NEET Physics - New - Electrostatics

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Question - 1

Suppose the charge of a proton and an electron differ slightly. One of them is - e, the other is (e). If the net f electrostatic force and gravitational force between two hydrogen atoms placed at a distance d (much greater than atomic size) apart is zero, then ∆e is of the order of: [Given mass of hydrogen mh = 1.67 X 10-27 kg]

  • A 10-23 C
  • B 10-37 C
  • C 10-47 C
  • D 10-20 C

Question - 2

An electric dipole is placed at an angle of 300 with an electric field intensity 2.0 X 105 N/C. It experiences a torque equal to 4 N m. The charge on the dipole, if the dipole length is 2 cm, is:

  • A 8 mC
  • B 2 mC
  • C 5 mC
  • D 7 μC

Question - 3

The electric field in a certain region is acting radially outward and is given by E = Ar. A charge contained in a sphere of radius 'a' centred at the origin of the field, will be given by:

  • A \(4\pi { \varepsilon }_{ 0 }A{ a }^{ 3 }\)
  • B \({ \varepsilon }_{ 0 }A{ a }^{ 3 }\)
  • C \(4\pi { \varepsilon }_{ 0 }A{ a }^{ }\)
  • D \({ \varepsilon }_{ 0 }{ a }^{ 2 }\)

Question - 4

In a region the potential is represented by V(x, y, z) = 6x - 8xy - 8y + 6yz, where V is in volts and x, y, z are in meters. The electric force experienced by a charge of 2 coulomb situated at point (1, 1, 1) is:

  • A \(6\sqrt { 5 } N\)
  • B 30 N
  • C 24 N
  • D \(4\sqrt { 35 } N\)

Question - 5

Two metallic spheres of radii 1 cm and 3 em are given charges of -1 x 10-2 C and 5 x 10-2 C, respectively. If these are connected by a conducting wire, the final charge on the bigger sphere is:

  • A 3 X 10-2 C
  • B 4 X 10-2 C
  • C 1 X 10-2 C
  • D 2 X 10-2 C

Question - 6

A charge Q is enclosed by a Gaussian spherical surface of radius R. If the radius is doubled, then the outward electric flux will:

  • A increase four times
  • B be reduced to half
  • C remain the same
  • D be doubled

Question - 7

Two positive ions, each carrying a charge q, are separated by a distance d. If F is the force of repulsion between the ions, the number of electrons missing from each ion will be (e being the charge on an electron):

  • A \(4\pi { \varepsilon }_{ 0 }{ Fd }^{ 2 }/{ e }^{ 2 }\)
  • B \(\sqrt { 4\pi { \varepsilon }_{ 0 }Fe^{ 2 }/d^{ 2 } } \)
  • C \(\sqrt { 4\pi { \varepsilon }_{ 0 }{ Fd }^{ 2 }/{ e }^{ 2 } } \)
  • D \(4\pi { \varepsilon }_{ 0 }{ Fd }^{ 2 }/{ q }^{ 2 }\)

Question - 8

Three concentric spherical shells have radii a, b and c (a < b < c) and have surface charge densities σ, - σ and σ respectively. If VA, VB and VC denote the potentials of the three shells, then for c = a + b, we have:

  • A VC = VB ≠ VA
  • B VC ≠ VB ≠ VA
  • C VC = VB = VA
  • D VC = VA ≠ VB

Question - 9

Two charges q1 and q2 are placed 30 cm apart, shown in the figure. A third charge q3 is moved along the arc of a circle of radius 40 cm from C to D. The change in the potential energy of the system is q3/4\(\pi \)ε0 x k, where k is:

  • A 8q2
  • B 8q1
  • C 6q2
  • D 6q1

Question - 10

A bullet of mass 2 gm is having a charge of 2\(\mu \)C. Through what potential difference must it be accelerated, starting from rest, to acquire a speed of 10m/s.

  • A 5 kV
  • B 50 kV
  • C 5 V
  • D 50 V