Define magnifying power of a telescope. Write its expression. A small telescope has an objective lens of focal length 150 cm and an eye-piece of focal length 5 cm. If this telescope is used to view a 100 m high tower 3 km away, find the height of the final image when it is formed 25 cm away front the eye-piece.

How is the working of a telescope different from that of a microscope? The focal lengths of the objective and eyepiece of a microscope are 1.25 cm and 5 cm respectively. Find the position of the object relative to the objective in order to obtain an angular magnification of 30 in normal adjustment.

Draw a simple circuit of a CE transistor amplifier. Explain its working. Show that the voltage gain, Av, of the amplifier is given by AV=−βacRL/ri
where βac is the current gain,
‘ RL’ is the load resistance and,
‘ ri ‘ is the input resistance of the transistor.
What is the significance of the negative sign in the expression for the voltage gain ?

(a) Draw the circuit diagram of a full wave rectifier using p-n junction diode. Explain its working and show the output, input wave forms.
(b) Show the output wave forms (Y) for the following inputs A and B of
(i) OR gate
(ii) NAND gate

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