Answer:
8 x 10⁻⁷ x I / r
Explanation:
Two parallel long wires are carrying current I . Let the direction be towards the right in the farthest and towards the left in the nearest. Magnetic field due to current I at a distance d is given by the expression
B = μ₀ 2 I / 4π d
I the present case distance d = r/2
Magnetic field due to one wire at point d = r/2 is
B₁ = μ₀ 2 I / (4π r / 2 )
= 10⁻⁷ x 4I / r
Magnetic field due to the other wire at point d = r/2 is
B₂ = μ₀ 2 I / (4π r / 2 )
= 10⁻⁷ x 4I / r
Direction of magnetic field due to both the wires at the mid point P will be same . It will be in downward direction in the given scenario
So total magnetic field
B = B₁ + B₂
= 2 x 10⁻⁷ x 4I / r
= 8 x 10⁻⁷ x I / r
Answer:
Explanation:
Object is Floating in a liquid
weight of object is equal to weight of displaced fluid
i.e.

i.e.
where V and V' is the volume of object and volume of object inside the liquid.
therefore mass of liquid displaced must be equal to mass of object
Answer:
The current in a resistor decreases by a factor of 4.
Explanation:
I = 
Where (I) is the current, (E) is the voltage and (R) is the resistance.
Decreasing the voltage by 4 gives;
I = 0.25
Since you have multiplied
by 0.25,
You have to multiply I by 0.25 so the current decreases by a factor of 4.