Q. Write four differences between interference and diffraction.

Q. At what distance in front of a concave mirror of focal length $10$cm, an object be placed so that its real image of size five times that of the object obtain?

Q. At polarising angle, the angle between the reflected ray and refracted ray from a surface _______.

Q. If full scale of deflection is obtained in galvanometer of resistance $99$ ohms by passing current ${10}^{-4}$A in it, what arrangement is required to measure a current of $1$A from it?

Q. The potential difference between the two plates of a parallel plate capacitor is constant. When air between the plates is replaced by dielectric material, the electric field intensity :

1. Becomes zero
2. Remains unchanged
3. Increases
4. Decreases

Q. Unit of specific resistance is.

1. $Oh{m}^{-1}$
2. Ohm
3. Ohm $metre$
4. $Oh{m}^{-1}metr{e}^{-1}$

Q. What is meant by population inversion and optical pumping?

Q. Find energy of photon of wavelength $4000\stackrel{o}{A}$.

Q. Differentiate between the P and N type semiconductors.

Q. State Gauss theorem and uses it to derive the Coulomb's inverse square law.

Q. The intensity of electric field E due to charge Q at distance r.

1. $E\propto r$
2. $E\propto \frac{1}{r^3}$
3. $E\propto \frac{1}{r}$
4. $E\propto \frac{1}{r^2}$

Q. A moving charge produces.

1. Only electric field
2. Both electric and magnetic fields
3. Only magnetic field
4. Neither the electric field nor the magnetic field

Q. If length of a wire is doubled after stretching, then what will be its resistance?

Q. Write four laws of photoelectric effect.

Q. Equivalent resistance when $2$ and $3$ ohm resistances are connected in series is _______.

Q. Write the Lenz's law.

Q. The time period of communication satellite is ___________.

Q. What are electromagnetic waves? Write its nature.

Q. Three resistors $R_1,R_2,R_3$ are joined in series. Draw labelled diagram and obtain expression of its equivalent resistance.

Q. A straight wire of length l and magnetic moment m is bent into shape of semicircle, then what will be new magnetic moment?

Q. $i_p+r=$ __________.

Q. The expression for capacity of a spherical conductor is.

1. $C=\frac{1}{4\mu {ϵ}_{0}R}$
2. $C=4\pi {ϵ}_0{R}^3$
3. $C=4\pi {ϵ}_0{R}^2$
4. $C=4\pi {ϵ}_{0}R$

Q. When a copper plate is placed below an oscillating magnetic needle, the magnetic needle soon stops but if a glass plate is placed below, it does not stop. Give reasons.

Q. Derive the relationship between the focal length and radius of curvature of spherical mirror.

Q. What is meant by electric flux? Write its S.I. unit and dimensional formula.

Q. Match the right pairs.

Q. Describe terrestrial telescope on the basis of the following points:
(i) A clear labelled diagram;
(ii) Expression for magnifying power when the final image is at least distance of distinct vision D.

Q. If length of astronomical telescope is $80$cm and its magnification is $15$, then find focal length of objective lens and eyepiece.

Q. The sound waves are the longitudinal waves. The electromagnetic waves are ________.

Q. What are carrier waves? Why do we need the carrier waves of high frequency for distant communication?