CBSE Physics  Sample Paper 1998 
(Outside Delhi) Part - 1

 

Q. 1. Give the ratio of velocity of light rays of wavelength 4,000 A and 8,000 A in vacuum. 1

 

Q. 2. A student obtains resistances of 3, 4, 12, 16 Q using only two metallic resistance wires either separately or joined together. What is the value of each of these wires ? 1
 

 

Q. 3. Define dielectric constant of a medium in terms of forces between electric charges. 1

 

Q. 4. The wavelengths of some of the spectral line obtained in hydrogen spectrum are 9546 A 6,463 A and 1,216 A. Which of these wavelengths belong to Lyman’s series ?
 

 

Q. 5. Write down the truth table for the combination of gates shown here.
 

 

Q. 6. In a certain arrangement a proton does not get defected while passing through a magnetic field region. Under what condition is it possible ?
 

 

Q. 7. Give the phase difference between applied voltage and the current in LCR circuit at resonance.
 

 

Q. 8. Refractive index of glass for lights of yellow, green and red colours are µ_y, µ_g, µ_r respectively. Rearrange these symbols in increasing order of values.
 

 

Q. 9. Define intensity of electric field at a point. At what point is the electric dipole field intensity is parallel to line joining them.
 

 

Q. 10. Capacitor P, Q and R have each a capacity C. A battery can charge the capacitor P to a potential difference V. If after charging P, the battery is disconnected from it and the charged capacitor is connected in the following instants to Q and R 
(i) to Q in parallel and (ii) to R in series
Then what will be the potential differences between the plates of P in two instants.

 

Q. 11. Define chemical equivalent and electrochemical equivalent of a substance. Establish a relation between them.
 

 

Q. 12. State and illustrate Curie law in magnetism.
 

 

Q. 13. How can magnetic moments of two magnets of same size and mass be compared using a vibration-magnetometer ?
 

 

Q. 14. State Lenz’s law. Show that it is a consequence of the law of conservation of energy.
 

 

Q. 15. Prove mathematically that the average power over a complete cycle of alternating current through an ideal inductor is zero.
 

 

 

Q. 16. Horizontal component of earth’s magnetic filed at a place is V3 times the vertical component. What is the value of dip at this place ?
 

 

Q. 17. Force between two electric charges kept at a distance d apart in air is F. If these charges are kept at same distance in water, how does the force between them changes ? 1
 

 

Q. 18. Give two factors on which the thermo e.m.f. produced in thermocouple depends.
 

 

Q. 19. An electric current in the direction B to A is decreasing. What is the direction of induced current in the metallic loop kept above the wire as shown in the figure.
 

 

Q. 20. Name the electromagnetic radiations used for viewing objects through haze and fog. I
 

 

Q. 21. Give the ratio of number of holes and the number of conduction electrons in an instrinsic semiconductor. 1
 

 

Q. 22. In the given diagram, is the diode D forward or reverse biased ? I
 

 

Q. 23. Name the planet which has maximum value of albedo.
 

 

Q. 24. Two charges of unknown magnitude and sign are placed a distance d apart. The electric intensity is zero at a point, not between the charges but on the line joining them. Write two essential conditions for this to happen.
 

 

Q. 25. The variation of potential difference V with length I in case of two potentiometers X and Y is shown in the given diagram. Which one of these two will you prefer for comparing e.m.f.s of the two cells and why ?
 

 

Q. 26. Name any one material having a small value of temperature coefficient of resistance. Write one use of this material.
 

 

Q. 27. Write down two advantages and two disadvantages of a secondary cell over a primary cell.
 

 

Q. 28. In figure, the straight wire AB is fixed while the loop is free to move under the influence of electric current flowing in them. In which direction does the loop begin to move ? Give reasons for your .
 

 

Q. 29. A radio frequency choke is air-cored coil whereas an audio frequency choke is iron-cored. Give reasons for the difference.
 

 

Q. 30. An astronomical telescope consists of two lenses set 36 cm apart and have magnifying power of 8. Calculate the focal length of the lenses.