<P> Measuring the angles θ and θ and the distance between the charges L and L is sufficient to verify that the equality is true taking into account the experimental error . In practice, angles can be difficult to measure, so if the length of the ropes is sufficiently great, the angles will be small enough to make the following approximation: </P> <Table> <Tr> <Td> <P> </P> <Dl> <Dd> tan ⁡ θ ≈ sin ⁡ θ = L 2 l = L 2 l ⇒ tan ⁡ θ 1 tan ⁡ θ 2 ≈ L 1 2 l L 2 2 l (\ displaystyle \ tan \ theta \ approx \ sin \ theta = (\ frac (\ frac (L) (2)) (l)) = (\ frac (L) (2l)) \ Rightarrow (\ frac (\ tan \ theta _ (1)) (\ tan \ theta _ (2))) \ approx (\ frac (\ frac (L_ (1)) (2l)) (\ frac (L_ (2)) (2l)))) </Dd> </Dl> </Td> <Td> <P> </P> <Table> <Tr> <Td> <P> </P> </Td> <Td> <P> </P> </Td> <Td> <P> </P> </Td> </Tr> <Tr> <Td> <P> </P> </Td> </Tr> </Table> </Td> <Td> <P> (7) </P> </Td> </Tr> </Table> <Tr> <Td> <P> </P> <Dl> <Dd> tan ⁡ θ ≈ sin ⁡ θ = L 2 l = L 2 l ⇒ tan ⁡ θ 1 tan ⁡ θ 2 ≈ L 1 2 l L 2 2 l (\ displaystyle \ tan \ theta \ approx \ sin \ theta = (\ frac (\ frac (L) (2)) (l)) = (\ frac (L) (2l)) \ Rightarrow (\ frac (\ tan \ theta _ (1)) (\ tan \ theta _ (2))) \ approx (\ frac (\ frac (L_ (1)) (2l)) (\ frac (L_ (2)) (2l)))) </Dd> </Dl> </Td> <Td> <P> </P> <Table> <Tr> <Td> <P> </P> </Td> <Td> <P> </P> </Td> <Td> <P> </P> </Td> </Tr> <Tr> <Td> <P> </P> </Td> </Tr> </Table> </Td> <Td> <P> (7) </P> </Td> </Tr> <Dl> <Dd> tan ⁡ θ ≈ sin ⁡ θ = L 2 l = L 2 l ⇒ tan ⁡ θ 1 tan ⁡ θ 2 ≈ L 1 2 l L 2 2 l (\ displaystyle \ tan \ theta \ approx \ sin \ theta = (\ frac (\ frac (L) (2)) (l)) = (\ frac (L) (2l)) \ Rightarrow (\ frac (\ tan \ theta _ (1)) (\ tan \ theta _ (2))) \ approx (\ frac (\ frac (L_ (1)) (2l)) (\ frac (L_ (2)) (2l)))) </Dd> </Dl>

What is the formula of coulomb's law