MODEL PAPER 6 Physics - MODEL PAPER 6

The diode used in the circuit shown in the figure has a constant voltage drop at 0.5 V at all currents and a maximum power rating of 100 milliwatts. What should be the value of the resistor R, connected in series with diode for obtaining maximum current?

A vertical straight conductor carries a current vertically upwards. A point P lies to the east of it at a small distance and another point Q lies to the west in the same direction. The magnetic field at P is:

The ratio of magnetic fields due to a small bar magnet in the end on position to the broad side on position is

The layered lens is made of two kinds of glass. A point source of light is placed on its principal axis. If the reflections from the boundaries between layers are ignored, the lens will form

Assertion (A): Transformers are used only in alternating current sources, not in direct current.
Reasons (R): Only a.c. can be stepped up or down by means of transformers.

Assertion (A): Skiers use air glasses.
Reason (R): Light reflected by snow is partially polarised.

Assertion: Two concentric charged inner and outer shell are given. The potential difference between the shells depends on charge of inner shell.
Reason: Potential due to charge of outer shell remains same at every point inside the sphere.

Assertion (A): The de Broglie wavelength of a molecule varies inversely as the square root of temperature.
Reason (R): The root mean square velocity of the molecule depends on the temperature.

What will be the path of a charged particle moving in a region of crossed (or transverse) uniform electrostatic and magnetic fields with initial velocity zero?

The ground state energy of hydrogen atom is -13.6 eV. If an electron makes a transition from an energy level-1.51 eV to - 3.4 eV, then calculate the wavelength of the spectral line emitted and name the series of hydrogen spectrum to which it belongs.

Two magnetic poles, one of which is 10 times as strong as the other, exert on each other a force equal to 9.604 mN , when placed 10 cm apart in air. Find the strength of the two poles.

Two cells of emf 2E and E and internal resistances 2r and r respectively, are connected in parallel. Obtain the expressions for the equivalent emf and the internal resistance of the combination.

i. Define mutual inductance.
ii. A pair of adjacent coils has a mutual inductance of 1.5 H. If the current in one coil changes from 0 to 20 A in 0.5 s, what is the change of flux linkage with the other coil?

With the help of a diagram, explain the principle of a device which changes a low voltage into a high voltage but does not violate the law of conservation of energy. Give any one reason why the device may not be 100% efficient.

a. Explain why, for any charge configuration, the equipotential surface through a point is normal to the electric field at that point.
Draw a sketch of equipotential surfaces due to a single charge (-q), depicting the electric field lines due to the charge.
b. Obtain an expression for the work done to dissociate the system of three charges placed at the vertices of an equilateral triangle of side a as shown alongside.