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| IMPORTANT PHYSICS MCQ |
1. A car of mass 1000 kg moves on a circular path with constant speed of 16 m/s . It is turned by 90*
after travelling 628 m on the road. The centripetal force acting on the car is :
a) 160N b) 320 N c) 640N d) 1280N
2. A child is sitting on a swing . Its minimum and maximum heights from the ground are 0.75m and 2m
respectively, its maximum speed will be :
a) 5 m/ s b) 8 m/s c) 10 m/ s d) 15 m/ s
3. It is possible to recognise a person by hearing his voice even if he is hidden behind a solid wall . This is due to the fact that his voice :
a) has a definite capacity b) has a definite quality c) has a definite pitch d) can penetrate the wall
4. Rays of light strike a horizontal plane mirror at an angle 45* . A second mirror is arranged at an angle
Thita (Q ) with it . if the ray after reflection from the second mirror runs horizontally parallel to the first
then thita is :
a) 45 * b) 60 * c) 67*30 d) 135*
5. How should people wearing spectacles work with a microscope ?
a) they should keep on wearing their spectacles b) they should take off spectacles
c) they may keep on wearing or take off their spectacles, it makes no difference
d) they cannot use microscope at all
6. An uncharged capacitor with a solid dielectric is connected to a similar air capacitor charged to a
potential after sharing of charges becomes V then the dielectric constant of the dielectric must be:
a) V0 / V b) V /V0 c) (V0 - V ) / V d) V0 -- V / V0
7. A 3*C rise of temeperature is observed in a conductor by passing a certain a certain current. When
the current is doubled the rise of temperature will be :
a) 15* C b) 12*C c) 9*C d) 3*C
8. A car moves up a plane road. The induced emf in the axle connecting the two wheels is maximum
when it :
a) moves at the poles b) moves at equator c) remains stationary d) no emf is induced at all
9. In L -R circuit the current increases to three fourth of its maximum value in 4 s , then the time constant
of the circuit is :
a) 2 loge 2 b) 4 / loge 2 c) 2 / loge 2 d) loge 2 / 2
10. The percentage of mass which changes into energy in fission is of the order of :
a) 10 % b) 1 % c) 0.4 % d) 0.1 %
11. In a semiconductor diode p -side is earthed and n -side is applied to a potential of --2V . the diode
shall :
a) conduct b) not conduct c) conduct partially d) break down
12. An oscillator is basically an amplifier with gain :
a) less than unity b) more than unity c) zero d) 0.5
13. In a ripple tank when one pulse is sent every tenth of a second . the distance between consecutive
pulses is 30 min . In the same depth of water pulses are produced at half second intervals. What is the
new distance between consecutive pulses ?
a) 0.67 mm b) 6.0 mm c) 150 mm d) 600 mm
14. A double- convex thin lens made of glass of reflective index 1.6 has radius of curvature 15 cm each .
The focal length of this lens when immersed in a fluid of refractive index 1.63 is :
a) -- 407.5 cm b) + 407.5 cm c) 125 cm d) 25cm
15. If yellow light in Young's double slit experiment is replaced by red light , the fringe width will :
a) decrease b) remain unaffected c) increase d) first increase and then decrease
16. A galvanometer having a resistance 12ohm gives a full scale deflection for a current of 2.5mA. It is
converted into a voltmeter of range 10V . What is the net resistance of meter ?
a) 3898 ohm b) 4000 ohm c) 4 ohm d) 0.25 ohm
17. A body emts radiation when its temperature is :
a) greater than 0*C b) greater than 100*C c) greater than surrounding temperature d) Whatever
18. The frequency of the first line of Balmer series in hydrogen atom is V0 . The frequency v of the line
emmited by doubly ionised lithium atom lithium ion ( Li 3+ ) is :
a) 2 V0 b) 4 V0 c) 9 V0 d) V0 / 9
19. If p is momentum and c the speed of light , then the dimensions of pc are same as those of :
a) power b) force c) angular momentum d) energy
20. The value of resistance is 10.85452 and the value of current is 3.23 A . The potential difference is
35.02935 V . Its value in significant number would be :
a) 3.8 V b) 35.0 V c) 35.03 V d) 35.029 V
21. A body initially at rest is accelerate at the rate of 2 m/s² for 5s . If the body continues with uniform
velocity for next 10 s , the total distance covered by the body is :
a) 50 m b) 125 m c) 165 m d) 225m
22. In a compound microscope magnifying power is 95 and the distance of object from the objective
lens is 1 / 3.8 cm and the foacal length of objective lens is 1 / 4 cm the magnification of eye piece
is :
a) 5 b) 10 c) 100 d) insufficient data
23. Two polaroids are crossed . If now one of them is rotated through 30* and unpolarised light of
intensity Io is incident on the first polaroid , then the intensity of transmitted light will be :
a) Io / 4 b) 3Io /4 c) 3Io / 8 d) Io / 8
24. In a meter bridge with a standard resistance of 5 ohm in the left gap , the ratio of balancing lengths
on the meter brigade wire is 2 : 3 . The unknown resistance is :
a) 3.3 ohm b) 7.5 ohm c) 10 ohm d) 15 ohm
25. The inductance of a coil in which a current of 0.2 A is increasing at the rate of 0.5 A/s represents a
power flow of 0.5 w is :
a) 2H b) 5 H c) 10 H d) 20 H
26. The Rydberg constant for an electron revolving around hydrogen atom is R . The Rydberg constant
for electron revolving about 10 times ionised sodium atom will be :
a) R b) less tha R c) greater than R d) arbitrary
27. A radioactive element X with a half life of 2 h decays giving a stable element Y . After a time of t
hours the ratio of X to Y atoms is 1 : 7. Then is :
a) 4 b) 6 c) in between 4 and 6 d) 14
28. The output of a two input OR gate is 1 , if :
a) both inputs are zero b) either or both inputs are 1 c) only both inputs are 1
d) either input is zero
29. In n-p-n transistor circuit the collector current is 10 mA . If 90 % of the electrons emitted reach
collector then :
a) Ie = 1mA , Ib = 11 mA b) Ie = 11 mA , Ib = 1mA c) Ie = - 1mA , Ib = 9mA
d) Ie = 9 mA , Ib = 1mA
30. A cubical copper block has each side 2.0 cm . It is suspended by a string and submerged in oil
of density 820 kg /m³ . The tension in the string is : ( density of copper 8920kg/m³ , g = 10 m/s²)
a) 0.648 N b) 0.712 N c) 0.066 N d) 1.37 N
31. Critical temperature of CO2 is 31.2 * C . In summer the room temperature is 40*C :
a) CO2 cannot be liquefied b) Can be liquefied with increase of pressure
c) Can be liquefied with decrease of pressure d) Can be liquefied if temperature of CO2 is
decreased below 31.2 * C
32. The wavelength of light in air is 6000 A* and in medium its value is 4000 A* . It means that the refractive index of that medium with respect to air is :
a) 1.2 b) 2.4 c) 0.66 d) 1.5
33. A hollow prism is filled with water and placed in air . It will deviate the incident rays :
a) towards the base b) away from base c) parllel to base d) towards or away from base depending
on the location
34. In a compound microscope the intermediate image is :
a) virtual , erect and magnified b) real. erect and magnified c) real, inverted and magnified
d) virtual, erect and reudced
35. A convex lens has mean focal length 20 cm. The dispersive power of the material of the lens is 0.02 .
The longitudinal aberration for an object at infinity is :
a) 0.20 b) 0.40 c) 0.80 d) 1000
36. A uniform electric field and a uniform magnetic field are produced pointed in the same direction . An electron is projected with its velocity pointing in the same direction :
a) the electron will turn to its left b) the electron will turn to its right c) the electron velocity will
increase in magnitude d) the electron velocity will decrease in magnitude
37. At the magnetic pole of earth the value of angle of dip is :
a) 0* b) 30* c) 45 * d) 90 *
38. A north pole of 40 A-m is placed 20cm apart from a south pole of 80 A -m . Calculate the distance of a point from the south pole on the line joining the two poles wher the resultant field due to these poles is zero :
a) 8.2 cm towards north pole b) 8.2 cm away from north pole c) 48.2 cm towards north pole
d) 48.2 cm away from north pole
39. The mother and daughter elements with the emission of gamma rays are :
a) isotopes b) isobars c) isomers d) isodiapheres
40. Outside a nucleus :
a) neutron is stable b) neutron is unstable c) proton and neutron both are stable
d) proton and neutron both are unstable
41. When two semiconductor of p and n type are brought into contact they form a p-n junction which
like a :
a) conductor b) oscillatore c) amplifier d) rectifier
42. A cup of tea cools from 80* C to 60* C in 1 min. The ambient temperature is 30*C . In next 1 min its
temperature will be :
a) 40*C b) 45 * C c) 48 *C d) 42* C
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