a full scale definition for a current of 1A. To convert it into a 10A range ammeter, the ratio of its resistance and shunt resistance will be 1 : 9
10 : 1
9 : 1
1 : 10
22. Two unequal resistances are connected in parallel. Which of the following statement is correct ? The current through both in the same
The voltage drop across each is the same
The current through the higher resistance is high
None of these
23. A cell of emf E is connected across an external resistance R. If the terminal p.d., across the cell is V volts, the internal resistance of the cell is given by (E - V) R / V
(E - V) R / E
(V - E) R / V
(V - E) R / E
24. There are n similar conductors each of resistance R. When connected in parallel, the equivalent resistance is "x". When connected in series, the equivalent resistance will be x/n
nx
n2x
x/n2
25. Given three equal resistors, how many different combinations of all the three can be made ? 4
6
8
3
26. An infinite number of resistors are connected as shown in the figure. If R1 = 1 and R2 = 2 the equivalent resistance across the terminals AB is
Infinity
2
1
1.5
27. If the length of a potentiometer wire is increased, then the balancing length previously obtained will increase
decrease
remain unchanged
becomes two times
28. A current I flows through an infinitely long straight conductor. If "r" is the perpendicular distance of a point from the wire, then the magnetic induction B varies with "r" as B r0
B r -1
Br -2
B r -3
29. The field due to a long straight wire carrying a current I is proportional to I
I 3

1 / I
30. For a paramagnetic material the dependence of the magnetic susceptibility x on the absolute temperature T is given by x T
x 1/T
x eT
x is constant
31. Which of the following statement is true in the case of electric lines of force ? They are always parallel to one another
In a non-uniform electric field, the lines of force interest each other
They are always perpendicular to each another
They are always terminate at negative charges.
32. A variable capacitor and an electroscope are connected in parallel to a battery. The reading of the electroscope would be decreased by increasing the area of the overlap plates of the capacitor
placing a pile of paraffin wax between the plates of capacitor
decreasing the distance between the plates
decreasing the battery potential
33. A parallel plate capacitor has a capacitance of 50 µF with air as dielectric and 110 µF with an oil as a dielectric. The dielectric constant of the oil is 2.2
1.1
0.5
1
34. A parallel plate capacitor has a capacitance of 10 µF with air as dielectric. The area of the capacitor is divided into two equal halves and filled with two media having dielectric constants 2 and 4. The capacitance of the system will now be 10 µF
30 µF
5 µF
20 µF
35. The capacity of a spherical conductor of radius R is given by R / 4
4 / R
4 R
1 / 4 R
36. . An infinite number of capacitors each of capacitance 1µF are connected to parallel branch contains 2n capacitors connected in series where n=0, 1, 2, 3, 4,.. The equivalent capacitance of the combination is equal to 1µF
2µF
0.5µF
infinity
37. The value of a resistance with a colour code yellow, violet and gold is 47± 5 %
4.7 ± 5 %
4.7 ± 20 %
0.47 ± 5
38. A current of 4.8 A is flowing through a conductor. The number of electrons passing per second across a point is 3 X 10 19
7.68 X 10 20
3 X 10 20
7.68 X 10 19
39. The specific resistance of a material is
0.5 µ-m. The resistance of a cube of length
0.5 m of the material will be .05
10 -3
10 -5
10 -6
40. Four resistance 10 , 2, 5 and 25 are connected in cyclic order in the form of a Wheatstone's bridge. A current of 1.4 A enters at the junction of 10 and 25 resistors. The current through the 2 resistor is 1 A
1.2 A
1.4 A
none of these
41. For a telescope to have a large resolving power, the focal length of its objective should be large
focal length of its eye-piece should be large
focal length of its objective should be small
aperture of its objective should be large
42 A light wave has a frequency of 4x10 14 Hz and a wavelength of 5x10-7 metres in a medium. The refractive index of the medium is 1.5
1.33
1.6
2.4
43. A person sees his virtual image by holding a mirror very close to his face. When he moves the mirror away from his face, the image becomes inverted. What type of mirror is he using ? Plane mirror
Convex mirror
Concave mirror
None of these
44. In electromagnetic radiations magnetic field remains unchanged while electric field changes with time
electric field remains unchanged while electric field changes with time
both electric and magnetic fields are time dependant
neither electric nor magnetic fields are time dependant
45. An inductance of 1 mH, a capacitor of 10µF and a resistance of 50 are connected in series. The reactances of inductor and capacitor are same. The reactance of either of them will be 100
50
30
10
46. The power factor in a circuit connected to an ac power supply has a value which is unity when the circuit contains an ideal capacitor only
unity when the circuit contains an ideal resistance only
unity when the circuit contains an ideal inductance only
zero when the circuit contains an ideal resistance only
47. In a transformer the core is made up of soft iron to reduce hysteresis loss
eddy current loss
magnetic flux linkage
all the above
48. A coil and bulb are connected in series with a de source. When a soft core is inserted into the coil, intensity of the bulb decreases
intensity of the bulb increases
intensity of the bulb remains unchanged
the bulb ceases to glow
49. In a transformer, the coefficient of mutual induction between the primary and secondary coil is 0.2 H. When a current changes by 5 amperes/second, the emf induced in the secondary is 1V
5V
20 V
15V
50.
A rod of length 0.4 m moves in a direction perpendicular to a magnetic field of strength
1.2 T. The emf induced in the moving rod is 2.4 V. What is the speed of the rod ? 0.5 m/s
2.5 m/s
7.5 m/s
5 m/s
51. The objective of a telescope has a focal length of 1.2 m and diameter 0.05 m. The focal length of the eye-piece is 0.05m. The magnifying power of the telescope for distant object is 10
24
60
100
52. The momentum of a photon is 3.3 *10 -29 kg-m/s. Its frequency will be 3 x10 13 Hz
6 x10 13 Hz
1x 10 13 Hz
1.5 x10 13 Hz
53. The de Broglie wavelength of a mass 1 kg moving with a speed of 1 m/s is 6.6 x10 -34 m
6 x10-34 m
6.6x10 -10 m
6x 10 -10 m
54. Which experiment indicates that the whole positive charge of an atom is concentrated in the nucleus of size10 -14 m ? Madam Curie's experiment with radioactivity
Rutherford's experiment on µ-ray scattering
Faraday's experiment on electrolysis
Thomson's experiment to determine the specific charge of electron
55. The half life period of radium is 1600 years. Its average life time is 1600 years
1/1600 years
2319 years
1/2319 years
56. In the reaction
92 U 235 + 0 n1-->51 Xe 140 + z SrA + 2 0 n1 + photon the values of Z and A are 38, 94
39, 94
38, 95
41, 94
57. The energy required to knock out the electron in the third orbit of a hydrogen atom is equal to 13.6 eV
+ 13.6/9 eV
+ 13.6/3 eV
none of these.
58. When the electrical conductivity of a semiconductor is due to the breaking up of its covalent bonds only, then the semiconductor ids said to be a p-type semiconductor
a n-type semiconductor
an intrinsic semiconductor
a extrinsic semiconductor
59. Electron, proton, neutron and -particle are moving with equal velocity. Which one of them will have the smallest wave length ? Electron
Proton
Neutron
a-particle
60. Fusion reaction takes place at very high temperatures because atoms are ionized at high temperatures
KE is high enough to overcome the electrostatic force of repulsion
Molecules break up at high temperatures
All the above