# IIT JEE Advanced & Mains Physics 2018 : Electricity : Rankfile / expected questions IV

IIT JEE Advanced & Mains Physics 2018 : Electricity : Rank file / expected questions / Physicsmynd Elite Series  /  Page  IV

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28 ] A  spherically symmetrical charge distribution has density

Then the energy stored in region r < R is –

A ]

B ]

C ]

D ]

29 ] Two point charges of equal masses and charges  m and  Q respectively are suspended at a common point by two threads of negligible mass and length l .If at equilibrium, the angle of inclination of each thread to the vertical is   , then   is proportional to –

A ]

B ]

C ]

D ]

30 ] In the above arrangement , if   is very small , then  is given by –

A ]

B ]

C ]

D ]

31 ] Consider two conducting planes kept at a particular angle to each other in the xy axis with the point of contact being at the origin . Obviously . work must be done to bring a point charge to the region of contact between the planes. Then , finding the work done ,using the method of images [in the above case ] is  possible if the angle is [ in degrees] –

A ] 20

B ] 30

C ] 40

D ] 50

32 ] The issue with the angle in the above case is due to the fact that there is –

A ] Difficulty in finding the location of the image charge.

B ] Difficulty in finding the location of the equipotential.

C ] Difficulty in finding the location of the charge at infinity .

D ] A and B

E ] A , B and C

33 ] A charge q is kept in a pyramid ,on the center of it’s base ,which is square shaped . Then the flux through any face of the pyramid is –

A  ] zero

B ]

C ]

D ]

34 ]  A hollow cylinder of resistivity  has length L .It’s  inner radius is a and outer radius b  . Then the resistance produced when a  potential difference is generated between the ends of the cylinder is –

A]

B ]

C ]

D ]

35 ] In the above case –

A ] No current flows through the cylinder .

B ] Current flows parallel to the axis of the cylinder.

C ] Current flows radially outward from the axis of the cylinder

D ] Current flows perpendicular to the axis of the cylinder

36 ] Continuing with question no .34 , what if  the potential difference is applied between the inner and outer surfaces of the cylinder ? [ Choose the right combination ]

a ) Current flows parallel to the axis of the cylinder.

b ) Current flows radially outward from the axis of the cylinder

c ) Resistance remains the same .

d ) Resistance becomes

e ) Resistance becomes

f )  No current flows through the cylinder