Take Pure

20.    What force must be applied to a steel wire 6 m long and diameter 1.6 mm to produce an extension of 1 mm? (Y for steel = 2X10 11 N/m 2 ).

19.    Two slits in Young’s double slit experiment are 0.18 mm apart and fringes are observed on a screen 80 cm away. If the fourth bridge fringe is situated at a distance of 10.8 mm from center fringe, find the wavelength of light.

18.    At what temperature will be velocity of sound is double its value at 273 K?

15.    What is the impedance of a series combination of a resistance 1000 Ω and a capacitance of 2 µF at a frequency of 50 Hz?

14.    An electric lamp is rated as 220 V – 100 W. What is its electric resistance? What power does it consume if it used a circuit of 110 V?

13. Two small spheres of charge +10 µC and +40 µC are placed 6 cm apart. Find location of point between them where the field strength is zero.

5 g) Calculate the velocity of sound in air if two waves of wavelength 0.5 m and 0.505 m produce 5 beats per second.

5 d) Two spherical rain drops of equal size are falling vertically through air with terminal velocity of 0.15 m . What would be terminal velocity if these two drops were to coalesce to form a large spherical drop?

5 c) In an A.C circuit, a resistor of resistance 1000 Ω and capacitor of capacitance 10 µF are connected in series with a source of 220 V and 50 Hz. Find the impedance of circuit and current flowing through circuit.

5.a) Two charges each of 10 -9  m are 8 cm apart in air. Find the magnitude of force exerted by these charges on third charge of 5x10 -11  C at a distance of 4 cm from each of charge. Given; K=9x10 9  Nm 2 C -2

5.b) A galvanometer has an internal resistance of 1Ω. It gives full scale deflection for a current of 50 mA. How this instrument can be converted into a voltmeter with a maximum range of 2.5 v.