Ray Optics and Optical Instruments — Physics STD 12 Science — Question

An unruly demonstrator lifts a stone of mass 200g from the ground and throws it at his opponent. At the time of projection, the stone is 150cm above the ground and has a speed of 3.00m/s. Calculate the work done by the demonstrator during the process. If it takes one second for the demonstrator to lift the stone and throw, what horsepower does he use?

Is it possible to keep a parallel plate capacitor of capacity 1 Farad in your cupboard?

Explain the reflection of a plane wave using Huygen's principle.

A simple microscope is rated 5 for a normal relaxed eye. What will be its magnifying power for a relaxed farsighted eye whose near point is 40cm?

A tuning fork of frequency 256Hz produces 4 beats per second with a wire of length 25cm vibrating in its fundamental mode. The beat frequency decreases when the length is slightly shortened. What could be the minimum length by which the wire be shortened so that it produces no beats with the tuning fork?

Does the phrase "direction of zero vector" have physical significance? Discuss in terms of velocity, force etc.

Why red signals are used an danger sign? Explain.

A particle starting from rest moves with constant acceleration. If it takes 5.0s to reach the speed 18.0km/h find:

1. The average velocity during this period.
2. The distance travelled by the particle during this period.

Write the uses of Gauss's law.