Question

The figure shows the E-field in the plane of two point charges.
True False  Q₁ is negative.
True False  The size of Q₁ is larger than that of Q₂.
True False  A + charge at c would accelerate to the left.
True False  A − charge at a would accelerate to the right.
True False  The magnitude of E is the same at a and b.
True False  Q₁ and Q₂ have the same sign.

Answer 1

From figure, we can see that from $Q_{2}$ flux lines are flowing outwards and hence is a Positive charge.
Also, from $Q_{1}$ flux lines are flowing inwards and hence is negative charge

So, $Q_{1}$ is negative  TRUE

b) We can see that electric flux lines are closer towards each other in $Q_{1}$ as compared to $Q_{2}$. hence we can say that $Q_{1}$ has more magnitude than $Q_{2}$.
So, Size of $Q_{1}$ is larger than $Q_{2}$.  TRUE

c) Suppose a + charge is kept at c. The $Q_{2}$ would repel but $Q_{1}$ will attract. Hence, the charge would deccelerate and an equilibrium would be reached.
So, A + charge at c would accelerate to the left. FALSE

d) A − charge at a would accelerate to the right. TRUE
Suppose a -ve charge is kept at a. The $Q_{2}$ would attract but $Q_{1}$ will repel. Hence, a force in same direction towards left acts at a due to both charges, hence the charge kept at a would accelerate.

e)  Q₁ and Q₂ have the same sign. FALSE [explained earlier]