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

Define the term wavefront. Using Huygen’s wave theory, verify the law of reflection. 

Answer the following question.
Three photodiodes D1, D2, and D3 are made of semiconductors having band gaps of 2.5 eV, 2 eV, and 3 eV respectively. Which of them will not be able to detect light of wavelength 600 nm? 

Answer the following question.
Under what conditions is the phenomenon of total internal reflection of light observed? Obtain the relation between the critical angle of incidence and the refractive index of the medium.

Answer the following question.
Three lenses of focal length +10 cm, —10 cm and +30 cm are arranged coaxially as in the figure given below. Find the position of the final image formed by the combination. 

Answer the following question.
Define the term "Threshold frequency", in the context of photoelectric emission.

Answer the following question.
A charged particle q is moving in the presence of a magnetic field B which is inclined to an angle 30° with the direction of the motion of the particle. Draw the trajectory followed by the particle in the presence of the field and explain how the particle describes this path.

Answer the following question.
Explain briefly how Rutherford scattering of α-particle by a target nucleus can provide information on the size of the nucleus.

Answer the following question.
Define the term wavefront. Using Huygen's wave theory, verify the law of reflection.

The work function of aluminum is 4⋅2 eV. If two photons each of energy 2⋅5 eV are incident on its surface, will the emission of electrons take place? Justify your answer.

Define a wavefront. Using 'Huygens' principle, draw the shape of a refracted wavefront, when a plane wave is incident on a convex lens.

A plane wave front AB propagating from denser medium (1) into a rarer medium (2) is incident on the surface P₁P₂ separating the two media as shown in fig.

Using Huygen’s principle, draw the secondary wavelets and obtain the refracted wave front in the diagram.

With the help of a ray diagram, obtain the relation between its focal length and radius of curvature.

Without the concept of displacement current it is not possible to correctly apply Ampere’s law on a path parallel to the plates of parallel plate capacitor having capacitance C in ______.

Displacement current is given by ______.

In an a.c. circuit, with phase voltage V and current I, the power dissipated is ______.

According to Cartesian sign convention, all distances are measured from the _______.

Focal length of a mirror is given by ______.

According to the mirror equation, ______.

According to Huygens principle, ______.

According to Huygen's construction, relation between old and new wavefront is ______.