Two point charges Q and +q (where q is positive) produce the net electric field shown at point P in Fig. The field points parallel to the line connecting the two charges. (a) What can you conclude about the sign and magnitude of Q? Explain your reasoning. (b) If the lower charge were negative instead, would it be possible for the field to have the direction shown in the figure? Explain your reasoning.

When charge is present in any form, a point in space has an electric field that is connected to it. The value of E, often known as the electric field strength, electric field intensity, or just the electric field, expresses the strength and direction of the electric field.

(a)

Since the net filed is in vertical direction that horizontal component of fields must be zero so the charge Q must be zero.

Hence, q is negative and magnitude is zero

(b)

No, the electric field component of p in horizontal direction will be in the same direction as Q so the horizontal component will exist and for that p must not be negative, more over the direction of vertical component will depend on value of Q and p so we won’t make sure the exact direction.

Hence, no it’s not possible