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CBSE CLASS XII

Physics

161. Name the radiations which are next to IR radiations in electromagnetic spectrum having
162. Shorter wavelength  & (ii) Longer wavelength
163. Two thin lenses of power +6D and -2D are in contact. What is the focal length of the combination?
164. The stopping potential in an experiment on photoelectric effect is 1.5V. What is the maximum kinetic energy of the emitted photoelectrons?
165. Draw the voltage current characteristics of a Zener diode.
166. What is the nuclear radius of 125Fe if that of 27Al is 3.6 fermi?
167. A diverging lens of focal length ‘F’ is cut into two identical parts each forming a plano-concave lens. What is the focal length of each part?
168. How does resolving power of an astronomical telescope get affected on
     1. increasing the aperture of objective lens?
     2. increasing the wavelength of light used?
169. How does the  stopping potential applied to a photocell change, if the distance between the light source and the cathode of the cell is doubled?
170. A 500µc charge is at the centre of a square of side 10 cm. Find the work done in moving a charge of 10µc between two diagonally opposite points on the square.
171. Zener diodes hhave higher dopant densities as compared to ordinary p-n junction diodes. How does it affect the
     1. Width of the depletion layer?
     2. Junction field?
172. Name the characteristics of electromagnetic waves that
     1. Increases
     2. remains constant
173. in an electromagnetic spectrum as one moves from radio wave region towards ultraviolet region.What happens?
174. If an electron and a proton having same momenta enter perpendicularly to a magnetic field, how will you compare the nature of the path followed by them?
175. A 50 Hz ac source of 20V is connected to a series combination of resistor R and capacitor C. The voltage across R is 12V, what is the voltage across C?
176. Let the wavelengths of electromagnetic waves used quite often for:
177. killing of germs in a household water purifiers,
     1. b.remote sensing&
     2. treatment of cancer
     3. be labelled as λ₁, λ₂ & λ₃. Arrange λ₁, λ₂ & λ₃ in increasing order.
178. A ray falls on a prism ABC ( AB = BC ) and travels as shown in the fig 1. What is the least value of refractive index of material of the prism?
179.  When photons energy hn are incident on the surface of photosensitive material of work function hno, what is the kinetic energy of the ejected electrons?
180. The TV signals have a bandwidth of 4.7MHz. What is the number of channels in a bandwidth of 4700GHz?
181. Two identical charged particles moving with same speed enter a region of uniform magnetic field. If one of these enters normal to the field direction and the other enters along a direction at 300 with the field, what would be the ratio of their angular frequencies?
182. Why does a metallic piece become very hot when it is surrounded by a coil carrying high frequency alternating current?
183. How is a sample of an n-type semiconductor electrically neutral though it has an excess of negative charge carriers?
184. Name the characteristics of electromagnetic waves that
     1. increases
     2. remains constant in the electromagnetic spectrum as one moves from radiowave region towards ultravoilet region.
185. How would the angular separation of interference fringes in young’s double slit experiment change when the

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