ECAT Physics Online Test With Answers

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ECAT Physics Online Test

Sr. # Questions Answers Choice
1 If we increase the distance between two plates of the capacitor, the capacitance will Increase Decrease Remain same First increase then decrease
2 A capacitor is charged with a battery and then it is disconnected. A slab of dielectric is now inserted between the plates, then The charge in the plates reduces and potential difference increase Potential difference between the plates increase, stored energy decreases and charge remains the same Potential difference between the plates decreases and charge remains unchanged None of the above
3 One moving a charge of 20 coulombs by 2 cm, 2 J of work is done, then the potential difference between the points is 0.1 V 8 V 2 V 0.5 V
4 An alpha particle is accelerated through a potential difference of 106volt. Its kinetic energy will be 1 MeV 2 MeV 4 MeV 8 MeV
5 A proton is about 1840 times heavier than an electron. When it is accelerated by a potential difference of 1 KV, its kinetic energy will be 1840 KeV 1/1840 KeV 1 KeV 920 KeV
6 Electric potential of earth is taken to be zero because the earth is good Semiconductor Conductor Insulator Dielectric
7 In bringing an electron towards another electron, electrostatic potential energy of system Decreases Increases Remains uncharged Becomes zero
8 The electric potential at the surface of an atomic nucleus (Z = 50) of radius 9.0 x 10-15 is 9 x 10<sup>5</sup>V 9 V 8 x 10<sup>6</sup>V 80 V
9 At any point on the right bisector of the line joining two equal and opposite charges At electric field is zero The electric potential is zero The electric potential decreases with increasing distance from the centre The electric field is perpendicular to the line joining the charges
10 Some charge is being given to a conductor. Then its potential Is maximum at surface Is maximum at centre Is remain same throughout the conductor Is maximum somewhere between surface and centre
11 Two conductors having the same type of charges are connected by a conducting wire. There would not be any amount of charges on them if They have the same potential They have the same amount of charge They have the same capacity They have the same shape
12 A cube of metal is given a positive charge Q. For the above system, which of the following statements is true? Electric potential at the surface of the cube is zero Electric potential within the cube is zero Electric filed is normal to the surface of the cube Electric filed varies within the cube
13 If the distance of separation between two chares is increased, the electrical potential energy of the system will Increase Decrease May increase or decrease Remain the same
14 If a charged spherical conductor of radius 10 cm has potential V at a point distance 5 cm from its centre, then the potential at a point distance 15 cm from the centre will be 1/3 V 2/3 V 3/2 V 3V
15 Equal charges are given to two spheres of different radii. The potential will Be more on the smaller sphere Be more on the bigger sphere Be equal on both the sphere Depend on the nature of the material of the sphere
16 An electron of charge e coulomb passes through a potential difference of V volts its energy in joules will be V/e eV e/V V
17 The electric field due to an infinite long thin wire at a distance R varies as 1/R 1/R<sup>2</sup> R R<sup>2</sup>
18 A wire is bent into a ring of radius R is given a charge q. The magnitude of the electrical field at the centre of the ring is Two 1/2 Zero 3/2
19 The excess (equal in number) of electrons that must be placed on each of two small spheres spaced 3 cm apart, with force of repulsion between the spheres to be 10-19N, is 25 225 625 1250
20 Two point charges A and B separated by a distance R attract each other with a force of 12 x 10-3N. The force between A and B when the charges on them are doubled and distance is halved 1.92 N 19.2 N 12 N 0.192 N
21 A charge Q is divided into two parts q and Q - q and separated by a distance R. The force of repulsion between them will be maximum when q = Q/4 q = Q/2 q = ! None of these
22 The force of repulsion between two point charges is F, when these are at a distance 0.1 m apart. Now the point charges are replaced by sphere of radii 5 cm each having the same charge as that of the respective point charges. The distance between their centre is again kept 0.1 m ; then the force of repulsion will Increase Decrease Remain F Become 10F/9
23 A point charge Q is placed at the mid-point of a line joining two charges. 4q and q. if the net force on charge q is zero. then Q must be equal to -q +q -2q +4q
24 A point charge A of charge +4μC and another B of charge -1μC are placed in air at a distance 1 m apart. Then the distance of the point on the line joining the charge B, where the resultant electric field is zero, is (in m) 2 1 0.5 1.5
25 A hollow insulated conduction sphere is given a positive charge of 10μC. What will be the electric field at the centre of the sphere if its radius is 2 meters? Zero 5<span style="color: rgb(34, 34, 34); font-family: &quot;Times New Roman&quot;; font-size: 24px; text-align: center; background-color: rgb(255, 255, 248);"><b>μ</b></span>C m<sup>-2</sup> 20<span style="color: rgb(34, 34, 34); font-family: &quot;Times New Roman&quot;; font-size: 24px; text-align: center; background-color: rgb(255, 255, 248);"><b>μ</b></span>C m<sup>-2</sup> 8<span style="color: rgb(34, 34, 34); font-family: &quot;Times New Roman&quot;; font-size: 24px; text-align: center; background-color: rgb(255, 255, 248);"><b>μ</b></span>C m<sup>-2</sup>
26 An electric dipole is at the centre of a hollow sphere of radius r. The total normal electric flux through the sphere is (here Q is the charge and d is the distance between the two charges of the dipole) Q/4<i style="box-sizing: border-box; color: rgb(34, 34, 34); font-family: &quot;Times New Roman&quot;; font-size: 18px; background-color: rgb(255, 255, 248);">π</i>r<sup>2</sup> 2Q/4<i style="box-sizing: border-box; color: rgb(34, 34, 34); font-family: &quot;Times New Roman&quot;; font-size: 18px; background-color: rgb(255, 255, 248);">π</i>r<sup>2</sup> Q.d Zero
27 Consider a spherical shell of metal at he centre of which a positive point charge is kept The electric filed is zero outside the shell The electric field is zero everywhere The electric field is zero in the region inside the shell The electric field is non-zero in both regions outside and inside the shell
28 The unit of intensity of electric field is newton/coluomb jule/coluomb volt x metre newton/metre
29 In a Milikian's oil drop experiment the charge on an oil drop is calculated to be 6.35 x 10-19C. The number of excess electrons on the drop is 3.9 4 4.2 6
30 Two point charge +3μC and +8μC repel each other with a force of 40 N. If a charge of -5μC is added to each of them, then the force between then will become -10 N +10 N +20 N -20 N
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