State whether the following statements are True (T) or False (F):
The power of a lens is 4D. The focal length is 50 cm.

State whether the following statements are True (T) or False (F): A cell is a source of electrons.

State whether the following statements are True (T) or False (F): In Boolean algebra (A+A) = A.

State whether the following statements are True (T) or False (F): Electric field is a scalar field.

State whether the following statements are True (T) or False (F): The emf of a cell is always equal to the terminal p.d of the cell.

State whether the following statements are True (T) or False (F): The charge of a body may be 2 xx 10^19C .

State whether the following statements are True (T) or False (F) : The speed of light in glass is less than the speed of light in water.

State whether the following statements are True (T) or False (F): The charging equation of a cell is V= E + Ir.

State whether the following statements are True (T) or False (F): The nature of the lens changes when it is immersed in a medium whose refractive index is more than the refractive index of the material of the lens.

State whether the following statements are True (T) or False (F): In the process of charging a body only electrons take active part.

State whether the following statements are True (T) or False (F): A cell is preferably a source of chemical energy.