in simple pendulum if we change the iron bob with lead bob then what effect on time period

Dear student 
The ans is No.
The mass of the bob does not affect the period.
the size or shape of the bob might matter, in the sense that it affects the pendulum’s overall moment of inertia. And changing the material of the bob from iron to lead could have a significant effect in the presence of a high magnetic field (lead is nonmagnetic at ordinary temperatures).

Time period is = 2π√l/g

It means the time period is independent of mass so time period will not be affected whether we use metal or wooden bob or lead bob.

 

So it will remain same.

 

Dear friends;

As,we know  TIME PERIOD depends on length and acc.due to gravity of the planet,but does not depends on the nature of the material with which the pendulum has made., So,no effect is observed in the time period