Electrostatics (KVPY Stream SB-SX (Class 12 & 1st Year BSC) Physics): Questions 3 - 5 of 13

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Question number: 3

» Electrostatics » Forces Between Multiple Charges

Appeared in Year: 2010

MCQ▾

Question

Three equal charges + q are placed at the three vertices of an equilateral triangle centered at the origin. They are held in equilibrium by a restoring force of magnitude F (r) = Kr directed towards the origin, where k is a constant. What is the distance of the three charges from the origin?

Choices

Choice (4) Response

a.

[34πε0q2K]23

b.

[16πε0q2K]12

c.

[16πε0q2K]23

d.

[312πε0q2K]13

Question number: 4

» Electrostatics » Capacitors

Appeared in Year: 2012

MCQ▾

Question

The capacitor of capacitance C in the circuit shown is fully charged initially, Resistance is R.

Circuit diagram of resistance and capacitor

Circuit Diagram of Resistance and Capacitor

In figure RC circuit diagram is shown.

After the switch S is closed, the time taken to reduce the stored energy in the capacitor to half its initial value is:

Choices

Choice (4) Response

a.

Cln 2

b.

2RCln2

c.

RCln22

d.

RC2

Question number: 5

» Electrostatics » Forces Between Two Point Charges

Appeared in Year: 2013

MCQ▾

Question

Consider an initially neutral hollow conducting spherical shell with inner radius r and outer radius 2r. A point charge + Q is now placed inside the shell at a distance r2 from the centre. The shell is then grounded by connecting the outer surface to the earth. P is an external point at a distance 2r from the point charge + Q on the line passing through the centre and the point charge + Q as shown in the figure.

A hollow conducting spherical shell

A Hollow Conducting Spherical Shell

Figure shows, a hollow conducting spherical shell with inner radius r and outer radius 2r. A point charge + Q is placed inside the shell at a distance r/2 from center and P is an external point at distance 2r from the point charge + Q.

The magnitude of the force on a test charge + q placed at P will be –

Choices

Choice (4) Response

a.

14πε04qQ25r2

b.

14πε0qQ4r2

c.

0

d.

14πε09qQ100r2

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