Two isolated conducting spheres of radii 2 cm and 6 cm are charged and then connected by a long thin wire. The ratio of the surface charge density of the smaller sphere to that of the larger sphere becomes:

A
1 : 3
B
9 : 1
C
1 : 9
D
3 : 1

Q107. AI-generated practice Single-correct MCQ Medium

A point charge +q is placed inside the cavity of an uncharged hollow conductor without touching it. The charges induced on the inner and outer surfaces of the conductor are respectively:

A
+q and −q
B
−q and zero
C
zero and +q
D
−q and +q

Q108. AI-generated practice Single-correct MCQ Medium

Lightning conductors are given sharp pointed ends because:

A
the electric field is zero near sharp points
B
charge density is smallest at sharp points
C
charge density and electric field are largest at sharp points
D
sharp points have the highest potential on the conductor

Q109. AI-generated practice Single-correct MCQ Hard

A conducting sphere of radius 10 cm is at a potential of 900 V. Take 1/(4πε₀) = 9 × 10⁹ N m² C^-2. The charge on it is:

A1 × 10^-6 C
B1 × 10^-8 C
C9 × 10^-8 C
D1 × 10^-10 C

Q110. AI-generated practice Single-correct MCQ Medium

In a uniform electric field, the equipotential surfaces for equal steps of potential are:

A
equally spaced planes perpendicular to the field
B
planes whose spacing increases along the field
C
concentric spheres
D
equally spaced planes parallel to the field

Q111. AI-generated practice Single-correct MCQ Hard

Two concentric thin conducting shells have radii a and b (b greater than a) and carry charges q and Q respectively. The potential of the inner shell is (k = 1/4πε₀):

A
kq/a
B
k(q + Q)/b
C
k(q + Q)/a
D
k(q/a + Q/b)

Q112. AI-generated practice Single-correct MCQ Easy

During a thunderstorm, the safest place to stay among the following is:

A
inside a car with a metal body
B
under a tall isolated tree
C
in an open field
D
on top of a hill

Q113. AI-generated practice Single-correct MCQ Medium

Equipotential surfaces of 10 V, 20 V and 30 V are parallel planes 5 cm apart in a uniform field. The magnitude of the field is:

A
50 V/m
B
100 V/m
C
2 V/m
D
200 V/m

Q114. AI-generated practice Single-correct MCQ Hard

A conducting sphere of radius R carries charge Q. The ratio of the field just outside its surface to the field at a distance 2R from its centre is:

A
1 : 4
B
4 : 1
C
2 : 1
D
1 : 1

Q115. AI-generated practice Numerical value Easy

A conducting sphere of radius 20 cm carries a charge of 4 nC. Take 1/(4πε₀) = 9 × 10⁹ N m² C^-2. Find the potential (in volt) at its centre.

Q116. AI-generated practice Numerical value Medium

Two isolated conducting spheres of radii 3 cm and 6 cm have a total charge of 15 nC between them. They are connected by a thin wire. Find the final charge (in nC) on the smaller sphere.

Q117. AI-generated practice Numerical value Medium

A uniform electric field of 300 V/m exists in a region. Find the potential difference (in volt) between two equipotential planes 4 cm apart.

Q118. AI-generated practice Numerical value Hard

A hollow conducting sphere of radius 12 cm carries a charge of 4 nC. Take 1/(4πε₀) = 9 × 10⁹ N m² C^-2. Find the potential (in volt) at a point 5 cm from its centre.

Q119. AI-generated practice Assertion–Reason Easy

Assertion (A): The surface of a charged conductor in electrostatic equilibrium is an equipotential surface.
Reason (R): The electric field just outside a charged conductor is perpendicular to its surface.

A
Both A and R are true and R is the correct explanation of A
B
Both A and R are true but R is not the correct explanation of A
C
A is true but R is false
D
A is false but R is true

Q120. AI-generated practice Assertion–Reason Medium

Assertion (A): The electric field inside the cavity of a hollow conductor is always zero.
Reason (R): In electrostatic equilibrium, the net charge of a conductor resides on its outer surface.

A
Both A and R are true and R is the correct explanation of A
B
Both A and R are true but R is not the correct explanation of A
C
A is true but R is false
D
A is false but R is true