Answer:
The magnitude of force is 1.86 N and the direction of force is towards the other wire.
Explanation:
Given:
Current flowing through each power line, I = 130 A
Distance between the two power lines, d = 40 cm = 0.4 m
Length of power lines, L = 220 m
The force exerted by the power lines on each other is given by the relation:

Substitute the suitable values in the above equation.

F = 1.86 N
Since the direction of current flowing through the power lines are opposite to each other, so the force is attractive in nature. Hence, the direction of force experienced by the power lines on each other is towards the each other.
Answer:
λ = 470.66 nm
Explanation:
for bright fringe
D= distance between slit and screen
d= distance between the slits
for first order bright fringe m = 1,


for dark fringe,we have
Now to get the dark fringes at the same location we should have;
(706)D/d = (m + 1/2)λD/d
put m = 1
(1 + 1/2)λ = (706)
λ = 470.66 nm
Answer:

where E = electric field intensity
Explanation:
As we know that plastic ball is suspended by a string which makes 30 degree angle with the vertical
So here force due to electrostatic force on the charged ball is in horizontal direction along the direction of electric field
while weight of the ball is vertically downwards
so here we have


since string makes 30 degree angle with the vertical so we will have





where E = electric field intensity