Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions

Determine the equivalent resistance of networks shown in Fig.

Draw a ray diagram showing the image formation of a distant object by a refracting telescope ?

Write the two important factors considered to increase the magnifying power?

Describe briefly the two main limitations and explain how far these can be minimized in a reflecting telescope ?

"A telescope resolves whereas a microscope magnifies." Justify this statement ?

Describe briefly how the Davisson-Germer experiment demonstrated the wave nature of electrons.

Draw a labelled ray diagram of an astronomical telescope to show the image formation of a distant object. Write the main considerations required in selecting the objective and eyepiece lenses in order to have large magnifying power and high resolution of the telescope.

What does a polaroid consist of? How does it produce a linearly polarised light?

Why photoelectric effect cannot be explained on the basis of wave nature of light? Give reasons.

State Kirchhoff's rules for an electric network. Using Kirchhoff's rules, obtain the balance condition in terms of the resistances of four arms of Wheatstone bridge.

Write two important limitations of a refracting telescope over a reflecting-type telescope.

Unpolarised light is incident on a polaroid. How would the intensity of transmitted light change when the polaroid is rotated?

Define its magnifying power and write the expression for it?

A rectangular loop of wire of size 4 cm × 10 cm carries a steady current of 2 A. A straight long wire carrying 5 A current is kept near the loop as shown. If the loop and the wire are coplanar, find

(i) the torque acting on the loop and

(ii) the magnitude and direction of the force on the loop due to the current carrying wire.

Using Kirchhoff’s rules determine the value of unknown resistance R in the circuit so that no current flows through 4 Ω resistance. Also find the potential difference between A and D.

Define magnifying power of a telescope. Write its expression.

A small telescope has an objective lens of focal length 150 cm and an eye piece of focal length 5 cm. If this telescope is used to view a 100 m high tower 3 km away, find the height of the final image when it is formed 25 cm away from the eye piece.

How is the working of a telescope different from that of a microscope?

The focal lengths of the objective and eyepiece of a microscope are 1.25 cm and 5 cm respectively. Find the position of the object relative to the objective in order to obtain an angular magnification of 30 in normal adjustment.

Draw a simple circuit of a CE transistor amplifier. Explain its working ?