Force, Work, Energy and Power — Physics STD 10 — Question

A switch is not touched with wet hands while putting it on or off. Give a reason for your answer.

After a robbery, if a window has been broken, there will be tiny particles of glass. Some of these will be found at the scene of the crime and some may be caught in the thief’s clothing. If the police can prove that these particles are identical, they have a strong case.
A method of doing this is to suspend the particles of glass in a special liquid. Light of a single colour is thrown through the liquid and the particles viewed through a microscope. The temperature of the liquid is then slowly altered. This alters the speed of light through the liquid (i.e., it alters the refractive index). At one particular temperature, the particles of glass disappear. It this happens at the same temperature for both sets of glass particles, they probably came from the same broken pane of glass.
Complete and copy the diagram to show how light bends when it travels from the liquid to the glass and back to the liquid, If the light slows down in the glass.

State two differences between the light and sound waves.

In an experiment of finding the refractive index of glass, if blue light is replaced by the red light, how will the refractive index of glass change? Give reason in support of your answer.

State the condition when the work done by a force is negative. Explain with the help of examples.

What is radioactivity? Name two radioactive substances.

A ray of light incident at an angle of incidence i1 passes through an equilateral glass prism such that the refracted ray inside the prism is parallel to its base and emerges at an angle of emergence i2. (i) How is the angle of emergence ‘i2’ related to the angle of incidence ‘i2’. (ii) what can you say about the angle of deviation in such a situation?

(a) What are the factors on which heat absorbed by a body depends?
(b) What are the factors that effects heat given out by a body?

State two differences between a convex and a concave lens in their (a) appearence, and (b) action on the incident light.

Draw a labelled diagram of a simple a.c. generator.