JEE Advanced2009PhysicsMagnetic Effects of CurrentActual
Two metallic rings A and B , identical in shape and size but having different resistivities _A and _B , are kept on top of two identical solenoids as shown in the figure. When current I is switched on in both the solenoids in identical manner, the rings A and B jump to heights h_A and h_B , respectively, with h_A>h_B . The possible relation(s) between their resistivities and their masses m_A and m_B is(are)
Options
- A_A> _B and m_A=m_B
- B_A < _B and m_A=m_B
- C_A> _B and m_A>m_B
- D_A < _B and m_A < m_B
Correct answer
B. _A < _B and m_A=m_B
Step-by-step solution
Induced emf e=- d d t . For identical rings induced emf will be same. But currents will be different. Given h_A>h_B . Hence, v_A>v_B as (h= v^2 2 g ) . If _A> _B , then, I_A I_B . In this case given condition can be fulfilled of m_A m_B .