Date & Time: 4th March 2016, 2:00 pm

Duration: 3h

In Figure 1 below, a charge Q is fixed. Another charge q is moved along a circular arc MN of radius r around it, from the point M to the point N such that the length of the arc MN = l. The work done in this process is:

figure 1

zero

`1/(4piε_0).(Qq)/r^2l`

`(Qq)/(2ε_0r^2)l`

`(Qq)/(2piε_0r^2)`

Chapter: [1.01] Electric Charges and Fields

A carbon resistor has coloured bands as shown in Figure 2 below. The resistance of the resistor is:

figure 2

260 ± 10%

260 ± 5%

2600 ± 5%

2600 ± 10%

Chapter: [2] Current Electricity

A solenoid L and a resistor R are connected in series to a battery, through a switch. When the switch is put on, current I flowing through it varies with time t as shown in which of the graphs given below:

Chapter: [2] Current Electricity

Two thin lenses having optical powers of -10D and+ 6D are placed in contact with each other. The focal length of the combination is:

+ 0·25 cm

- 0·25 cm

+ 0·25 m

- 0·25 m

Chapter: [6.01] Ray Optics and Optical Instruments

The total energy of an electron in the ground state of the hydrogen atom is -13·6 eV. Its total energy, when a hydrogen atom is in the first excited state, is:

+ 13·6 eV

+ 3·4 eV

- 3·4 eV

- 54·4 eV

Chapter: [8.01] Atoms

A charged oil drop weighing 1.6 x 10^{-15} N is found to remain suspended in a uniform electric field of intensity 2 x 10^{3} Nc^{-1}. Find the charge on the drop.

Chapter: [1.01] Electric Charges and Fields

For a metallic conductor, what is the relation between current density (J), conductivity (a) and electric field intensity E?

Chapter: [2] Current Electricity

In Figure 3 given below, find the value of resistance x for which points A and B are at the same potential:

figure 3

Chapter: [2] Current Electricity

Write the expression for the Lorentz force F in vector form.

Chapter: [3.01] Moving Charges and Magnetism [3.02] Magnetism and Matter

A coil has a self-inductance of 0·05 Henry. Find the magnitude of the emf induced in it when the current flowing through it is changing at the rate of 100 As^{-1}.

Chapter: [4.01] Electromagnetic Induction

To which regions of the electromagnetic spectrum do the following wavelengths belong:

(a) 250 nm

(b) 1500 nm

Chapter: [5] Electromagnetic Waves

What is the difference between polarised light and unpolarised light?

Chapter: [6.02] Wave Optics

Name the principle on the basis of which optical fibres work.

Chapter: [6.01] Ray Optics and Optical Instruments

Calculate dispersive power of a transparent material given : n_{v} = 1.56, n_{r} = 1.54, n_{y} = 1.55.

Chapter: [6.01] Ray Optics and Optical Instruments

What is meant by short-sightedness ?

Chapter: [6.01] Ray Optics and Optical Instruments

Two metals A and B have work functions 4 eV and 6 eV respectively. Which metal has a lower threshold wavelength for photoelectric effect?

Chapter: [7] Dual Nature of Radiation and Matter

Calculate angular momentum of an electron in the third Bohr orbit of a hydrogen atom.

Chapter: [8.01] Atoms

In a nuclear reactor, what is the function of a moderator?

Chapter: [8.02] Nuclei

In our Nature, where is the nuclear fusion reaction taking place continuously?

Chapter: [8.02] Nuclei

What is the use of Zener diode?

Chapter: [9] Electronic Devices

Two-point charges Q_{1} = 400 μC and Q_{2} = 100 μC are kept fixed, 60 cm apart in a vacuum. Find the intensity of the electric field at the midpoint of the line joining Q_{1} and Q_{2}.

Chapter: [1.01] Electric Charges and Fields

State Gauss’Law.

Chapter: [1.01] Electric Charges and Fields

In an electric dipole, at which point is the electric potential zero ?

Chapter: [1.01] Electric Charges and Fields

Obtain an expression for equivalent capacitance when three capacitors C_{1}, C_{2} and C_{3} are connected in series.

Chapter: [1.02] Electrostatic Potential, Potential Energy and Capacitance

A metallic wire has a resistance of 3.0 Ω at 0°C and 4.8 Ω at 150°C. Find the temperature coefficient of resistance of its material.

Chapter: [2] Current Electricity

In the circuit shown in the figure below, E_{1} and E_{2} are two cells having emfs 2 V and 3 V respectively, and negligible internal resistance. Applying Kirchhoff’s laws of electrical networks, find the values of currents l_{1} and I_{2}.

Chapter: [2] Current Electricity

State how a moving coil galvanometer can be converted into an ammeter.

Chapter: [3.01] Moving Charges and Magnetism

Draw a labelled circuit diagram of a potentiometer to measure the internal resistance ‘r’ of a cell. Write the working formula (derivation is not required).

Chapter: [2] Current Electricity

Define Curie temperature.

Chapter: [3.02] Magnetism and Matter

If magnetic susceptibility of a certain magnetic material is 0 0001, find its relative permeability.

Chapter: [3.02] Magnetism and Matter

Two infinitely long current carrying conductors X and Y are kept parallel to each other, 24 cm apart in a vacuum. They carry currents of 5A and 7A respectively, in the same direction, as shown in the figure below. Find the position of a neutral point, i.e., a point where resultant magnetic flux density is zero. (Ignore earth’s magnetic field).

Chapter: [3.01] Moving Charges and Magnetism

If current through the conductor Y is reversed in direction, will neutral point lie between X and Y, to the left of X or to the right of Y ?

Chapter: [9] Electronic Devices

Define Ampere in terms of force between two current carrying conductors.

Chapter: [3.01] Moving Charges and Magnetism

What is the ideal transformer?

Chapter: [4.02] Alternating Current

A coil having self-inductance of 0.7 H and resistance of 165 Ω is connected to an a.c. source of

275V,50Hz. If π = `22/7`

Calculate:

(i) Reactance of the coil

(ii) Impedance of the coil ‘

(iii) Current flowing through the coil

Chapter: [4.02] Alternating Current

Draw a labelled graph showing a variation of impedance of a series LCR circuit with frequency of the a.c. supply.

Chapter: [4.02] Alternating Current

Derive Snell’s law of refraction using Huygens’s wave theory.

Chapter: [6.01] Ray Optics and Optical Instruments

Monochromatic light of wavelength 650 nm falls normally on a slit of width 1.3 x 10^{-4} cm and the resulting Fraunhofer diffraction is obtained on a screen. Find the angular width of the . central maxima.

Chapter: [6.02] Wave Optics

In Young’s double-slit experiment, show that:

`beta = (lambda "D")/"d"` where the terms have their usual meaning.

Chapter: [6.02] Wave Optics

A ray of ordinary light is travelling in air. It is incident on air glass pair at a polarising angle of 56°. Find the angle of refraction in glass.

Chapter: [6.02] Wave Optics

Find the angle of incidence at which a ray of monochromatic light should be incident on the first surface AB of a regular glass prism ABC so that the emergent ray grazes the adjacent surface AC. (Refractive Index of glass = 1 .56)

Chapter: [6.02] Wave Optics

State how the focal length of a glass lens (Refractive Index 1.5) changes when it is completely immersed in:

(i) Water (Refractive Index 1.33)

(ii) A liquid (Refractive Index 1.65)

Chapter: [6.01] Ray Optics and Optical Instruments

A convex lens of a focal length 5 cm is used as a simple microscope. Where should an object be placed so that the image formed by it lies at the least distance of distinct vision (D = 25 cm)?

Chapter: [6.01] Ray Optics and Optical Instruments

Draw a labelled ray diagram showing the formation of an image by a refracting telescope when the final image lies at infinity.

Chapter: [6.01] Ray Optics and Optical Instruments

Monochromatic fight of wavelength 198 nm is incident on the surface of a metallic cathode whose work function is 2.5 eV How much potential difference must be applied between the cathode and the anode of a photocell to just stop the photocurrent from flowing?

Chapter: [6.02] Wave Optics

State de Broglie hypothesis

Chapter: [7] Dual Nature of Radiation and Matter

What conclusion can be drawn from Davisson and Germer’s experiment ?

Chapter: [7] Dual Nature of Radiation and Matter

How are various lines of Lyman series formed? Explain on the basis of Bohr’s theory.

Chapter: [8.01] Atoms

Calculate the shortest wavelength of electromagnetic radiation present in Balmer series of hydrogen spectrum.

Chapter: [5] Electromagnetic Waves

State the effect of the following changes on the X-rays emitted by Coolidge X-ray tube :

(i) High voltage between cathode and anode is increased.

(ii) Filament temperature is increased.

Chapter: [7] Dual Nature of Radiation and Matter

Half-life of a certain radioactive material is 8 hours.

Find the disintegration constant of this material.

Chapter: [8.02] Nuclei

Half life of a certain radioactive material is 8 hours.

If one starts with 600 g of this substance, how much of it will disintegrate in one day?

Chapter: [8.02] Nuclei

Sketch a graph showing the variation of binding energy per nucleon of a nucleus with its mass number.

Chapter: [8.02] Nuclei

Draw a circuit diagram for the common emitter transistor amplifier. What is meant by phase reversal?

Chapter: [9] Electronic Devices

Write the truth table of the following circuit. Name the gate represented by this circuit.

Chapter: [9] Electronic Devices

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