PHYSICS (Revised) (X)

1) Explain the difference between natural and forced vibrations of a given object.

2) A student makes a 'parallel combination' of a given number of cells. Cite one advantage and one disadvantage of this arrangement.

3) An electric heater of wattage 2kW and two light bulbs, of 60 W each, are kept 'on' for 5 hours. Find the cost of the electricity consumed if each 'unit' of electricity costs ₹2.00. 21.20

4) Why are we advised not to use wet hands for 'putting off' a switch? 

5) What is the importance of a 'fuse' in an electric circuit ?

6) Of which physical quantity is the 'kWh' a measure ? Calculate the value of 1 kWh in joule.

7) Name the three wires used in domestic wiring systems.

8) A stretched string is being made to vibrate in its 'fundamental frequency ' mode. Give two factors on which this fundamental frequency, of the vibrating stretched string, depends.

9) Soldiers are adviced to march 'out of step' while crossing bridges.

10) It is desired to find out the specific heat capacity of brass experimentally. For this purpose, 0.2 kg of hot water, at an initial temperature of 65°C, is poured into a heavy brass container of mass 1.5 kg. The brass container is initially at 15°C and gets heated up to 45°C, after pouring the hot water and stirring it well. The specific heat capacity of water is 4200 J/kg/°C.

A) How much heat energy does the hot water give out when it cools from 65°C to 45°C ? 16800 J

B) If the heat energy, released by the hot water, is totally used by the brass container, in raising its temperature from 15°C to 45°C, find the heat energy absorbed by it per degree Celsius rise in its temperature. 560 J/°C

C) What is the specific heat capacity of brass? 373.3 J kg(°C)

11) During the radioactive decay, a radioactive nucleus decays either by emitting an alpha particle or Beta particle. In both cases, it also simultaneously emits gamma rays.

A) Compare the ionising power of gamma radiation with that of alpha and beta particles.

B) How does the penetrating power of gamma rays compare with that of alpha and beta particles.

C) Do gamma rays gets deflected by electric or magnetic fields in the same ways as alpha or gamma particles get ?

D) what is the nature of charge, if any, of gamma radiation?

 

12) The isotope ²²⁶Ra₈₈ is known to decays through the emission of Alpha particles.

A) Find the change in the atomic number of the Radium nucleus when it emits an Alpha particle.

B) find the change in the mass number of the radium nucleus when it emits an Alpha particles.

C) When ²²⁶Ra₈₈ emits Alpha particles, which of the following elements is likely to be formed:

Polonium (Po₈₄); Astatine (At₈₅); Radon(Rn₈₆); Francium (Fr ₈₇ ).

C) What is the nature of

  i) alpha rays

 ii) Beta rays

 iii) gamma rays.