Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
COMEDK2024Evening ShiftPhysicsElectrostaticsActual

Three point charges are located on a circular arc at A, B and C as shown in the figure below. The total electric field at the centre of the arc (0) is

Options

  1. A15000 ~NC ⁻¹
  2. B5000 ~NC ⁻¹
  3. C20000 ~NC ⁻¹
  4. D10000 ~N C ⁻¹

Correct answer

B. 5000 ~NC ⁻¹

Step-by-step solution

r = 6.0 cm = 0.06 m, r^2 = 0.0036 m ^2 E_A = E_B = (9 10^9)(4.0 10⁻⁹) 0.0036 = 10000 N/C (away from A and B) E_C = (9 10^9)(2.0 10⁻⁹) 0.0036 = 5000 N/C (towards C, since charge is negative) By symmetry, A and B are 60° on either side of OC axis. Their perpendicular components cancel. Only components along OC axis are considered: E_ net = E_C - E_A 60° - E_B 60° = 5000 - 10000(0.5) - 10000(0.5) = 5000 - 5000 - 5000 = -5000 N/C Magnitude = 5000 NC ⁻¹

Practice Electrostatics on Quantrex Academy →

More from Electrostatics

A charge of 5 C is placed at the centre of a spherical shell S₁ of radius 10 cm. Now this system is enclosed inside another spherical shell S₂ of radius 20 cm. The ratio of the ele 2026Two point charges P = +25 C and Q = -16 C are placed 5 cm apart. Find the position of the point at which the resultant electric field is zero: 2026Bodies P, Q, R, S are labelled as having charges Q_P = 0.5 10⁻¹⁹C , Q_Q = 0.7 10⁻¹⁹C , Q_R = 2.1 10⁻¹⁹C , Q_S = 4.8 10⁻¹⁹C respectively. Select the body having the correct charge. 2026Uniform electric field of 5 10^3 ,NC⁻¹ is maintained in the positive Y direction. Now a point charge of 2 10⁻⁴C at rest is released from the origin. The kinetic energy attained by 2026A pith ball of mass 'm' gram and charge 'Q' is suspended using a mass less silk thread near a large charged conducting metal sheet of area 'A' and surface charged density ' '. If t 2026In a uniform electric field 10^6 N C⁻¹ an electric dipole of length 4 cm is placed with its axis making an angle 60^ with the electric field. If the dipole experiences a torque of 2026An electric field and magnetic field 1.8 10^4 Vm⁻¹ and 6 10⁻³ T respectively are applied simultaneously on an electron beam such that path of the beam remains undeviated, then the 2026A uniform electric field E = 3 i + 6 j + k passes through a closed cuboidal surface. One face of the cuboid has an area 4 m^2 and an outward unit normal given by 2 i +2 j +3 k 17 . 2026 Full Electrostatics list All COMEDK PYQs