6 + Interview Questions in ELECTRIC POTENTIAL IN GENERAL AWARENESS Page 1 InterviewSolution

1.	Write any two properties of equipotential surface.
Answer» 1. No two equipotential surfaces or planes cut each other because then there would be two values of electric potential at the intersection point, which is not possible. 2. The surface of a conductor is always equipotential. Actually, the whole volume of a conductor is at equal potential. 3. Equipotential surfaces indicate regions of strong or weak electric fields. Using E = \(-\frac{d V}{d r}\) or dr = \(-\frac{d V}{E}\) since dV (i.er potential difference) is constant on the equipotential surface, so dr ∝ \(\frac{1}{E}\) 4. If E is strong, dr will be small and the separation of equipotential surfaces will small than the electric field is strong. The separation between equipotential surface is large than the electric field is weak.

1.

Write any two properties of equipotential surface.

Answer»

1. No two equipotential surfaces or planes cut each other because then there would be two values of electric potential at the intersection point, which is not possible.

2. The surface of a conductor is always equipotential. Actually, the whole volume of a conductor is at equal potential.

3. Equipotential surfaces indicate regions of strong or weak electric fields. Using E = \(-\frac{d V}{d r}\) or dr = \(-\frac{d V}{E}\)
since dV (i.er potential difference) is constant on the equipotential surface, so dr ∝ \(\frac{1}{E}\)

4. If E is strong, dr will be small and the separation of equipotential surfaces will small than the electric field is strong. The separation between equipotential surface is large than the electric field is weak.

Discussion

2.	The electric potential at the surface of a charged conducting hollow sphere of radius 2 m is 500 volt. The potential at the distance of 1.5 m from the centre is:(a) 375 V(b) 250 V(c) zero(d) 500V
Answer» (d) 500V Electric potential inside and on surface of charged conducting sphere will be same. Electric potential inside the hollow spherical conductor is equal to the potential at the surface of the conductor. ∴ V = 500 Volt

Discussion

3.	The kinetic energy of a α-particle to move from the points where potential have 70 V to 50 V from rest is:(a) 20 eV(b) 40 eV(c) 20 MeV(d) 40 MeV
Answer» (b) 40 eV Work done W = qV W = (2e)[V_B – V_A] = (2e) [20] volt or W = 40 eV

Discussion

4.	A unit charge is rotated around a charge of q in a circular path at the distance of r. Then, work done will be:(a) zero(b) \(\frac{1}{4 \pi \varepsilon_{0}} \frac{q}{r^{2}} J\)(c) 2 πr J(d) 2πrq J
Answer» (a) zero Circular path will act like a equipotential surface. So work done in moving unit charge will be zero.

Discussion

5.	How much work is done in taking an electron between two points that have potential difference of 20 V?
Answer» W = q₀V = 1.6 × 10^-19 × 20 = 32 × 10^-19 J

Discussion

6.	Why is static electric potential of the whole volume of the charged conductor equivalent to that on its surface?
Answer» Electric field inside whole volume of charged conductor is zero. ∵ E = \(-\frac{d V}{d r}\) E = 0 ⇒ V = constant (Electric potential is uniform in whole volume) Inside conductor the work done in bringing any test charge from inside point to surface will be zero. W = q₀(V_B – V_A) V_B – V_A = 0 ∴ V_A = V_B Potential of both points will be equal.

Discussion

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Write any two properties of equipotential surface.

The electric potential at the surface of a charged conducting hollow sphere of radius 2 m is 500 volt. The potential at the distance of 1.5 m from the centre is:(a) 375 V(b) 250 V(c) zero(d) 500V

The kinetic energy of a α-particle to move from the points where potential have 70 V to 50 V from rest is:(a) 20 eV(b) 40 eV(c) 20 MeV(d) 40 MeV

A unit charge is rotated around a charge of q in a circular path at the distance of r. Then, work done will be:(a) zero(b) \(\frac{1}{4 \pi \varepsilon_{0}} \frac{q}{r^{2}} J\)(c) 2 πr J(d) 2πrq J

How much work is done in taking an electron between two points that have potential difference of 20 V?

Why is static electric potential of the whole volume of the charged conductor equivalent to that on its surface?