ISC (Science) ISC Class 12 - CISCE Important Questions for Physics (Theory)

Identify the part of the electromagnetic spectrum which is suitable for radar system used in aircraft navigation.

Identify the part of the electromagnetic spectrum which is suitable for radar system used in aircraft navigation.

State how a moving coil galvanometer can be converted into an ammeter.

Arrangement of an oxygen ion and two hydrogen ions in a water molecule is shown in figure below.

Calculate electric dipole moment of water molecule. Express your answer in terms of e (charge on hydrogen ion), l and θ.

What happens when an electron collides with a positron?

Draw a labelled circuit diagram of a potentiometer to measure the internal resistance ‘r’ of a cell. Write the working formula (derivation is not required). 

What happens when an electron collides with a positron?

A short electric dipole (which consists of two point charges, +q and -q) is placed at the centre 0 and inside a large cube (ABCDEFGH) of length L, as shown in Figure 1. The electric flux, emanating through the cube is:

a) `q"/"4piin_9L`

b) zero

c) `q"/"2piin_0L`

d) `q"/"3piin_0L`

Derive an expression for the intensity of electric field at a point in broadside position or on [4)
an equatorial line of an electric dipole.

The intensity of the electric field at a perpendicular distance of 0·5 m from an infinitely long line charge having linear charge density (λ) is 3-6 × 10³ Vm^-1. Find the value of λ.

The intensity of the electric field at a point at a perpendicular distance ‘r’ from an infinite line charge, having linear charge density ‘λ’ is given by:

A charged oil drop weighing 1.6 x 10^-15 N is found to remain suspended in a uniform electric field of intensity 2 x 10³ Nc^-1. Find the charge on the drop. 

Two-point charges Q₁ = 400 μC and Q₂ = 100 μC are kept fixed, 60 cm apart in a vacuum. Find the intensity of the electric field at the midpoint of the line joining Q₁ and Q₂.  

In an electric dipole, at which point is the electric potential zero ? 

Show that intensity of electric field at a point in broadside position of an electric dipole is given by:

E = `(1/(4piepsilon_0)) "p"/(("r"^2 + l^2)^(3//2))`

Where the terms have their usual meaning.

In an electric dipole, what is the locus of a point having zero potential?

In case of an infinite line charge, how does intensity of electric field at a point change, if at all, when.

1. charge on it is doubled?
2. distance of the point is halved?

What is meant by the statement: "Relative permittivity of water is 81"?

 A closed surface in vacuum encloses charges –q and +3q. The total electric flux emerging out of the surface is :

State Gauss’Law.