Question

explain-

"Electrostatic field lines do not form any closed loops "

but if we see ncet phy part 1 pg 25 fig 1.17(d) isn't it forming closed loop b/w +q and -q

Can elecric field lines form closed loop or not ?

Answer 1

As electric field lines flow from positive to negative charge thus never come back to the positive charge, they do not form a closed loop. Imagine this as a straight one way road. But Magnetic lines form closed loops because they come back at the same pole from which they originate.

And the fig. about which you are talking is dipole formed by two equal and opposite charges.
Closed filed means going from one point to another point and then come back to the initial point. But in the fig. filed lines are going from one point to another ( positive to negative) via different directions but filed lines are not coming back to the initial point.

Hence electric field lines do not form any closed loop.