As you want to get WBJEE Sample Question Paper for doing preparation of this exam so here I am giving you some questions of that paper:
WBJEE Sample Question Paper
1. The number of free electrons per 10 mm of an ordinary copper wire is 2 x 1021. The average
drift speed of the electrons is 0.25 mm/s. The current flowing is:
A. 0.8 A B. 8 A C. 80 A D. 5 A
2. Which of the following cells is more likely to be damaged due to short circuiting?
A. Daniel B. Dry C. Acid D. Fuel
3. A gas expands from 5 litre to 105 litre at a constant pressure 100N/m2. The work done is
A. 1 Joule B. 4 Joule C. 8 Joule D. 10 Joule
4. The Helium nuclei can be formed from
A. Hydrogen nuclei by process of chain reactionB. Hydrogen nuclei through nuclear fission
C. Hydrogen nuclei through nuclear fusion D. None of these
5. In the atom bomb dropped by Americans in 1945 on Nagasaki, Japan, the fissionable material
used was
A. Helium 4 B. Plutonium 239 C. Uranium 235 D. Uranium 233
6. The engine of a truck moving a straight road delivers constant power. The distance travelled
by the truck in time t is proportional to
A. t B. t 2 C. √t D. t 3/2
7. The velocity of electron in ground state of
hydrogen atom is
A. 2 x 105
m/s
B. 2 x 106
m/s
C. 2 x 107
m/s
D. 2 x 108
m/s
8. The radius of the first orbit of the electron in a hydrogen atom is 5.3 x 10-11 m; then the radius
of the second orbit must be
A. 15.9 x 10-11 m B. 10.6 x 10 m C. 21.2 x 10-11 m D. 42.4 x 10-11 m
9. A person pushes a rock of 1010Kg mass by applying a force of only 10N for just 4 seconds.
The work done is
A. 1000 Joule B. 0 J C. nearly zero D. positive
10. One can take pictures of objects which are completely invisible to the eye using camera films
which are sensitive to
A. ultra-violet rays B. sodium light C. visible light D. infra-red rays
11. Light from a 100 watt filament bulb is passed through an evacuated glass tube containing
sodium vapour at a high temperature. If the transmitted light is viewed through a spectrometer,
we will observe
A. D1 and D2 lines of sodium with good
intensity
B. dark lines where D1 and D2 lines should have
been observed
C. continuous radiation from the bulb only D. the entire emission spectrum of sodium
12. Under the action of a constant force, a
particle is experiencing a constant acceleration.
The power is
A. zero B. positive
C. negative D. increasing uniformly
with time
13. If in a plane convex lens the radius of curvature of the convex surface is 10 cm and the focal
length of the lens is 30 cm, the refractive index of the material of the lens will be
A. 1.5 B. 1.66 C. 1.33 D. 3
14. A plane convex lens has radius of curvature 30 cm. If the refractive index is 1.33, the focal
length of lens is
A. 10 cm B. 90 cm C. 30 cm D. 60 cm
15. A beam of light is converging towards a point I on a screen. A plane parallel plate of glass
(thickness in the direction of the beam = t, refractive index = µ ) is introduced in the path of the
beam. The convergence point is shifted by
A. t (µ - 1) away B. t (1 + 1/µ ) away C. t (1 - 1/µ ) nearer D. t (1 + 1/µ ) nearer
16 . In Young's double silt experiment the separation between the silts is halved and the distance
between the silts and screen is doubled. The fringe width will be
A. unchanged B. halved C. doubled D. quadrupled
17. Wavelength of red light is λ r, violet rays is λ v and X -ray is λ x then the order of
wavelengths is
A. λ x >λ v >λ r B. λ v >λ x >λ r C. λ r >λ x >λ v D. λ r >λ v >λ
18. The amount of work done by the labourer
who carries n bricks, each of mass m, to the roof
of a house whose height is h is
A. n mgh B. mgh/n C. zero D. ghn/m
19. In LCR circuit in the state of resonance, which of the following statements is correct ? (cos
φ)=
A. 0 B. 0.5 C. 1 D. None of these
20. In LCR circuit, phase difference between voltage and current cannot be
A. 80° B. 90° C. 145° D. 0°
21. If speed is plotted along x-axis and Kinetic energy against y-axis, then the graph obtained has
a shape similar to that of
A. circle B. ellipse C. hyperbola D. parabola
22. A magnetic needle lying parallel to a magnetic field requires w units of work to turn it
through 60°. The torque needed to maintain the needle in this position will be
A. (√ 3) w B. w
C. (√ 3w)/2 D. 2w
23. A vertical straight conductor carries a
current vertically upwards. A point p lies to the
east of it at a small distance and another point Q
lies to west of it at the same distance. The
magnetic field at p is
A. greater than at Q B. same as at Q
C. less than at Q
D. greater or less at Q
depending upon the
strength of the current
24. In a parallel arrangement if (R1 > R2), the power dissipated in resistance R1 will be
A. less than R2 B. same as R2 C. more than R2 D. none of these
25. For a fuse wire to be installed in the supply line in a house which one of the following is
immaterial ?
A. the specific resistance of the material of the
fuse wire B. the diameter of the fuse wire
C. the length of the fuse wire D. none of these
26. If V is voltage applied, Ea is emf drop across the armature, the armature current of a d.c.
motor Ia is given by
A. (V + Ea)/Ra B. Ea/Ra C. V- Ea/Ra D. V/Ra
27. The current of 2.0 amperes passes through a cell of e.m.f. 1.5 volts having internal resistance
of 0.15Ω . The potential difference measured in volts across both the terminals of the cell will be
A. 1.35 B. 1.50 C. 1.00 D. 1.20
28. In this circuit, current ratio i1/i2 depends upon
A. R1, R2
and R
B. R, R1,
R2 and E
C. R1 and
R2 D. E and R
29. A cell of emf E is connected across a resistance r. The potential difference between the
terminals of the cell is found to be V. The internal resistance of the cell must be
A. 2(E - V)V/r B. 2(E - V)r/E C. (E - V) r/V D. (E- V)/r
30. Copper and germanium are both cooled to 70 K from room temperature, then
A. resistance of copper increases while that of
germanium decreases
B. resistance of copper decreases while that of
germanium increases
C. resistance of both decreases D. resistance of both increases
31. The potential difference between the points A and B of the electrical circuit given is
A. 1.5 V B. 1.0 V
32. A moving coil galvanometer has a resistance
of 9.8Ω and gives a full scale deflection when a
current of 10 mA passes tbrough it. The value of
the shunt required to convert it into a mini
ammeter to measure current upto 500 mA is
A. 0.02Ω B. 0.2Ω C. 2Ω D. 0.4Ω
33. The total electrical resistance between the points A and B of the circuit shown in the figure is
A. 9.02 Ω A. 15 Ω
C. 30 Ω D. 100 Ω
34. If the plates of a charged parallel plate capacitor are pulled away from each other
A. capacitance
increases B. energy increases C. voltage increases D. voltage decreases
35. A parallel plate capacitor is charged by connecting its plates to the terminals of a battery. The
battery remains connected and a glass plate is interposed between the plates of the capacitor,
then
A. the charge on plates will be reduced
B. the charge on plates will increase
C. the potential difference between the plates of the capacitor will be reduced
D. the potential difference between the plates of the capacitor will increase
36. A person weighing 70Kg wt lifts a mass of 30 Kg to the roof of a building 10 m high. If he
takes 50 sec to do so,then the power spent is
A. 19.6 W B. 196 W C. 300 W D. 50 W
37. Work done in carrying a charge q from A to B along a semi-circle is
A. 2πrq B. 4πrq
C. πrq D. 0
38. A particle A has charge +q and particle B has charge +4q with each of them having the same
mass m. When allowed to fall from rest through same electrical potential difference, the ratio of
their speed VA :
VB will become
A. 2:1 B. 1:2 C. 1:4 D. 4:1
39. The electric field at a small distance R from an infinitely long plane sheet is directly
proportional to
A. R2/2 B. R/2 C. R-2 D. none of these
40. In the diagram, the electric field intensity will be zero at a distance
A. between -q and +2q charge B. towards +2q on the line drawn
C. away from the line towards
+2q D. away from the line towards -q
41. Wein's displacement law is given by
A. λ m =
constant
B. T/λ m =
constant
C. λ m T =
constant
D. T = λ m
= constant
42. If two electrons are forced to come closer to each to each other, then the potential energy
A. becomes zero B. increases C. decreases D. becomes infinite
43. The specific heat at constant pressure is greater than that of the same gas at constant volume
because
A. at constant volume work is done in expanding the gas
B. at constant pressure work is done in expanding the gas
C. the molecular attraction increases more at constant pressure
D. the molecular vibration increases more at constant pressure
44. The specific heats of CO2 at constant pressure and constant volume are 0.833 J/kg.K and
0.641 J/kg.K respectively. If molecular weight of CO2 is 44, what is the universal constant R?
A. 4.19 x 107 erg/cal B. 848.8 J/gm/K C. 8.448 J/mol/K D. 4.19 J/cal
45. The freezing point of the liquids decreases when pressure is increased, if the liquid
A. expands while freezing B. contracts while freezing
C. does not change in volume while freezing D. none
46. The equation of a transverse wave on a
stretched string is given by
y = 0.05 sin π (2t/0.002 -x/0.1 ) where x and y
are expressed in metres and t in sec.
The speed of the wave is
A.100
m/sec B. 50 m/s C. 200 m/s D. 400 m/s
47. The ratio of velocity of the body to the velocity of sound is called
A. Magic number B. Laplace number C. Natural number D. Mach number
48. Television signals on earth cannot be received at distances greater than 100 km from the
transmission station. The reason behind this is that
A. the receiver antenna is unable to detect the signal at a distance greater than 100 km
B. the TV programme consists of both audio and video signals
C. the TV signals are less powerful than radio signals
D. the surface of earth is curved like a sphere
49. A ball is thrown from a height of h m with an initial downward velocity v0. It hits the ground,
loses half of its Kinetic energy & bounces back to the same height. The value of v0 is
A. √2gh B. √gh C. √3gh D. √2.5gh
50. A thick rope of rubber of density 1.5 x 103
kg/m3 and Young's modulus 5 x 106 N/m2, 8m in
length, when hung from ceiling of a room, the
increase in length due to its own weight is
A. 9.6 x 10-
3m
B. 19.2 x
10-5m
C. 9.6cm D. 9.6mm
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