Question

Two small charged spheres A and B have charges 10 u C and 40 u C
respectively kept at a distance of 90 cm. At what distance from A the
electric field intensity become zero?
22.5 cm
18 cm
. 30 cm
.. 36 cm
3​

Answer 1

Answer:

Given that two small charged spheres A and B have charges of 10 u C and 40 u C kept at a distance of 90 cm.

We have to find the distance from A where electric field intensity is zero.

Let's start with basic :

Let the distance from A be y cm where electric field intensity will be zero and electric field intensity of A will be equal to electric field intensity of B.

We know,

Electric field intensity = kq/x²

Now distance from B will be (90 - y) cm

According to question :

⟼ k(10)/y² = k(40)/(90 - y)²

⟼ 10k/y² = 40k/(90 - y)²

Dividing both by (10k) :

⟼ 1/y² = 4/(90 - y)²

Squaring root on both sides :

⟼ √(1/y²) = √{4/(90 - y)²}

⟼ 1/y = 2/(90 - y)

⟼ 2y = 90 - y

⟼ 2y + y = 90

⟼ 3y = 90

⟼ y = 90/3

⟼ y = 30 cm

∴ Distance from A will be 30 cm where electric field intensity will be zero.

∴ Correct option : b) 30 cm.

Answer 2

Answer:

answer is 30 cm

Explanation:

just put the values