Dual Nature of Radiation and Matter — Physics STD 12 Science — Question

Why do stable nuclei never have more protons than neutrons?

Explain controlled thermonuclear fusion.

The 200m free style women's swimming gold medal at Seol Olympic 1988 went to Heike Friendrich of East Germany when she set a new Olympic record of 1 minute and 57.56 seconds. Assume that she covered most of the distance with a uniform speed and had to exert 460W to maintain her speed. Calculate the average force of resistance offered by the water during the swim.

Explain the proof of validity of Einstein's equation of photoelectric effect.

Write the function of a (i) Transducer and (ii) Repeater in a communication system.

A block suspended from a vertical spring is in equilibrium. Show that the extension of the spring equals the length of an equivalent simple pendulum i.e., a pendulum having frequency same as that of the block.

Sunita and her friends went to an exhibition. The guard standing there asked them to pass through a metal detector. Sunita's friends were first afraid but when Sunita told them the reason and explain its working.
Answer the following questions :
(a) State the principle on which metal detector works.
(b) If a person passing through metal detector has some metallic object then why does it produces sound?
(c) Tell two qualities of Sunita which she showed while explaining the reason for passing through it.

Write Snell's law and derive its general equation.

Explain Ohm's law.