MODEL PAPER 10 Physics - MODEL PAPER 10

What happens to fringe width in the Young's double slit experiment, if it is performed in glycerine instead of air?

A Rowland ring of mean radius 15 cm has 3500 turns of wire wound on a ferromagnetic core of relative permeability 800. What is the magnetic field B in the core for a magnetising current of 1.2A?

Consider the junction diode as ideal. The value of current flowing through AB is 

In electrolytic capacitors positive terminal is

Assertion (A): The photoelectrons produced by a monochromatic light beam incident on a metal surface have a spread in their kinetic energies.
Reason (R): The energy of electrons emitted from inside the metal surface, is lost in collision with the other atoms in the metal.

Assertion (A): Positive charge always moves from a higher potential point to a lower potential point. 
Reason (R): Electric potential is a vector quantity.

Assertion (A):  An alternating current of frequency 50 Hz becomes zero, 100 times in one second. 
Reason (R): Alternating current changes direction and becomes zero twice in a cycle.

Depict the field-line pattern due to a current-carrying solenoid of finite length.
i. In what way do these lines differ from those due to an electric dipole?
ii. Why can't two magnetic field lines intersect each other?

Draw the energy band diagram of (i) n-type, and (ii) p-type semiconductors at temperature T > 0 K. In the case of n-type Si-semiconductor, the donor energy level is slightly below the bottom of conduction band whereas in p-type semiconductor, the acceptor energy level is slightly above the top of valence band. Explain, giving examples, what role do these energy levels play in conduction and valence bands.

Gamma rays and radio waves travel with the same velocity in free space. Distinguish between them in terms of their origin and the main application.

The figure shows two identical rectangular loops (1) and (2) placed on a table along with a straight long current carrying conductor between them.
i. What will be the directions of the induced current in the loops when they are pulled away from the conductor with same velocity v?
ii. Will the emf induced in the two loops be equal?

A rectangular coil P is moved from a point A to another point B with uniform velocity 'v' through a region of a uniform magnetic field acting normally inwards as shown in the figure. Show graphically (i) the variation of magnetic flux associated with the coil with time, (ii) the variation of induced emf across points X and Y of the coil with time. 


Explain the nature of variation in magnetic flux as represented by the graph in the first case.

How is the spacing between fringes in a double slit experiment affected if:
a. the slits separation is increased,
b. the colour of light used is changed from red to blue,
c. the whole apparatus is submerged in a oil of refractive index 1.2?
Justify your anwer in each case.

a. Derive an expression for the impedance of a series L-C-R circuit connected to an AC supply of variable frequency.
b. Explain briefly how the phenomenon of resonance in the circuit can be used in the tuning mechanism of a radio or a TV set?

i. Derive lens maker’s formula for a biconvex lens.
ii. A point object is placed at a distance of 12 cm on the principal axis of a convex lens of focal length 10 cm. A convex mirror is placed coaxially on the other side of the lens at a distance of 10 cm. If the final image coincides with the object, sketch the ray diagram, and find the focal length of the convex mirror.

A series L-C-R circuit is connected to an AC source. Using the phasor diagram, derive the expression for the impedance of the circuit. Plot a graph to show the variation of current with frequency of the source, explaining the nature of its variation.

Find the expression for the energy stored in the capacitor. Also find the energy lost when the charged capacitor is disconnected from the source and connected in parallel with the uncharged capacitor. Where does this loss of energy appear?