CBSE Guess > Papers > Important Questions > Class XII > 2013 > Physics > Physics - by Mr. Raghu Sharma

CBSE CLASS XII

Physics

131. Define space wave propagation?
132. Draw circuit diagram of NOR gate.
133. If Coulomb’s law involved dependence (instead of ), would Gauss’s law still true? refractive index of the material of an equilateral triangular prism is . Find the angle of minimum deviation for a monochromatic ray passing through it.
134. Prove that - I = Ane Vd.
135. Write the truth table of the following logic gate.

136. In a hydrogen atom, an electron revolves around a proton. Which of these two exerts a greater electrostatic force on the other?
137. What is the force experienced by a positively charges particle Q moving at right angles to a uniform electric field E.
138. What is the order of voltages that can be built up using a Van De Graff generator?
139. What is the angle b/w Electric field and Dipole moment at an axial point?
140. Define gyromagnetic ratio. What is it’s value?
141. State the condition in which terminal voltage across a secondary cell is equal to its emf.
142. The dielectric strength of air is 3 x 106 V/m. What is the maximum charge that can be safely stored on a sphere of radius 10m?
143. Name two types of commercially available resistors.
144. On the same graph plot the variation of E versus R and V versus R for a point charge.
145. Define mobility and mention its SI unit
146. Two resistors are connected in parallel b/w A and B to give a net resistance of 2 ohms. When one of these resistors is broken, the net resistance becomes a 3 ohms. What is the resistance of the resistor that was broken?
147. Using a suitable graph, explain why nichrome is used in standard resistance coils.
148. A velocity selector is to be designed for particles of velocity 10m/s. What magnetic field should be employed if the electric field in it is 100 N/C
149. Draw an equipotential surface for a uniform electric field.
150. In a certain arrangement a proton does not get deflected while passing through a magnetic field region. Under what condition is this possible?
151. Why does a metallic piece become very hot when it is surrounded by a coil carrying high frequency alternating current?
152. What is the focal length of a convex lens of focal length 30cm in contact with a concave lens of focal length 20cm?
153. Ultraviolet radiations of different frequencies v₁ and v₂ are incident on two photosensitive materials having work functions W₁ and W₂ (W₁ > W₂) respectively. The kinetic energy of the emitted electrons is same in both the cases. Which one of the two radiations will be of higher frequency? Draw the voltage current characteristics of a Zener diode.
154. Define electric field intensity. Write its S.I. unit. Write the magnitude and direction of electric field intensity due to an electric dipole of length 2a at the mid point of line joining the charges.
155. Define the term magnetic dipole moment of a current loop. Write the expression for the magnetic moment when an electron revolves at a speed v around an orbit of radius r in hydrogen atom.
156. In the circuit shown below, R represents an electric bulb. If the frequency v of the supply is doubled, how should the values of C and L be changed so that the glow in the bulb remains unchanged?
157. Answer the following questions:
     1. In any ac circuit, is the applied instantaneous voltage equal to the algebraic sum of the instantaneous voltages across the series elements of the circuit? Is the same true for rms voltage?
     2. Why is choke coil needed in the use of fluorescent tubes with ac mains? Why can we not use an ordinary resistor instead of the choke coil?
158. What is the equipotential due to an electric dipole at an equatorial point?
159. In a certain arrangement a proton does not get deflected while passing through a magnetic field region. Under what condition is this possible?
160. Define self induction of a coil. Write its S I unit.

Submitted By : Mr. Raghu Sharma
Email: [email protected]