Answer:
Explanation:
Given
charge is placed at 
another charge of
is at 
We know that Electric field due to positive charge is away from it and Electric field due to negative charge is towards it.
so net electric field is zero somewhere beyond negatively charged particle
Electric Field due to
at some distance r from it

Now Electric Field due to
is

Now 



thus 
Thus Electric field is zero at some distance r=1.43 cm right of
Answer:
ΔT= 11.94 °C
Explanation:
Given that
mass of water = 10 kh
Time t= 15 min
Heat lot from water = 400 KJ
Heat input to the water = 1 KW
Heat input the water= 1 x 15 x 60
=900 KJ
By heat balancing
Heat supply - heat rejected = Heat gain by water
As we know that heat capacity of water


Now by putting the values
900 - 400 = 10 x 4.187 x ΔT
So rise in temperature of water ΔT= 11.94 °C