A flat, square surface with sides of length L is described by the equations x = L, 0 ≤ y ≥ L, 0 ≤ z ≥ L. The electric flux through the square due to a positive point charge q located at the origin (x = 0, y = 0, z = 0) is

Q.A flat, square surface with sides of length L is described by the equations x = L, 0 ≤ y ≥ L, 0 ≤ z ≥ L. The electric flux through the square due to a positive point charge q located at the origin (x = 0, y = 0, z = 0) is
(a) q/4εo
(b) q/6εo
(c) q/24εo
(d) q/48εo
Ans: C

A spherical shell of radius R = 1.5cm has a charge q = 20μC uniformly distributed over it. The force exerted by one half over the other half is

Q.A spherical shell of radius R = 1.5cm has a charge q = 20μC uniformly distributed over it. The force exerted by one half over the other half is
(a) zero
(b) 10-2 N
(c) 500 N
(d) 2000 N
Sol: E= σ/2ℇ0 , Pressure P = σ2/2ℇ0
Force F = P × πR2
= σ2/2ℇ0 × πR2
= (q /4 πR2 )2 πR2/2ℇ0
Putting the given value
Ans: D

In a region of space, the electric field is given by E ⃗=8i ̂+4j ̂+3k ̂. The electric flux through a surface of area 100 units in the xy plane is

Q. In a region of space, the electric field is given by E ⃗= 8i ̂+4j ̂+3k ̂. The electric flux through a surface of area 100 units in the xy plane is
(a) 800 units
(b) 300 units
(c) 400 units
(d) 1500 units
Ans: B

Consider two concentric spherical surfaces, S1 with radius a and S2 with radius 2a, both centered at the origin. There is a charge +q at the origin and there are no other charges. Compare the flux 1 through S1 with the flux 2 through S2

Q.Consider two concentric spherical surfaces, S1 with radius a and S2 with radius 2a, both centered at the origin. There is a charge +q at the origin and there are no other charges. Compare the flux φ1  through S1 with the flux φ2 through S2.
(a) φ1 = 4φ2
(b) φ1 = 2φ2
(c) φ1 = φ2
(d) φ1 = φ2 /2
Ans: C

A cylinder of radius R and length l is placed in a uniform electric field E parallel to the axis of the cylinder. The total flux over the curved surface of the cylinder is

Q. A cylinder of radius R and length l is placed in a uniform electric field E parallel to the axis of the cylinder. The total flux over the curved surface of the cylinder is
(a) zero
(b) πR²E
(c) 2 πR²E
(d) E/πR²
Ans: A