Q. What are mechanical waves?

Q. Name a common device that uses electromagnets.

Q. An electron emitter must have _____ work function and ______ melting point.

Q. Two forces each of $5N$ act vertically upwards and downwards respectively on the two ends of a uniform metre rule which is placed at its mid-point as shown in the diagram. Determine the magnitude of the resultant moment of these forces about the midpoint

Q. When does a force do work?

Q. Find the equivalent resistance between points $A$ and $B$.

Q. A force is applied on:

Q. The conversion of part of the energy into an undesirable form is called ______

Q. State one important advantage and disadvantage each of using nuclear energy for producing electricity.

Q. A body is thrown vertically upwards. Its velocity keeps on decreasing. What happens to its kinetic energy as its velocity becomes zero?

Q. Which colour of light travels fastest in any medium except air?

Q. Draw the diagram given below and clearly show the path taken by the emergent ray

Q. Is it possible to have an accelerated motion with a constant speed? Explain

Q. State the energy changes in the following devices while in use:
(i) A loud speaker

Q. Calculate the change in the kinetic energy of a moving body if its velocity is reduced to $1/3rd$ of the initial velocity.

Q. What is nuclear energy?

Q. A ray of light passes from water to air. How does the speed of light change?

Q. Name the radiations which can be detected by a thermopile.

Q. Name the factors affecting the critical angle for the pair of media.

Q. Name one property of waves that do not change when the wave passes from one medium to another

Q. Draw a diagram to show how a single pulley can be used so as to have its ideal Mechanical Advantage $(M.A.)=2$

Q. What is the principle of an ideal machine?

Q. Name a prism required for obtaining a spectrum of ultraviolet light.

Q. For a given height h, ____ the length of the inclined plane, lesser will be the effort required.

Q. What is the work done by the moon when it revolves around the earth?

Q. What is consumed by different electrical appliances, for which electricity bills are paid?

Q. A man having a box on his head, climbs up a slope and another man having an identical box walks the same distance on a levelled road. Who does more work against the force of gravity and why?

Q. A metallic ball is hanging by a string from a fixed support. Draw a neat labelled diagram showing the force acting on the ball and the string

Q. $50g$ of metal piece at ${27}^{\circ }C$ requires $2400J$ of heat energy so as to attain a temperature of ${327}^{\circ }C$. Calculate the specific heat capacity of the metal.

Q. What is the weight of a body placed at the centre of the earth?