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1.Ultra-violet light of wave-length 200 nm is incident on polished surface of Fe.Work Function of the surface is 4.7 eV

Find .-

(i) Stopping Potential;

(ii) Maximum Kinetic energy of Photo electrons.

(h = 6.6x 10-34 J. sec., C = 3 x 108 ms 1, 1 eV = 1. 6 x 10-19 J.,m = 9.1 x 10-31 Kg.)

2. An object is placed at a distance of 25 cm. on the axis of a concave mirror having focal length of 20 cm. Find the image distance, type of the image and its lateral magnification.

3. In Fraunhofer diffraction by a single slit, a position where first order minimum is formed by the wave-length of 6000 A, first order maximum is formed due to an unknown wave-length V. Find X’

4. In Young’s experiment, a beam of light of wave-length 6500 A and 5200 A is used. Find the maximum distance from the central bright fringe, where bright fringes produced by both the wave-length get super-posed. The distance between the two slits is 0.5 mm and the distance between the slits and screen is 100 cm.

5. L and R are connected in series with an AC voltage. The maximum value of the AC voltage is equal to 220 V. Calculate the power consumed in the circuit as well as the power factor. The reactance of the coil is equal to 40 52 and R 30 Q.

6. % of the total energy of a 10O W bulb is converted into visible light. Calculate the average intensity at a spherical surface which is at a distance of 1 in from the bulb. Consider the bulb to be a point source and let the medium be isotropic.

7. When a linear object is placed in front of a convex mirror, image of the 4th size of the object is formed. Calculate the object distance and the image distance. This linear object is kept perpendicular to the axis.

8. An inductor L = 8.1 mH is connected in series with a capacitor C = 12.5 µF and a resistor is R = 10 Q. The series combination of R-L-C is connected to an A.C. voltage of 100 V and 500 Hz frequency. Calculate the voltage developed between the two ends of the resistor.

9. An A.C. source of 230 V is connected in series with 5 H inductor, 80 µ F capacitor and a 40 52 resistor.

(i) Find resonant frequency (fo).

(ii) Find the impedance of the circuit and the value of the current at resonant frequency.

10. A conducting bar of 2 m length is allowed to fall freely from a 50 m high tower,keeping it aligned along the east-west direction. Find the em f induced in the rod, when it is 20 m below from the top of the tower. g =10ms 2, Horizontal component of earth’s magnetic field is 0.7 x 10-4 T and angle of Dip = 60°.

11. A toroidal core with 3000 turns has inner and outer radii of 11 cm. and 12 cm.respectively. When a current of 0.70 A is passed , then the magnetic field produced in the core is 2.5 T. Find the relative permeability of the core.

( go = 4n x 10-7 Tm A-‘).

12. An emf of 412.5 µV is developed in a Fe-Cd thermocouple when its cold junction is at 0°C and hot junction at 30°C. When hot junction is kept at 100°C, 1200µV emf is produced, then find constants a and 0 of thermo-couple.

13. q, = 2µC electric charge is placed at origin of Cartesian Co-ordinate System. Another q2 =- 3µC charge is placed on the X-axis at a distance x =100 cm. At which points along the X-axis, will be the electric potential equal to zero?

14. There are 1.5 x 104 turns in the winding of a toroidal ring. The radius of circular axis of the ring is 10 cm. The radius of cross-section of ring is 2.0 cm. Find inductance of the ring. (90 = 47t x 10-7 SI) .

15. Write the equation of magnetic force acting on a particle moving through a magnetic field. Using it, obtain Newton’s equation of motion and show that Kinetic Energy of the particle remains constant with time.

16. n electric kettle has two heating coils. When one of this coil is switched on, a given quantity of water in the kettle starts boiling in tl minutes. When the other coil only is switched on, then the same amount of water starts boiling in t2 minutes. If the two coils are switched on in parallel, prove that the same amount of water will take time is the same.

t = tlt2

ti + t2

to boil. Each time the voltage applied

16. A 900 pF capacitor is charged with the help of 100 V battery. Calculate the steady electric energy on this capacitor. The above capacitor is disconnected from the battery and is connected to another identical capacitor. What will be the total energy of the system?

17. A charge of 4×10-8 C is uniformly distributed all over the surface of a sphere of radius 1 cm. Another hollow sphere of radius 5 cm is concentric with smaller sphere. Find intensity of electric field at a distance of 2 cm from the centre.

K= 9x109SI.

18. The co-ordinates of two electric charges qA = 2.5 x 10-7 C and qB = -2.5 x 10-7 C are (0, 0, -15) cm and (0, 0, 15) cm. Calculate the total electric charge and dipole moment of this system.

19. A 40 gC of electric charge is placed at the origin of the Cartesian co-ordinate system. Calculate the electric potential at a point (0.5, 0.8, 0.6) m.

k=9x109SI.

20. Explain Analog and Digital Communication.

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