Q. Threshold frequency of a certain metal for photo-electric emission is $5\times {10}^{14}$Hz. Calculate its work function.

Q. In the circuit shown in figure, E is a battery of emf $6V$ and internal resistance $1\Omega$. Find the reading of the ammeter A, if it has negligible resistance.

Q. Figure shows five dc sources(cells). Their emfs are shown in the figure. Emf of the battery AB is.

1. $8$V
2. $16$V
3. $4$V
4. $2$

Q. What conclusion was drawn by Rutherford based on Geiger-Marsden's experiment on scattering of alpha particles?

Q. Figure shows a point P near a long conductor XY carrying a current $1$. MN is a short current carrying conductor, kept at the point P, parallel to the conductor XY.
(i) What is the direction of magnetic flux density 'B' at the point P due to the current flowing through XY?
(ii) What is the direction of the force experienced by the conductor MN due to the current flowing through XY?

Q. Write a balanced nuclear reaction showing emission of a $\beta$-particles by ${}_{90}^{234}Th$. (symbol of daughter nucleus formed in the process is Pa.)

Q. A point charge of $5\times {10}^{-6}$C experiences a force of $2\times {10}^{-3}$N when kept in a uniform electric field of intensity E. Find E.

Q. A thin convex lens $\left(L_1\right)$ of focal length $80$cm and a thin concave lens$\left(L_2\right)$ of focal length f are kept co-axially, $20$cm apart as shown in figure. When a narrow and parallel beam of light is incident on the convex lens, beam emerging from the concave lens is also a parallel beam. Find f.

Q. In a moving coil galvanometer, what is meant by a radial magnetic field?

Q. A body has a positive charge of $8\times {10}^{-19}$C. It has :

1. an excess of $5$ electrons
2. a deficiency of $5$ electrons
3. an excess of $8$ electrons
4. a deficiency of $8$ electrons

Q. Which electromagnetic radiation has wavelength greater than that of X rays and smaller than that of visible light?

Q. Write an expression of magnetic flux density 'B' at a point in end-on position or an axial position of a magnetic dipole. (Derivation not required.)

Q. State Brewster's law of polarisation of light.

Q. State one important use of a Zener diode.

Q. Variation of alternating current 'I' with time 't' is shown in the graph. What is the rms value of this current?

Q. What condition must be satisfied by two thin lenses kept in contact so that they form an achromatic doublet, i.e., a combination free from chromatic aberration?

Q. Binding energy of a nucleus is of the order of.

1. Electron volt (eV)
2. Kilo electron volt (KeV)
3. Mega electron volt (MeV)
4. A joule (J)

Q. Three point charges $Q_1=25\mu$C, $Q_2=50\mu$C and $Q_3=100\mu$C, are kept at the corners A, B and C respectively of an equilateral triangle ABC having each side equal to $7.5$m. Calculate the total electrostatic potential energy of the system.

Q. Obtain an expression for equivalent capacitance C, when three capacitors having capacitance $C_1,C_2$ and $C_3$ are connected m series.

Q. What is the essential difference between the working of a nuclear reactor and that of a fission bomb?

Q. A $50\mu$F capacitor, a $30\Omega$ resistor and a $0.7$H inductor are connected in series to an ac supply which generates an emf 'e' given by $e=300\sin$ $\left(200t\right)$ Volt. Calculate peak value of the current flowing through the circuit.

Q. Which conservation principle is involved in Kirchhoff's first law of electric circuits?

Q. White light is passed through sodium vapours contained in a thin walled glass flask and the transmitted light is examined with the help of a spectrometer. The spectrum so obtained is.

1. Solar spectrum
2. Band spectrum
3. Continuous spectrum
4. Absorption spectrum

Q. On the basis of Huygen's wave theory, prove Snell's law of refraction of light.

Q. When a potential difference of $3V$ is applied between the two ends of a $60$cm long metallic wire, current density in it is found to be $1\times {10}^{-7}A{m}^{-2}$. Find conductivity of the material of the wire in SI system.

Q. How did Fresnel construct a biprism in order to study interference of light?

Q. With the help of a neatly drawn and labelled diagram, obtain balancing condition of a Wheatstone bridge.

Q. State any two differences between Peltier effect and Joule effect.

Q. Which one of the following graphs in following figure represents variation of reactance ${}^{\prime }{X}_c^{\prime }$ of a capacitor with frequency 'f' of an ac supply?

1. 
   
2. 
   
3. 
   
4. 
   

Q. What are four different types of energy losses in a transformer? State how to reducel minimize any one of them.