Electrostatic Potential and Capacitance · Question 61

A parallel plate air capacitor is charged to a potential difference of V volts. After disconnecting the charging battery the distance between the plates of the capacitor is increased using an insulating handle. As a result the potential difference between the plates

1. increases
2. decreases
3. does not change
4. becomes zero

An electric dipole of moment p is lying along a uniform electric field E. The work done in rotating the dipole by 90 is

1. pE
2. 2pE
3. pE/2
4. 2pE

A network of four capacitors of capacity equal to C1 = C, C2 = 2C, C3 = 3C and C4 = 4C are connected to a battery as shown in the figure. The ratio of the charges on C2 and C4 is [figure]

1. 4/7
2. 3/22
3. 7/4
4. 22/3

As per the diagram a point charge +q is placed at the origin O. Work done in taking another point charge −Q from the point A [coordinates (0, a)] to another point B [coordinates (a, 0)] along the straight path AB is [figure]

1. zero
2. ( qQ4 0 1a2 ) 2a
3. ( -qQ4 0 1a2 ) 2a
4. ( qQ4 0 1a2 ) a 2

Two charges q1 and q2 are placed 30 cm apart, as shown in the figure. A third charge q3 is moved along the arc of a circle of radius 40 cm from C to D. The change in the potential energy of the system is q34 0k, where k is [figure]

1. 8q1
2. 6q1
3. 8q2
4. 6q2

A bullet of mass 2 g is having a charge of 2 C. Through what potential difference must it be accelerated, starting from rest, to acquire a speed of 10 m/s ?

1. 5 kV
2. 50 kV
3. 5 V
4. 50 V

An electric dipole has the magnitude of its charge as q and its dipole moment is p. It is placed in a uniform electric field E. If its dipole moment is along the direction of the field, the force on it and its potential energy are respectively

1. 2q.E and minimum
2. q.E and p.E
3. zero and minimum
4. q.E and maximum

Three capacitors each of capacity 4 are to be connected in such a way that the effective capacitance is 6 . This can be done by

1. connecting all of them in series
2. connecting them in parallel
3. connecting two in series and one in parallel
4. connecting two in parallel and one in series

Identical charges (-q) are placed at each corner of a cube of side b then electrostatic potential energy of charge (+q) which is placed at centre of cube will be

1. -4 2q2 0 b
2. -8 2q2 0 b
3. -4q2 3 0 b
4. 8 2q24 0 b

Some charge is being given to a conductor. Then its potential is

1. maximum at surface
2. maximum at centre
3. remains same throughout the conductor
4. maximum somewhere between surface and centre.