The unit of electric current "ampere" is the current which when flowing through each of two parallel wires spaced 1 m apart in vacuum and of infinite length will give rise to a force between them equal to

Question

The unit of electric current "ampere" is the current which when flowing through each of two parallel wires spaced 1 m apart in vacuum and of infinite length will give rise to a force between them equal to (A) 1 N / m (B) 2 × 10-7 N / m (C) 1 × 10-2 N / m (D) 4 π × 10-7 N / m

Tardigrade Admin · Accepted Answer

Force per unit length on two parallel current carrying conductor is given by (F/ℓ)=10-7 × 2 (i1 i2/a) ⇒ (F/ℓ)=10-7 × 2 × (1 × 1/1) =2 × 10-7 N / m

Q. The unit of electric current "ampere" is the current which when flowing through each of two parallel wires spaced $1 m$ apart in vacuum and of infinite length will give rise to a force between them equal to

$1 N / m$

$2 \times 1 0^{- 7} N / m$

$1 \times 1 0^{- 2} N / m$

$4 π \times 1 0^{- 7} N / m$

Force per unit length on two parallel current carrying conductor is given by
$\frac{F}{ℓ} = 1 0^{- 7} \times 2 \frac{i _{1} i _{2}}{a}$
$\Rightarrow \frac{F}{ℓ} = 1 0^{- 7} \times 2 \times \frac{1 \times 1}{1}$
$= 2 \times 1 0^{- 7} N / m$

Q. The unit of electric current "ampere" is the current which when flowing through each of two parallel wires spaced 1m apart in vacuum and of infinite length will give rise to a force between them equal to

1N/m

2×10−7N/m

1×10−2N/m

4π×10−7N/m