Comprehensive Physics Test-1

Electric field lines:

• Never intersect

• Intersect at acute angles

• Intersect at right angles

• None of these

Answer explanation

Electric field lines represent the direction of the electric field. They never intersect because at any point in space, the electric field has a unique direction. If they did intersect, it would imply two different directions at the same point.

The SI unit of electric field intensity is:

• Newton/Coulomb

• Volt/Meter

• Both (a) and (b)

• None of these

Answer explanation

The electric field intensity can be expressed in two equivalent units: Newton per Coulomb (N/C) and Volt per Meter (V/m). Therefore, the correct answer is both (a) and (b).

Coulomb’s law is valid for:

• Point charges only

• Distributed charges only

• Both point and distributed charges

• None of these

Answer explanation

Coulomb's law describes the force between two point charges. It is not applicable to distributed charges, where the charge is spread over a volume or area. Therefore, the correct answer is 'Point charges only'.

Electric field due to a point charge varies with distance as:

• 1/r

• 1/r^2

• 1/r^3

• None of these

Answer explanation

The electric field (E) due to a point charge (Q) is given by E = kQ/r^2, where k is a constant. This shows that the electric field varies inversely with the square of the distance (r), making the correct answer 1/r^2.

A positive test charge is placed in a uniform electric field. The force on it is:

• Along the field

• Opposite to the field

• Perpendicular to the field

• Zero

Answer explanation

A positive test charge experiences a force in the direction of the electric field. Therefore, the correct answer is 'Along the field', as the force on a positive charge aligns with the direction of the electric field.

The magnitude of the electric field inside a conductor in electrostatic equilibrium is:

• Zero

• Maximum

• Equal to the field outside

• None of these

Answer explanation

In electrostatic equilibrium, charges within a conductor redistribute themselves until the electric field inside is zero. This is because any electric field would cause further movement of charges, contradicting the equilibrium condition.

The potential difference between two points in an electric field is:

• Path-dependent

• Path-independent

• Always zero

• None of these

Answer explanation

The potential difference between two points in an electric field is path-independent, meaning it does not depend on the route taken between the points. This is a fundamental property of conservative electric fields.

Electric dipole moment is defined as:

• Charge × distance

• Distance/charge

• Charge/distance

• None of these

Answer explanation

The electric dipole moment is defined as the product of charge and the distance between the charges. Therefore, the correct choice is 'Charge × distance'.

A point charge is placed at the center of a spherical Gaussian surface. The electric flux through the surface depends on:

• The charge

• The radius of the sphere

• Both charge and radius

• None of these

Answer explanation

The electric flux through a spherical Gaussian surface is determined by Gauss's law, which states that it depends only on the enclosed charge. Therefore, the correct answer is 'The charge', as the radius does not affect the flux.

The electric flux through a closed surface surrounding a charge is proportional to:

• The charge enclosed

• The area of the surface

• The square of the radius

• None of these

Answer explanation

According to Gauss's law, the electric flux through a closed surface is directly proportional to the charge enclosed within that surface. Therefore, the correct answer is 'The charge enclosed'.