Q. The smoke from a fire looks white.
Which of the following statements is true?
$1$. Molecules of the smoke are bigger than the wavelength of light.
$2$. Molecules of the smoke are smaller than the wavelength of light.

Q. Which of the wavelengths $4000\stackrel{o}{A}$ and $8000\stackrel{o}{A}$ has a higher frequency?

Q. State and define the S.I. unit of power.

Q. Name the unit of physical quantity obtained by the formula $\frac{2K}{V^2}$. Where K: kinetic energy, V: Linear velocity.

Q. You have three resistors of values $2\Omega ,3\Omega$ and $5\Omega$. How will you join them so that the total resistance is more than $7\Omega$? Draw a diagram for the arrangement.

Q. The diagram shows a lever in use.
To which class of levers does it belong?

Q. Define scattering.

Q. Displacement distance graph of two sound waves A and B, travelling in a medium, are as shown in the diagram. Study the two sound waves and compare their Amplitudes.

Q. Displacement distance graph of two sound waves A and B, travelling in a medium, are as shown in the diagram. Study the two sound waves and compare their wavelengths.

Q. The power of a lens is $-5$D. Name the type of lens.

Q. The power of a lens is $-5$D. Find its focal length.

Q. Which colour of light has a higher critical angle? Red light or Green light.

Q. How is the unit horse power related to the S.I. unit of power?

Q. Why does the amplitude of a vibrating body continuously decrease during damped vibrations?

Q. The diagram shows a lever in use.
Without changing the dimensions of the lever, if the load is shifted towards the fulcrum what happens to the mechanical advantage of the lever?

Q. State the relation between the critical angle and the absolute refractive index of a medium.

Q. State the position of the object in front of a converging lens if it produces a real and same size image of the object.

Q. The following diagram shows a ${60}^o$, ${30}^o$, ${90}^o$ glass prism of critical angle ${42}^o$. Copy the diagram and complete the path of incident ray AB emerging out of the prism marking the angle of incidence on each surface.

Q. Why is the ratio of the velocities of light of wavelengths $4000\stackrel{o}{A}$ and $8000\stackrel{o}{A}$ in vacuum $1:1$?

Q. Why is the motion of a body moving with a constant speed around a circular path said to be accelerated?

Q. What to you understand by free vibrations of a body?

Q. How is the e.m.f. across primary and secondary coils of a transformer related with the number of turns of coil in them?

Q. State the energy changes in the following case while in use.
An electric iron.

Q. State the energy changes in the following case while in use.
A ceiling fan.

Q. How can a temperature in degree Celsius be converted into S.I. unit of temperature?

Q. Nuclear power plants use nuclear fission reaction to produce electricity. What is the advantage of producing electricity by fusion reaction?

Q. State the position of the object in front of a converging lens if it is used as a magnifying lens.

Q. On which type of current do transformers work?

Q. What do you understand by the term nuclear fusion?

Q. You have three resistors of values $2\Omega ,3\Omega$ and $5\Omega$. How will you join them so that the total resistance is more than $7\Omega$? Calculate the equivalent resistance.