Science (English Medium) Class 12 - CBSE Question Bank Solutions for Physics

Write any two factors which justify the need for modulating a signal ?

Draw a diagram showing an amplitude modulated wave by superposing a modulating signal over a sinusoidal carrier wave.

Explain, giving reasons, the basic difference in converting a galvanometer into (i) a voltmeter and (ii) an ammeter?

How does focal length of a lens change when red light incident on it is replaced by violet light? Give reason for your answer.

Define dipole moment of an electric dipole. Is it a scalar or a vector?

Draw a labelled diagram of a moving coil galvanometer and explain its working. What is the function of radial magnetic field inside the coil?

Define power of a lens. Write its units. Deduce the relation `1/f =1/f_1  +1/f_2`for two thin lenses kept in contact coaxially.

Define electric dipole moment. 

In the meter bridge experiment, balance point was observed at J with AJ = l.

(i) The values of R and X were doubled and then interchanged. What would be the new position of balance point?

(ii) If the galvanometer and battery are interchanged at the balance position, how will the alance point get affected?

Write briefly any two factors which demonstrate the need for modulating a signal. Draw a suitable diagram to show amplitude modulation using a sinusoidal signal as the modulating signal.

State the principle of the working of a moving coil galvanometer, giving its labeled diagram ?

Outline the necessary steps to convert a galvanometer of resistance RG into an ammeter of a given range ?

In which orientation, a dipole placed in a uniform electric field is in (i) stable, (ii) unstable equilibrium?

Find the radius of curvature of the convex surface of a plano-convex lens, whose focal length is 0.3 m and the refractive index of the material of the lens is 1.5.

State the underlying principle of working of a moving coil galvanometer. Write two reasons why a galvanometer can not be used as such to measure current in a given circuit. Name any two factors on which the current sensitivity of a galvanometer depends.

A normal eye is not able to see objects closer than 25 cm because

A thin converging lens is formed with one surface convex and the other plane. Does the position of image depend on whether the convex surface or the plane surface faces the object?

A double convex lens has two surfaces of equal radii R and refractive index \[m = 1 \cdot 5\]

A symmetric double convex lens in cut in two equal parts by a plane perpendicular to the principal axis. If the power of the original lens was 4 D, the power a cut-lens will be

A symmetric double convex lens is cut in two equal parts by a plane containing the principal axis. If the power of the original lens was 4 D, the power of a divided lens will be