A hemisphere is uniformly charged positively. The electric field at a point on a diameter away from the center is directed:(a) Perpendicular to the diameter(b) parallel to the diameter(c) At an angle tilted towards the diameter(d) At an angle tilted away from the diameter

The electric field at a point on a diameter of a uniformly charged positively charged hemisphere will be directed:

(b) parallel to the diameter

Here's why:

In a uniformly charged hemisphere, the electric field lines point away from the positively charged surface. When you consider a point on the diameter, the electric field lines will be radially outward from that point. Since the diameter is a straight line, the electric field lines will be parallel to the diameter, not perpendicular, tilted towards, or tilted away from it.