Why must electrostatic field at the surface of a charged conductor be normal to the surface at every point ? Give reason.
If the electric field was not normal to the surface, then it would have a component along the surface which would cause work to be done in moving a charge on an equipotential surface.
Detailed Answer :
Equipotential lines are curved lines with similar altitude that pertains to electric potential or voltage. These lines are always perpendicular to electric field which create equipotential surfaces in three dimensions. The movement of charge along equipotential surface requires no work as movement is perpendicular to electric field. As work done in moving test charge along equipotential surface is zero, there appear fixed potential values across every point on equipotential surface, so
W = Fscosθ =0
where,
F = Electric force
s = Magnitude of displacement of charge
In case of non-zero displacement, it exists only when
cos θ = 0
θ= 90°
Hence, force acting on point charge is perpendicular to equipotential surface.
Detailed Answer :
Equipotential lines are curved lines with similar altitude that pertains to electric potential or voltage. These lines are always perpendicular to electric field which create equipotential surfaces in three dimensions. The movement of charge along equipotential surface requires no work as movement is perpendicular to electric field. As work done in moving test charge along equipotential surface is zero, there appear fixed potential values across every point on equipotential surface, so
W = Fscosθ =0
where,
F = Electric force
s = Magnitude of displacement of charge
In case of non-zero displacement, it exists only when
cos θ = 0
θ= 90°
Hence, force acting on point charge is perpendicular to equipotential surface.
Why are electric field lines perpendicular at a point on an equipotential surface of a conductor ?
For any charge configuration, equipotential surface through a point is normal to the electric field. Justify.
The electric potential due to point charge 3 nC at distance of 9 cm is
(a) 270 v
(b) 3 v
(c) 300 v
(d) 30 v
Electric potential at a distance r from the point charge is proportional to
1. \(r^2\)
2. r-1
3. r0
4. r+1
State which of the two a capacitor or an inductor, tends to become SHORT when the frequency of the applied alternating voltage has a high value.
Why is the use of ac voltage preferred over dc voltage ? Give two reasons.
Two point charges ‘q1’ and ‘q2’ are placed at a distance ‘d’ apart as shown in the figure. The electric field intensity is zero at a point ‘P’ on the line joining them as shown. Write two conclusions that you can draw from this.
In a series LR circuit = R and power factor of the circuit is P₁. When capacitor with capacitance C such that = is put in series, the power factor becomes P₂. Calculate P₁ / P₂.
In the given figure, charge +Q is placed at the centre of a dotted circle. Work done in taking another charge +q from A to B is W₁ and from B to C is W₂. Which one of the following is correct ?
i) W₁ > W₂
(ii) W₁ = W₂
(iii) W₁ < W₂