# CBSE Delhi-Set-2-2004

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• Q1

Which physical quantity has the unit Wb/m2? Is it a scalar or vector quantity?

Marks:1

It is the SI unit of magnetic field B. Magnetic field is vector quantity.

• Q2

In the diagram below is shown a circular loop carrying crurent I. Show the direction of the magnetic field with the help of lines of force.

Marks:1

The direction of magnetic field is shown in figure below,

• Q3

Name the type of modulation scheme preferred for digital communication.

Marks:1

The type of modulation scheme preferred for digital communication is pulse code modulation (PCM).

• Q4

What is the name given to that part of electromagnetic spectrum which is used for taking photographs of earth under foggy conditions from great heights?

Marks:1

Infrared rays.

• Q5

What is the name given to that part of the electromagnetic spectrum which is used in ‘Radar’?

Marks:1

• Q6

Find the wavelength of electromagnetic waves of frequency 5 x 1019Hz in free space. Give its two applications.

Marks:2

The wavelength for the given frequency is given by the relation,

= c/v

= (3108)/(51019

=( 610-12)m

= 0.006 Ao

This wavelength of light falls into X-rays region, which can be used for,

(i) The treatment of certain diseases.

(ii) Diagnosis of diseases.

• Q7

Draw a circuit diagram to show how a photo-diode is biased. Draw its characteristic curves for two different illumination intensities.

Marks:2

A photodiode is always used under reverse biased condition. The circuit diagram for the same is as shown in figure below,

• Q8

Draw the graph showing the variation of binding energy per nucleon with mass number. Give reason for the decrease of binding energy per nucleon for nuclei with high mass numbers.

Marks:2

The graph showing the variation of binding energy per nucleon with mass number of different atomic nuclei is given below,

The binding energy per nucleon for nuclei with high mass numbers is low because there is large coulomb replusion between the protons inside the nuclei.

• Q9

Draw the graph showing the variation of binding energy per nucleon with mass number. Give the reason for the decrease of binding energy per nucleon for nuclei with high mass numbers.

Marks:2

The graph showing the variation of binding energy per nucleon with mass number of different atomic nuclei is given below,

As the mass number increases the binding energy decreases, as there is large coulomb repulsion between the protons inside these nuclei.

• Q10

With the help of a diagram, show the biasing of a light emitting diode (LED). Give its two advantages over conventional incandescent lamps.

Marks:2