Question

(a) The diagram shows a coil wound around a U shape soft iron bar AB. 

(i) What is the polarity induced at the ends A and B when the switch is pressed? 

(ii) Suggest one way to strengthen the magnetic field in the electromagnet. 

(iii) What will be the polarities at A & B if the direction of current is reversed in the circuit?

 

(b) The ore of Uranium found in nature contains 92U238 and 92U235. Although both the isotopes are fissionable, it is found out’experimentally that one of the two isotopes is more easily fissionable. 

(i) Name the isotope of Uranium which is easily fissionable. 

(ii) Give a reason for your, answer.

(iii) Write a nuclear reaction when Uranium 238 emits an alpha particle to form a Thorium (Th) nucleus.  

(c) Radiations given out from a, source when subjected to an electric field in a direction perpendicular to their path are shown below in the diagram. The arrows show the path of the radiation A, B and C. Answer the following questions in terms of A, B and C.  

(i) Name the radiation B which is unaffected by the electrostatic field. 

(ii) Why does the radiation C deflect more than A?

 

(iii) Which among the three causes the least biological damage externally? 

(iv) Name the radiation which is used in carbon dating.

Answer 1

(i) A north and B south 

(ii) Increasing the current through the coil. 

(iii)A South and B North 

(b) (i) 92u235 

(ii) It readily absorbs thermal neutrons and becomes unstable.

 (iii) The reaction is 92U238 → 90Th234 + 2He4 

(c) (i) Gamma radiation 

(ii) Because it is lighter than A.

 (iii) Alpha (A) 

(iv) Carbon-14