# CBSE Delhi-Set-1-2006

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• Q1

Define the term ‘dielectric constant’ of a medium in terms of capacitance of a capacitor.

Marks:1

The ratio of capacitance of a capacitor with given dielectric medium to the capacitance of same capacitor with free space in between the plates is called dielectric constant of medium.

• Q2

Sketch a graph showing variation of resistivity of carbon with temperature.

Marks:1

The required graph is given below:

• Q3

The vertical component of Earth’s magnetic field at a place is 3 times the horizontal component. What is the value of angle of dip at this place?

Marks:1

According to given condition,

Angle of dip is given by the formula,

• Q4

With what purpose was famous Davisson-Germer experiment with electrons performed?

Marks:1

It was performed to demonstrate the wave nature of electrons and to measure the de Broglie wavelength of electron waves.

• Q5

Name the type of communication in which the signal is a discrete and binary coded version of the message or information.

Marks:1

In digital communication the signal is discrete and binary coded.

• Q6

The electric field and electric potential at any point due to a point charge kept in air is 20 NC-1 and 10 JC-1 respectively. Compute the magnitude of this charge.

Marks:2

• Q7

Write the mathematical relation between mobility and drift velocity of charge carriers in a conductor. Name the mobile charge carriers responsible for conduction of electric current in (i) an electrolyte (ii) an ionised gas.

Marks:2

The mathematical relation between mobility and drift velocity of carge carriers in a conductor is given by

where Vd = Drift speed and E= Applied electric field.

The mobile charge carriers responsible for conduction of electric current are:
(i) Electrolyte:- Positively charge carriers(cations) and negatively charge carriers(anions).
(ii)Ionised gas:- Positively charged gas ions and electrons.

• Q8

State the principle of working of a cyclotron. Write two uses of this machine.

Marks:2

The working principle of cyclotron is given as follows:-
1. An ion beam when moving perpendicular to a uniform magnetic field describes a circular path and time for one revolution is independent of the velocity of ions as well as radius of circular path.
2. An ion beam can be accelerated to a high energy by applying suitable electrical potentials in a suitable manner.
The two uses of cyclotron are given as follows:-
1. For the production of highly energetic ions.
2. In implantation of ions into solids so that their properties can be changed.

• Q9

Draw a labelled ray diagram of a reflecting type telescope. Write its any one advantage over refracting type telescope.

Marks:2

The labeled diagram of a reflecting type telescope is given below:

The main advantage of reflecting type telescope over refracting telescope is that it completely removes the chromatic aberrations in the image formed.

• Q10

Draw and explain the output waveform across the load resistor R, if the input waveform is as shown in the given figure.

Marks:2