An object is placed 15 cm in front of a convex lens of focal length 10 cm. Find the nature and position of the image formed. Where should a concave mirror of radius of curvature 20 cm be placed so that the final image is formed at the position of the object itself?

You are given three circuit elements X, Y and Z. When the element X is connected across an a.c. source of a given voltage, the current and the voltage are in the same phase. When the element Y is connected in series with X across the source, voltage is ahead of the current in phase by π/4. But the current is ahead of the voltage in phase by π/4 when Z is connected in series with X across the source. Identify the circuit elements X, Y and Z. When all the three elements are connected in series across the same source, determine the impedance of the circuit. Draw a plot of the current versus the frequency of applied source and mention the significance of this plot.

Write symbolically the nuclear ∈+decay process of C116. Is the decayed product X an isotope or isobar of ?Given the mass values m ( ) = 11.011434 u and m (X) = 11.009305 u. Estimate the Q-value in this process.

Arrange the following electromagnetic waves in the order of their increasing wavelength:

(a) γ-rays

(b) Microwaves

(c) X-rays

(d) Radio waves

How are infra-red waves produced? What role does infra-red radiation play in (i) maintaining the Earth’s warmth and (ii) physical therapy?

Explain briefly the process of charging a parallel plate capacitor when it is connected across a d.c. battery.

A capacitor of capacitance ‘C’ is charged to ‘V’ volts by a battery. After some time, the battery is disconnected and the distance between the plates is doubled. Now a slab of dielectric constant, 1 < k < 2, is introduced to fill the space between the plates. How will the following be affected: (a) The electric field between the plates of the capacitor

(b) The energy stored in the capacitor

Justify your answer by writing the necessary expressions.