Q. What is meant by the terms half-life of a radioactive substance and binding energy of a nucleus?

Q. The order of coloured rings in a carbon resistor is red, yellow, blue and silver. The resistance of the carbon resistor is :

1. $24\times {10}^6\Omega \pm 5\%$
2. $24\times {10}^6\Omega \pm 10\%$
3. $34\times {10}^4\Omega \pm 10\%$
4. $26\times {10}^4\Omega \pm 5\%$

Q. An object is kept on the principal axis of a concave mirror of focal length $10$cm, at a distance of $15$cm from its pole. The image formed by the mirror is?

1. Virtual and magnified
2. Virtual and diminished
3. Real and diminished
4. Real and magnified

Q. How will you convert a moving coil galvanometer into a voltmeter?

Q. Define coherent sources of light.

Q. Einstein's photoelectric equation is?

1. $E_{max}=\frac{hc}{\lambda }+2{\phi }_0$
2. $E_{max}=h\nu -{\phi }_0$
3. $E_{max}=hv+{\phi }_0$
4. $E_{max}=\frac{2hc}{\lambda }+{\phi }_0$

Q. A moving charged particle q travelling along the positive x-axis enters a uniform magnetic field B. When will the force acting on q be maximum?

Q. Name an electromagnetic wave which is used in the radar system used in aircraft navigation. Give another use of the wave.

Q. Calculate the minimum wavelength of the spectral line present in Balmer series of hydrogen.

Q. In Bohr's model of hydrogen atom, radius of the first orbit of an electron is $r_0$. Then, radius of the third orbit is?

1. $r_0$
2. $3r_0$
3. $9r_0$
4. $\frac{r_0}{9}$

Q. A biconvex lens made of glass(refractive index $1.5$) has two spherical surfaces having radii $20$cm and $30$cm. Calculate its focal length.

Q. A circular coil carrying a current I has radius R and number of turns N. If all the three, i.e., the current I, radius R and number of turns N are doubled, then magnetic field at its centre becomes.

1. Half
2. Double
3. One fourth
4. Four times

Q. A long horizontal wire P carries a current of $50$A. It is rigidly fixed. Another wire Q is placed directly above and parallel to P, as shown in Figure. The weight per unit length of the wire Q is $0.025$ $N{m}^{-1}$ and it carries a current of $25$A. Find the distance 'r' of the wire Q from the wire P so that the wire Q remains at rest.

Q. A rectangular coil having $60$ turns and area of $0.4m^2$ is held at right angles to a uniform magnetic field of flux density $5\times {10}^{-5}$T. Calculate the magnetic flux passing through it.

Q. In a potentiometer experiment, balancing length is found to be $120$cm for a cell $E_1$ of emf $2V$. What will be the balancing length for another cell $E_2$ of emf $1.5$V? (No other changes are made in the experiment.)

Q. What is motional emf? State any two factors on which it depends.

Q. What is meant by pair annihilation? Write a balanced equation for the same.

Q. Explain Curie's law for a paramagnetic substance.

Q. In a communication system, what is meant by modulation? State any two types of modulation.

Q. State any two difference between primary rainbow and secondary rainbow.

Q. ${\epsilon }_1$ and ${\epsilon }_2$ are two batteries having emf of $34$V and $10$V respectively and internal resistance of $1\Omega$ and $2\Omega$ respectively. They are connected as shown in Figure. Using Kirchhoff's Laws of electrical networks, calculate the currents $I_1$ and $I_2$.

Q. Ordinary (i.e., unpolarised) light is incident on the surface of a transparent material at the polarising angle. If it is partly reflected and partly refracted, what is the angle between the reflected and the refracted rays?

Q. Deduce an expression for equivalent capacitance C when three capacitors $C_1$, $C_2$ and $C_3$ are connected in parallel.

Q. With reference to photoelectron effect, define threshold wavelength.

Q. Calculate force per unit length acting on the wire B due to the current flowing in the wire A.

Q. Name a material which is used in making control rods in a nuclear reactor.

Q. Define current density. Write an expression which connects current density with drift speed.

Q. Obtain an expression for intensity of electric field at a point in end on position, i.e., axial position of an electric dipole.

Q. What is the ratio of the speed of gamma rays to that of radio waves in vacuum?

Q. State de Broglie hypothesis.