Give four properties of electric charges.

2

(a)

If the potential difference across a capacitor is doubled, what happens to :
(a) the charge on the capacitor and
(b) the energy stored in the capacitor

2

(a)

Ordinary rubber is an insulator. But the special rubber tyres of aircraft's are made slightly conducting. Why is this necessary?

2

(a)

An electric dipole is held in an uniform electric field. Using suitable diagram, show at it doesn't undergo any translatory motion, and (ii) derive an expression for torque acting on it and specify its direction.

2

(a)

At 0^oC, the resistance of a conductor B is n times that of conductor A.  The temperature coefficients of resistance of A and B are \(\alpha_1\) and \(\alpha_2\) respectively. For the series combination of the two conductors find (a) the resistance at 0^oC (b) the temperature coefficient of resistance.

2

(a)

A charge particle moving in a magnetic field penetrates a layer of lead and thereby losses half of its kinetic energy. How does the radius of curvature of its path change?

2

(a)

In a two slit experiment with monochromatic light, fringes are obtained on a screen placed at some distance D from the slits. If the screen is moved 5 x 10^-2 m towards the slits, the charge in fringe width is 3 x 10 ^-5 m. If the distance between the slit is 10-3 m . calculate the wavelength of the light used.

2

(a)

Construct AND gate using NAND GATE and give its truth table

2

(a)

What is the range of frequencies used for TV transmission?What is common between these waves and light waves?

2

(a)

Explain the terms (i) Attenuation and (ii) Demodulation used in communication system.

2

(a)

Why are high frequency carrier waves used for transmission?

2

(a)

Differentiate between (i) PAM and (ii) PPM

2

(a)

A mobile phone lies along the principal axis of a concave mirror, as shown in Fig. Show by suitable diagram, the formation of its image. Explain why the magnification is not uniform. Will the distortion of image depend on the location of the phone with respect to the mirror?

2

(a)

A lens forms a real image of an object. The distance of the object to the lens is 4 cm and the distance of the image from the lens is v cm. The given graph shows the variation of v with u.
(i) What is the nature of the lens?
(ii) Using this graph, find the focal length of this lens.

2

(a)