1. Define capacitor reactance. Write its S.I. units. 

2. What is the electric flux through a cube of side 1 cm which encloses an electric dipole? 

3.

Graph showing the variation of current versus voltage for a material GaAs is shown in the figure. Identify the region of

i) negative resistance

ii) where Ohm’s law is obeyed.    

                         

4. Use Kirchhoff’s rules to obtain conditions for the balance condition in a Wheatstone bridge.

5.

Name the parts of the electromagnetic spectrum which is

(a) suitable for radar systems used in aircraft navigation.

(b) used to treat muscular strain.

(c) used as a diagnostic tool in medicine.

 Write in brief, how these waves can be produced.     

6.

A cell of emf ‘E’ and internal resistance ‘r’ is connected across a variable load resistor R. Draw the plots of the terminal voltage V versus
(i) R and
(ii) the current I.

It is found that when R = 4 Ω , the current is 1 A and when R is increased to 9 Ω , the current reduces to 0.5 A. Find the values of the emf E and internal resistance r.

7.

Two capacitors of unknown capacitances C₁  and C₂  are connected first in series and then in parallel across a battery of 100 V. If the energy stored in the two combinations is 0.045 J and 0.25 J respectively, determine the value of C₁  and C₂. Also, calculate the charge on each capacitor in parallel combination.

8.

State the principle of working of a galvanometer.

A galvanometer of resistance G is converted into a voltmeter to measure upto V volts by connecting a resistance R₁ in series with the coil. If a resistance R₂  is connected in series with it, then it can measure upto V/2 volts. Find the resistance, in terms of R₁ and R₂, required to be connected to convert it into a voltmeter that can read upto 2 V. Also find the resistance G of the galvanometer in terms of R₁ and R₂. 

9.

An inductor L of inductance X_L is connected in series with a bulb B and an ac source.

How would brightness of the bulb change when (i) number of turn in the inductor is reduced, (ii) an iron rod is inserted in the inductor and (iii) a capacitor of reactance X_C = X_L  is inserted in series in the circuit. Justify your answer in each case.   

10. A concave lens of refractive index 1.5 is immersed in a medium of refractive index 1.65. What is the nature of the lens ?